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Nutrition mineral intake method

Nutrition mineral intake method


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I always wonder if rather than getting minerals from food, can I directly eat them and will they have same effect as in food, e.g. can I eat iron filings for iron, magnesium and drink hard water for calcium?

Is there any difference between having minerals through food or directly eating metals?


To absorb essential elements, body must get them in form of stable ions. So for calcium and magnesium, our body absorbs them from the hard water in the same way it obtains from other sources and uses them identically. For iron, we cannot obtain iron from iron fillings because iron reacts with water and other chemicals in our body which can produce harmful effects. For further information on absorbtion of calcium from hard water visit http://goaskalice.columbia.edu/answered-questions/calcium-hard-water


Nutrition An Important Life Processes

Nutrition is one of the important part in life of living organisms. All living things perform various activities in their life and for performing this activities a living thing requires energy. The energy is obtained from food that a organisms eat.

Definitions

  1. Nutrition – Nutrition can be defined as Intake of food by any living organism and Utilization of that food is called Nutrition.
  2. Respiration – Respiration processes includes Breathing of oxygen as well as oxidation of food into cells to release energy.
  3. Transportation – Transport of different gases as well as digested food to different parts of a body.
  4. Excretion – Excretion is removal of undigested, waste material from the body is called as Excretion.

Nutrition word is derived from the word nutrient. Nutrient can be an organic or inorganic form of food. This is used for generation of energy to carry out various Physical and metabolic activities of living things. This process is important for survival of a living organism. Sources of food may be simple or complex. Glucose, Starch, Carbohydrate, Fats and Proteins, Vitamins are the different form of food used to derive energy.

In simple words Nutrient can be defined as the food consumed by living organism from the surrounding and utilize it as a source of energy . The energy obtained by the utilization of food is used for biosynthesis of the body components like cells, organs and tissues. The food taken by an organism is made up of nutrients like carbohydrates, fats , vitamins, minerals, protein and water. Thus we can define Nutrition as intake of food or we can say intake of nutrients and utilization of that nutrients by organism in form of energy.

1 ] Mode of Nutrition

Mode of nutrition in nothing but the method of obtaining of food by an organism. There are vast number of living things on earth and each and every species of life have a different method of obtaining or we can say intake of food. Depending on the method used for obtaining food the organism are divided into two main groups and that are

A] Autotrophic Mode of Nutrition

B] Heterotrophic Mode of Nutrition

A] Autotrophic Mode of Nutrition

Autotrophic mode of nutrition means nutrition carried out by own self. The organism synthesize its food by using the Carbon dioxide, Water and Sunlight as the source of energy.

Thus we can define it as” A mode of nutrition in which organism which synthesis its own food by used of carbon dioxide, water and sunlight as a source of energy” . The green plants show autotrophic mode of nutrition as they have chlorophyll pigment present in the cell. Some bacteria also show autotrophic mode of nutrition. The organisms which show autotrophic mode of nutrition are called as autotrophic organism or just autotrophs. This autotrophs make their food from inorganic substances present in the surrounding like carbon dioxide, water, soil and sunlight.

The chlorophyll pigment present in the cells of plants and this pigment is capable of trapping the sunlight energy.The processes of photosynthesis is used for making their own food by autotrophs. Photosynthesis is a processes in which the trapped carbon dioxide and inorganic substances like soil, water and carbon dioxide is used to prepare their own food.

B] Heterotrophic Mode of Nutrition

In heterotrophic mode of nutrition the nutrition is obtained from other sources.In this mode of nutrition the living things are unable to synthesize its own food they are depended on other life forms for their nutrition.In short we can say hetrotrophs are dependent on food that is made by autotrophs or consume autotrophs and other animals. Most of the organism are hetrotrophs like animals, bacteria, fungi and human beings.

We can define heterotrophs as ” The living things that are unable to synthesize their own food by using inorganic substances and are completely dependent on autotrophs and for their food and consume other animals are called as heterotrophs. Living things like bacteria, fungus, yeast, animals and human being are hetrotrophic in nature.

There are three types of Heterophic Nutrition

1. Saprotrophic nutrition – Saprotrophic mode of nutrition is a nutrition where living things obtain its food from dead plants and animals. The meaning of ‘sapro’ means rotten so a saprophytic is a organism depend on dead and rotten plants and animal. The dead and decaying matter is in complex form this saprophytes convert this complex form of nutrients to simple form outside their body and then consume the simple form of nutrients. Generally the fungus like yeast, molds, mushroom and some bacteria are included in this class of saprophytes.

2. Parasitic nutrition – Parasitic mode of nutrition is a mode of nutrition in which the organism obtain its food from the body of other living organism. The parasite is a organism that enter the body of a host organism and derive its food without killing it. Parasite cause a harm to host.The diseases caused in plants, animals and human being are due to parasites. Generally bacteria, fungi, and some plants show parasitic mode of nutrition

There are two types of parasites that are Ectoparasite and Endoparasite. Ectoparasite are the parasite that live on outer surface of host body that is skin surface of host. Endoparasite are the parasites that enter in the body of host and reach different organs of host.

3. Holozoic nutrition

Holozoic nutrition is a nutrition in which the living thing take a plant or animal product as food source. Generally most of the animals take the food in the body by processes of ingestion, further the complex food is taken and digested into simple molecules by process of digestion. The digested food is absorbed into to the cells of body by absorption. Lastly the undigested waste product are thrown out of body by process of egestion. Human beings and almost all animals show holozoic mode of nutrition.


34: Animal Nutrition and the Digestive System

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All living organisms need nutrients to survive. While plants can obtain the molecules required for cellular function through the process of photosynthesis, most animals obtain their nutrients by the consumption of other organisms. At the cellular level, the biological molecules necessary for animal function are amino acids, lipid molecules, nucleotides, and simple sugars. However, the food consumed consists of protein, fat, and complex carbohydrates. Animals must convert these macromolecules into the simple molecules required for maintaining cellular functions, such as assembling new molecules, cells, and tissues. The conversion of the food consumed to the nutrients required is a multi-step process involving digestion and absorption. During digestion, food particles are broken down to smaller components, and later, they are absorbed by the body.


Assessment of dietary intake and mineral status in pregnant women

Purpose: To evaluate the dietary intake of pregnant women and their nutritional status of Ca, Mg, Fe, Zn, and Cu, as the nutritional status of pregnant women is an important factor for the proper progression of a pregnancy and the development and health of the foetus.

Methods: The study was conducted on 108 pregnant women ages 18-42, at 6-32 weeks of gestation. We used a questionnaire and a 24-h recall nutrition interview. Hair samples were taken for testing and the level of each mineral was assessed using atomic absorption spectrometry. The results were analysed using the Dietetyk and Statistica 10 software.

Results: Low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid intake were seen in the pregnant women, with the use of dietary supplements significantly increasing their intake of Fe, Zn, and folic acid. The concentration of zinc and magnesium in the women's hair was shown to be affected by their age and, in the case of magnesium, by the week of pregnancy.

Conclusions: It was observed that the diet of pregnant women is characterised by low levels of Fe, Zn, Ca, Mg, vitamin D, and folic acid. Dietary supplementation with vitamins and minerals significantly increases the daily Fe and folic acid intake in pregnant women. The concentration of Zn and Mg in hair depends on the age of pregnant women and Mg level in the hair of women decreases during pregnancy.

Keywords: Dietary habits Folic acid Minerals Pregnancy Vitamin D.

Conflict of interest statement

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee, and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.


Plant Root Exudates𠅊 Source of Molecular Signals

Metabolic Signals to Recruit Favorable Microbes

The growth of soil microbes is usually carbon-limited, so the high amounts of sugars, amino acids, and organic acids that plants deposit into the rhizosphere represent a valuable nutrition source (Bais et al., 2006). However, deposition of this labile carbon does not necessarily foster the recruitment of favorable microbes, because pathogenic strains can also use these molecules as growth substrates. Therefore, it can be postulated that plants have evolved recognition mechanisms to discriminate beneficial microorganisms from those that need to be repelled. In such a case, the specific molecules present in root exudates that contribute to shaping the microbial community structure are potential targets for plant breeding strategies that seek to engineer the rhizosphere microbiome. It has been shown that plant root exudates contain components used in belowground chemical communication strategies, such as flavonoids, strigolactones, or terpenoids (Bais et al., 2006 Venturi and Fuqua, 2013 Massalha et al., 2017). Studies on the microbiome of different plant species and accessions revealed strong variations, leading to the hypothesis that exudates are crucial in shaping plant–microbe interactions (Hartmann et al., 2009). Furthermore, it has been shown that plants specifically attract beneficial interaction partners via root derived signals (Neal et al., 2012 Lareen et al., 2016).

Up to now, most information about signal perception and transduction in plant–microbe interactions comes from the field of plant pathology, where plant receptor-like kinases (RLKs) play a major role (Antolín-Llovera et al., 2012). In case of mutualistic interactions, nodulation and mycorrhizal interactions serve as model systems to identify recognition mechanisms between plants and microbes (Delaux et al., 2015 Lagunas et al., 2015). In parallel to recognizing the microbial interaction partner by the plant, also microbes have to recognize their mutual interaction partner (the plant root). It is widely accepted that root exudates contribute to the establishment of the root microbiome (Massalha et al., 2017). The term “root exudates” describes the molecules that are selectively secreted by roots and distinguishes it from the sloughing-off of root border cells (Walker et al., 2003). The overall release of fixed carbon compounds (border cells and exudates) into the surrounding soil is termed as rhizodeposition (Jones et al., 2004 Dennis et al., 2010). Data about the amount of rhizodeposition range between 5 and 30% of the total amount of fixed carbon (Bekku et al., 1997 Hütsch et al., 2002 Dennis et al., 2010), which generally means a large loss of reduced-C for biomass and represents a considerable impact on the carbon budget of individual plants and also entire ecosystems (Badri and Vivanco, 2009 Bardgett et al., 2014). In a 14 C approach, Hütsch et al. (2002) found remarkable differences in the amount of C-release among six different plant species ranging from 11.6 (wheat) to 27.7 (oil radish) mg C/g root dry matter. Also, the composition of these exudates varied between species, with oil radish exudates being rich in organic acids whereas pea exudates are rich in sugars. These data indicate that various plant species differentially modulate the chemical composition of their rhizospheres, which in turn might impact the associated microbial community. The recruitment of beneficial microbes might be crucial under environmental stress conditions such as nutrient limitation, pathogen attack, pests, high salt, or heavy metal stress.

Issues to Consider When Analyzing Root Exudates

To fully understand the dynamic interactions between soil microbes and plant roots, it is necessary to elucidate the specific molecules within root exudates that can recruit favorable microbial strains. This is a challenging problem in analytical biochemistry, because various biological and methodological issues must be addressed to undertake biologically insightful analyses of plant root exudates (Rovira, 1969). Regarding cultivation, artificial plant growth systems cannot mirror the natural conditions in soil, but on the other hand, it is difficult to unravel the relevant communication signals occurring in soil, due to chemical interaction of metabolites with the soil matrix, and background metabolites released from decomposing organic matter or microbial exudation. Most analyses therefore settle on hydroponic cultivation, sometimes with an inert material to scaffold the roots. When sampling, the experimenter must choose whether to collect exudates in simple deionized water, or a more realistic medium containing mineral salts. Furthermore, it is effectively impossible to design an experimental approach that can differentiate exudates from sloughed-off border cells. A comprehensive summary on exudate collection and influences (e.g., pH, re-uptake by roots, incubation period) is presented in Vranova et al. (2013). For data acquisition, researchers are increasingly using unbiased mass spectrometry (MS) approaches such as gas chromatography (GC)-MS and liquid chromatography (LC)-MS. However, detection of all metabolites in a sample is impossible due to physiochemical biases imposed by the selected extraction method, sample clean-up procedure, matrix effects and analytical technique (Weston et al., 2015). Therefore, different methods have to be combined for a comprehensive view on the metabolite profile. The subsequent analysis of the derived MS data is a huge challenge, beginning with data processing algorithms that enable feature detection, peak alignment and different normalization methods. These normalization and scaling algorithms have a large impact on the outcome of an analysis (Worley and Powers, 2013). To validate the identity of specific mass spectral features, fragmentation data (MS 2 or MS n ) are acquired and compared against publicly available databases (Afendi et al., 2013 Misra and van der Hooft, 2016), or authentic standards (if available). Taken together, these challenges mean that comprehensive analysis of root exudates is not trivial (Figure ​ Figure3 3 ).

Technical considerations for analyses of root exudates. Comprehensive analyses of root exudate composition are crucial to advance our knowledge of plant–microbe interactions, but experimenters must consider the technical challenges at each step of the analytical workflow. First the growth system must be carefully considered, particularly whether to use soil or hydroponics, which each have advantages and disadvantages. At sampling, those using hydroponic systems must decide whether to collect the exudates in nutrient solution or deionized water, whereas those using soil systems must consider how to separate exudates from the soil matrix. During sample preparation, there are a multitude of options for sample concentration and clean-up, which will influence sample composition. Clearly, the mass spectrometry methodology used for data acquisition will play a crucial role in the workflow, because different setups allow the detection of different molecules. Finally, there is a growing awareness that data processing and analysis strategies also play a key role in shaping the derived data.

Recent Approaches to Analyze Root Exudate Composition

Various studies have described analyses of plant root exudates, with Phillips et al. (2008) developing a method to collect exudates from mature trees in the field, although microbial metabolism probably makes a significant impact upon this non-sterile system. That said, microbial nutrient uptake is an interesting aspect of plant–microbe nutritional interactions, with a fast degradation of flavonoid glucosides being observed by Carlsen et al. (2012) when comparing the flavonoid content in two soils and after different legume cultivations. To avoid microbial impact upon root exudate profiles, researchers have established diverse approaches of axenic hydroponic cultivation systems (Badri et al., 2008 Oburger et al., 2013 Strehmel et al., 2014), which are easier to control, even though they represent artificial plant cultivation systems and plant responses might also include stress reactions due to oxygen limitation and insufficient root support. Furthermore, hydroponics is well suited for sampling of exudates, as the total liquid can directly been taken for further sample preparation procedures and root damage is minimized. However, collection of exudates widely ranges in timescale and the used collection medium (nutrient solution or water). Badri et al. (2008) collected root exudates from Arabidopsis thaliana in nutrient solution for 3 and 7 days for analysis by LC-MS and revealed that most compounds are present only after the longer incubation period. It could be hypothesized that this observation is due to sloughed-off border cells. Nevertheless, they also compared the exudate composition against root composition and stated an 80% difference based on detected molecular masses (Badri et al., 2008). Also Strehmel et al. (2014) applied a 7-day collection period in nutrient solution to obtain sufficient amounts of exudates from A. thaliana. In contrast, Carvalhais et al. (2010) applied only a 6-h exudate collection period to Zea mays plants to minimize the effect of sloughed-off border cells, but used deionized water as collection medium. A similar approach has been used for barley root exudates that were collected for 4 h in deionized water (Tsednee et al., 2012). For a short-term exudate collection period from Arabidopsis a high amount of plants has been required to obtain sufficient amounts of exudates for LC-MS analysis (Schmid et al., 2014). A direct comparison of different plant cultivation and exudate collection techniques revealed a huge impact on metabolite patterns (Oburger et al., 2013). Especially, long incubations in deionized water may lead to overestimated exudation rates due to the high transmembrane gradient of solutes in low ionic strength medium (Neumann and Römheld, 1999 Oburger et al., 2013). To date, most published data on exudates concentrate on specific metabolite classes such as primary metabolites (Neumann and Römheld, 1999 Dakora and Phillips, 2002 Rudrappa et al., 2008 Carvalhais et al., 2010 Tan et al., 2013 Warren, 2015 Kawasaki et al., 2016), hormones (Foo et al., 2013), flavonoids (Graham, 1991 Hughes et al., 1999 Weisskopf et al., 2006 Cesco et al., 2010), or phytosiderophores (Oburger et al., 2014). Non-targeted metabolite profiling approaches of root exudates have been applied less frequently, although Strehmel et al. (2014) provided a comprehensive overview on secondary metabolites in Arabidopsis root exudates using LC-MS. In follow-up experiments, the data collection was complemented by GC-MS data and extended by a comparison of 19 Arabidopsis accessions (Monchgesang et al., 2016), co-cultivation with Piriformospora indica (Strehmel et al., 2016) and data from phosphate limitation (Ziegler et al., 2016). As MS technology continues to improve, it can be expected that more studies will undertake untargeted analyses of root exudate profiles.

How Root Exudates Differ Across Plant Genotype and Nutrient Limitation

If root exudate profiles are to be a potential breeding target for increasing plant–microbe nutritional cooperation (Kuijken et al., 2015), then it must be first understood how exudate composition varies across genotypes or in response to nutrient deprivation. Recent studies have contributed to our knowledge of this phenomenon, with the effects of phosphate limitation investigated in Ziegler et al. (2016), and variation across accessions shown in Monchgesang et al. (2016) and also Micallef et al. (2009). Comparing exudate profiles across 19 natural Arabidopsis accessions showed a high natural variation for glycosylated and sulfated metabolites, such as flavonoids, glucosinolate degradation products, salicylic acid catabolites and polyamine derivatives (Monchgesang et al., 2016). Regarding root exudation changes induced by nutrient limitation, it seems that phosphate deficiency results in a higher abundance of oligolignols and a lower abundance of coumarins (Ziegler et al., 2016). Future experiments could investigate a different panel of plant genotypes, perhaps where previous experiments have defined a phenotypic difference that is potentially linked to root exudation profiles. One possibility involves comparing genotypes that have shown contrasting affinity to recruit favorable microbes (Haney et al., 2015), or genotypes that differ in their nutrient starvation responses (Ikram et al., 2012). Another option is root exudate profiling to analyze the phenotypic effects of mutants that were identified by GWAS studies (Wintermans et al., 2016).

Specific Molecules in Root Exudates Linked to Plant–Microbe Nutritional Interactions

From our current knowledge of root exudates, is it possible to pinpoint a set of molecules that are particularly promising for recruiting favorable microbes to the rhizosphere? In legumes, it is well described that the flavonoid pathway has a huge impact on attracting rhizobia bacteria to roots and inducing NOD gene expression (Eckardt, 2006 Maj et al., 2010 Abdel-Lateif et al., 2012 Weston and Mathesius, 2013). Flavonoids are also crucial for hyphal branching and thus promoting mycorrhizal interaction (Abdel-Lateif et al., 2012 Hassan and Mathesius, 2012). Both of these interactions result in increased plant nutrient uptake, with mycorrhiza and root nodules boosting phosphorus and nitrogen, respectively. Perhaps other plants and soil bacteria have also tapped into this signaling pathway, and further analysis of root exudates will give us clues as to whether flavonoids play a role in this communication leading to increased nutrient uptake. From analyzing plant mutants, candidate genes that have been investigated so far are related to the transfer of metabolites into the rhizosphere (Badri et al., 2008), hormonal signaling (Foo et al., 2013 Carvalhais et al., 2015), or to biosynthesis, e.g., genes from phenylpropanoid pathway (Wasson et al., 2006 Zhang et al., 2009). These results give us some hints about candidate molecules that are exuded by plant roots to recruit beneficial bacteria, such as strigolactones and flavonols, and presumably further analyses will expand this list. To fully exploit this knowledge, then it is desirable to identify which microbial strains are recruited by these molecules, and what benefits they confer to the plant.


Vitamins

The name “vitamin” comes from Casimir Funk, who in 1912 thought “vital amines” (similar to amino acids) were responsible for preventing what we know now as vitamin deficiencies. He coined the term “vitamines” to describe these organic substances that were recognized as essential for life, yet unlike other organic nutrients (carbohydrates, protein, and fat), do not provide energy to the body. Eventually, when scientists discovered that these compounds were not amines, the ‘e’ was dropped to form the term “vitamins.” 1

Classification of Vitamins

Vitamins are essential, non-caloric, organic micronutrients. There is energy contained in the chemical bonds of vitamin molecules, but our bodies don’t make the enzymes to break these bonds and release their energy instead, vitamins serve other essential functions in the body. Vitamins are traditionally categorized into two groups: water-soluble or fat-soluble. Whether vitamins are water-soluble or fat-soluble can affect their functions and sites of action. For example, water-soluble vitamins often act in the cytosol of cells (the fluid inside of cells) or in extracellular fluids such as blood, while fat-soluble vitamins play roles such as protecting cell membranes from free radical damage or acting within the cell’s nucleus to influence gene expression.

Figure 8.1. Classification of vitamins as water-soluble or fat-soluble.

One major difference between water-soluble and fat-soluble vitamins is the way they are absorbed in the body. Water-soluble vitamins are absorbed directly from the small intestine into the bloodstream. Fat-soluble vitamins are first incorporated into chylomicrons, along with fatty acids, and transported through the lymphatic system to the bloodstream and then on to the liver. The bioavailability (i.e., the amount that gets absorbed) of these vitamins is dependent on the food composition of the diet. Because fat-soluble vitamins are absorbed along with dietary fat, if a meal is very low in fat, the absorption of the fat-soluble vitamins in that meal may be impaired.

Figure 8.2. “Absorption of Fat-Soluble and Water-Soluble Vitamins.”

Fat-soluble and water-soluble vitamins also differ in how they are stored in the body. The fat-soluble vitamins—vitamins A, D, E, and K—can be stored in the liver and the fatty tissues of the body. The ability to store these vitamins allows the body to draw on these stores when dietary intake is low, so deficiencies of fat-soluble vitamins may take months to develop as the body stores become depleted. On the flip side, the body’s storage capacity for fat-soluble vitamins increases the risk for toxicity. While toxic levels are typically only achieved through vitamin supplements, if large quantities of fat-soluble vitamins are consumed, either through foods or supplements, vitamin levels can build up in the liver and fatty tissues, leading to symptoms of toxicity.

There is limited storage capacity in the body for water-soluble vitamins, thus making it important to consume these vitamins on a daily basis. Deficiency of water-soluble vitamins is more common than fat-soluble vitamin deficiency because of this lack of storage. That also means toxicity of water-soluble vitamins is rare. Because of their solubility in water, intake of these vitamins in amounts above what is needed by the body can, to some extent, be excreted in the urine, leading to a lower risk of toxicity. Similar to fat-soluble vitamins, a toxic intake of water-soluble vitamins is not common through food sources, but is most frequently seen due to supplement use.

Characteristics of Fat-Soluble Vitamins

Characteristics of Water-Soluble Vitamins

Protect cell membranes from free radical damage act within the cell’s nucleus to influence gene expression

Act in the cytosol of cells or in extracellular fluids such as blood

Absorbed into lymph with fats from foods

Absorbed directly into blood

Large storage capacity in fatty tissues

Little to no storage capacity

Do not need to be consumed daily to prevent deficiency (may take months to develop)

Need to be consumed regularly to prevent deficiency

Table 8.1. Characteristics of fat-soluble and water-soluble vitamins.


Nutrition in Animals

Nutrition is a factor that is important for all living beings. For animals and plants also, it is important for their survival. Through the process of photosynthesis, plants prepare their own food but animals cannot prepare their food and therefore are dependent on plants or other animals for their food.

Animals fulfill their nutritional needs either by eating plants directly (herbivores) or indirectly by eating animals that have consumed plants (carnivores). Animals that depend on both plants and animals are termed as omnivores. For proper growth and survival, all the organisms require food irrespective of the source they derive from their food.

Food has different components, called nutrients, like carbohydrates, fats, minerals, proteins, and vitamins, which are required for the maintenance of the body. These components are complex and cannot be used directly, so they are broken down into simpler components by the process of digestion.

Feeding Habits of Animals

Feeding habits of animals provide them their adequate nutrition which they intake by the process called Ingestion. The method of ingestion differs in different animals. For example- Nectar is the source of food for bees and hummingbirds, python tends to swallow its prey, and the grass is being ingested by cattle.

Different feeding habits of animals lead to an Evolution. The earliest forms were large amphibians that ate fish among the terrestrial animals. While amphibians like frogs fed on small fish and insects, the reptiles began feeding on other animals and plants.

Evolution of form and function is caused by the specialization of organisms towards specific food sources and of course specific ways of eating.

For instance, the difference in mouthparts and teeth in whales, mosquitos, tigers, and sharks or distinct forms of beaks in birds, such as in hawks, woodpeckers, pelicans, hummingbirds, and parrots are a perfect example of adaptation to different types of eating by these animals.

Animals can be divided into the following groups depending upon their food habits:

Herbivores: Animals that depend upon plants and fruits for their nutrition are called Herbivores. Cows, goats, sheep, buffaloes, etc. are herbivores.

Carnivores: Carnivores are animals that depend upon other animals for food. Lion, tigers, wolfs are some of the carnivores.

Omnivores: These include organisms that eat both plants and animals. Humans, bear, dogs, crow are omnivores.

Types of Nutrition in Animals

The different types of nutrition in animals include:

Filter Feeding: It is a process of acquiring nutrients from particles suspended in water. This method is commonly used by fish.

Deposit feeding: It is the process of obtaining nutrients from particles suspended in the soil. Earthworms use this method to take nutrition.

Fluid feeding: When one animal obtains nutrients by consuming other organisms’ fluids. Honey bees, mosquitos follow this mode of food intake.

Bulk feeding: Eating whole organisms and grabbing nutrients from it.

Ram feeding and suction feeding: Consuming prey as food via the fluids around it. This mode of ingestion is usually adopted by aquatic animals such as bony fish.

Process of Nutrition in Animals

The process of nutrition in animals are as follows -

Ingestion is the process of taking in food.

In this process, the larger food particles are broken down into smaller, water-soluble particles. There are physical or chemical for digesting food.

The digested food is absorbed in the bloodstream through the intestinal wall.

The absorbed food is used for energy, growth and repair of the cells of the body.

The undigested food is removed out of the body in the faeces. This process is known as egestion.


Utilization of food by the body

The human body can be thought of as an engine that releases the energy present in the foods that it digests. This energy is utilized partly for the mechanical work performed by the muscles and in the secretory processes and partly for the work necessary to maintain the body’s structure and functions. The performance of work is associated with the production of heat heat loss is controlled so as to keep body temperature within a narrow range. Unlike other engines, however, the human body is continually breaking down ( catabolizing) and building up ( anabolizing) its component parts. Foods supply nutrients essential to the manufacture of the new material and provide energy needed for the chemical reactions involved.

Carbohydrate, fat, and protein are, to a large extent, interchangeable as sources of energy. Typically, the energy provided by food is measured in kilocalories, or Calories. One kilocalorie is equal to 1,000 gram-calories (or small calories), a measure of heat energy. However, in common parlance, kilocalories are referred to as “calories.” In other words, a 2,000-calorie diet actually has 2,000 kilocalories of potential energy. One kilocalorie is the amount of heat energy required to raise one kilogram of water from 14.5 to 15.5 °C at one atmosphere of pressure. Another unit of energy widely used is the joule, which measures energy in terms of mechanical work. One joule is the energy expended when one kilogram is moved a distance of one metre by a force of one newton. The relatively higher levels of energy in human nutrition are more likely to be measured in kilojoules (1 kilojoule = 10 3 joules) or megajoules (1 megajoule = 10 6 joules). One kilocalorie is equivalent to 4.184 kilojoules.

The energy present in food can be determined directly by measuring the output of heat when the food is burned (oxidized) in a bomb calorimeter. However, the human body is not as efficient as a calorimeter, and some potential energy is lost during digestion and metabolism. Corrected physiological values for the heats of combustion of the three energy-yielding nutrients, rounded to whole numbers, are as follows: carbohydrate, 4 kilocalories (17 kilojoules) per gram protein, 4 kilocalories (17 kilojoules) per gram and fat, 9 kilocalories (38 kilojoules) per gram. Beverage alcohol ( ethyl alcohol) also yields energy—7 kilocalories (29 kilojoules) per gram—although it is not essential in the diet. Vitamins, minerals, water, and other food constituents have no energy value, although many of them participate in energy-releasing processes in the body.

The energy provided by a well-digested food can be estimated if the gram amounts of energy-yielding substances (non-fibre carbohydrate, fat, protein, and alcohol) in that food are known. For example, a slice of white bread containing 12 grams of carbohydrate, 2 grams of protein, and 1 gram of fat supplies 67 kilocalories (280 kilojoules) of energy. Food composition tables (see table) and food labels provide useful data for evaluating energy and nutrient intake of an individual diet. Most foods provide a mixture of energy-supplying nutrients, along with vitamins, minerals, water, and other substances. Two notable exceptions are table sugar and vegetable oil, which are virtually pure carbohydrate (sucrose) and fat, respectively.

The energy value and nutrient content of some common foods
food energy (kcal) carbohydrate (g) protein (g) fat(g) water (g)
Source: Jean A.T. Pennington, Bowes and Church's Food Values of Portions Commonly Used, 17th ed. (1998).
whole wheat bread (1 slice, 28 g) 69 12.9 2.7 1.2 10.6
white bread (1 slice, 25 g) 67 12.4 2.0 0.9 9.2
white rice, short-grain, enriched, cooked (1 cup, 186 g) 242 53.4 4.4 0.4 127.5
lowfat milk (2%) (8 fl oz, 244 g) 121 11.7 8.1 4.7 17.7
butter (1 tsp, 5 g) 36 0 0 4.1 0.8
cheddar cheese (1 oz, 28 g) 114 0.4 7.1 9.4 10.4
lean ground beef, broiled, medium (3.5 oz, 100 g) 272 0 24.7 18.5 55.7
tuna, light, canned in oil, drained (3 oz, 85 g) 168 0 24.8 7.0 50.9
potato, boiled, without skin (1 medium, 135 g) 117 27.2 2.5 0.1 103.9
green peas, frozen, boiled (1/2 cup, 80 g) 62 11.4 4.1 0.2 63.6
cabbage, red, raw (1/2 cup shredded, 35 g) 9 2.1 0.5 0.1 32.0
orange, navel, raw (1 fruit, 131 g) 60 15.2 1.3 0.1 113.7
apple, raw, with skin (1 medium, 138 g) 81 21.0 0.3 0.5 115.8
white sugar, granulated (1 tsp, 4 g) 15 4.0 0 0 0

Throughout most of the world, protein supplies between 8 and 16 percent of the energy in the diet, although there are wide variations in the proportions of fat and carbohydrate in different populations. In more prosperous communities about 12 to 15 percent of energy is typically derived from protein, 30 to 40 percent from fat, and 50 to 60 percent from carbohydrate. On the other hand, in many poorer agricultural societies, where cereals comprise the bulk of the diet, carbohydrate provides an even larger percentage of energy, with protein and fat providing less. The human body is remarkably adaptable and can survive, and even thrive, on widely divergent diets. However, different dietary patterns are associated with particular health consequences (see nutritional disease).


Animal Nutrition

Meeting livestock nutritional requirements is extremely important in maintaining acceptable performance of neonatal, growing, finishing and breeding animals. From a practical standpoint, an optimal nutritional program should ensure adequate intakes of amino acids (both traditionally classified essential and nonessential), carbohydrates, fatty acids, minerals, and vitamins by animals through a supplementation program that corrects deficiencies in basal diets (e.g., corn- and soybean meal-based diets for swine milk replacers for calves and lambs and available forage for ruminants).

Benefits of dietary supplements

Additionally, dietary supplementation with certain nutrients (e.g., arginine, glutamine, zinc, and conjugated linoleic acid) can regulate gene expression and key metabolic pathways to improve fertility, pregnancy outcome, immune function, neonatal survival and growth, feed efficiency, and meat quality. Overall, the proper balance of protein, energy, vitamins and all nutritionally important minerals in diets is needed to make a successful nutrition program that is both productive and economical. Both fundamental and applied research are required to meet this goal.

Reaching adequate water intake

Also crucial to the nutrition program for animals is water. Livestock may have health problems resulting from substandard quality water. Consuming water is more important than consuming food. A successful livestock enterprise requires a good water supply, in terms both of quantity and quality. Safe supplies of water are absolutely essential for livestock. If livestock do not drink enough safe water every day, intake of feed (roughages and concentrates) will drop, production will fall and the livestock producer will lose money.


Nutrition mineral intake method - Biology

Dietary patterns have varied over time depending on the agricultural practices and the climatic, ecologic, cultural, and socio-economic factors, which determine available foods. At present, virtually all dietary patterns adequately satisfy or even exceed the nutritional needs of population groups. This is true except where socio-economic conditions limit the capacity to produce and purchase food or aberrant cultural practices restrict the choice of foods. It is thought that if people have access to a sufficient quantity and variety of foods, they will meet their nutritional needs. The current practice of evaluating nutritive value of diets should include not only energy and protein adequacy but also the micronutrient density of the diet.

A healthy diet can be attained in more than one way because of the variety of foods, which can be combined. It is thus difficult to define the ranges of intake for a specific food, which should be included in a given combination to comply with nutritional adequacy. In practice, the set of food combinations which is compatible with nutritional adequacy is restricted by the level of food production sustainable in a given ecologic and population setting. In addition, there are economic constraints, which limit food supply at household level. The development of food-based dietary guidelines (FBDGs) by the FAO and WHO ( 1 ) recognises this and focuses on the combination of foods that can meet nutrient requirements rather than on how each specific nutrient is provided in adequate amounts.

The first step in the process of setting dietary guidelines is defining the significant diet-related public health problems in a community. Once these are defined, the adequacy of the diet is evaluated by comparing the information available on dietary intake with recommended nutrient intakes (RNIs). Nutrient intake goals under this situation are specific for a given ecologic setting, and their purpose is to promote overall health, control specific nutritional diseases (whether they are induced by an excess or deficiency of nutrient intake), and reduce the risk of diet-related multi-factorial diseases. Dietary guidelines represent the practical way to reach the nutritional goals for a given population. They take into account the customary dietary pattern and indicate what aspects should be modified. They consider the ecologic setting, socio-economic and cultural factors, and biologic and physical environment in which the population lives.

The alternative approach to defining nutritional adequacy of diets is based on the biochemical and physiologic basis of human nutritional requirements in health and disease. The quantitative definition of nutrient needs and its expression as RNIs have been important instruments of food and nutrition policy in many countries and have focused the attention of international bodies. This nutrient-based approach has served many purposes but has not always fostered the establishment of nutritional and dietary priorities consistent with the broad public health priorities at the national and international levels. It has permitted a more precise definition of requirements for essential nutrients when establishing RNIs but unfortunately has often been narrowly focused, concentrating on the precise nutrient requirement amount and not on solving the nutritional problems of the world. In contrast to RNIs, FBDGs are based on the fact that people eat food, not nutrients. As illustrated in this chapter, the notion of nutrient density is helpful for defining FBDGs and evaluating the adequacy of diets. In addition, they serve to educate the public through the mass media and provide a practical guide to selecting foods by defining dietary adequacy (1).

Advice for a healthy diet should provide both a quantitative and qualitative description of the diet for it to be understood by individuals, who should be given information on both size and number of servings per day. The quantitative aspects include the estimation of the amount of nutrients in foods and their bio-availability in the form they are actually consumed. Unfortunately, available food composition data for most foods currently consumed in the world are incomplete, outdated, or insufficient for evaluating true bio-availability. The qualitative aspects relate to the biologic utilisation of nutrients in the food as consumed by humans and explore the potential for interaction among nutrients. Such an interaction may enhance or inhibit the bio-availability of a nutrient from a given food source.

Including foods in the diet, which have high micronutrient density - such as pulses or legumes, vegetables (including green leafy vegetables), and fruits - is the preferred way of ensuring optimal nutrition including micronutrient adequacy for most population groups. Most population groups afflicted by micronutrient deficiency largely subsist on refined cereal grain or tuber-based diets, which provide energy and protein (with improper amino acid balance) but are insufficient in critical micronutrients. Figures 2-5 and Tables 1-4 included at the end of this chapter illustrate how addition of a variety of foods to the basic four diets (white rice- Figure 2 , corn tortilla- Figure 3 , refined couscous- Figure 4 , and potato- Figure 5 ) can increase the nutrient density of a cereal or tuber-based diet. There is a need for broadening the food base and diversification of diets. Much can be gained from adding reasonable amounts of these foods, which will add micronutrient density to the staple diet ( Table 1, 2, 3 and 4 ).

The recent interest in the role of phyto-chemicals and antioxidants on health and their presence in plant foods lend further support to the recommendation for increasing vegetables and fruit consumed in the diet. The need for dietary diversification is supported by the knowledge of the interrelationships of food components, which may enhance the nutritional value of foods and prevent undesirable imbalances, which may limit the utilisation of some nutrients. For example, fruits rich in ascorbic acid will enhance the absorption of ionic iron.

If energy intake is low (<8.368 MJ/day), for example, in the case of young children, sedentary women, or the elderly, the diet may not provide vitamin and mineral intakes sufficient to meet the RNIs. This situation may be of special relevance to the elderly, who are inactive, have decreased lean body mass, and typically decrease their energy intake. Young children, pregnant women, and lactating women, who have greater micronutrient needs relative to their energy needs, will also require increased micronutrient density.

The household is the basic unit for food consumption under most settings, and if there is sufficient food, individual members of the household can consume a diet with the recommended nutrient densities and meet their specific RNIs. However, appropriate food distribution within the family must be considered to ensure that children and women receive adequate food with high micronutrient density. Household food distribution must be considered when establishing general dietary guidelines and addressing the needs of vulnerable groups in the community. In addition, education detailing the appropriate storage and processing of foods to prevent micronutrient losses at the household level is important.

Dietary diversification when consuming cereal and tuber-based diets (rice, corn, wheat, potato, and cassava)

Dietary diversification is important to improve the intake of critical nutrients. The micronutrients selected discussed here, although limited in number, are of public health relevance or serve as markers for overall micronutrient intake. The chapters on individual nutrients will provide further details on food-related considerations for micronutrient adequacy. The nutrients selected for discussion below include some of the nutrients, which are most difficult to obtain in cereal and tuber-based diets. Nutrient deficiencies of vitamin A, iron, and zinc are widespread.

The vitamin A content of most staple diets can be significantly improved with the addition of a relatively small portion of plant foods rich in carotenoids, the precursors of vitamin A. For example, a usual portion of cooked carrots (50 g) added to a daily diet, or 21 g of carrots per 4.184 MJ, provides 500 mg retinol equivalents, which is the recommended nutrient density for this vitamin. The biologic activity of pro-vitamin A varies among different plant sources, and fruits and vegetables such as carrots, mango, papaya, and melon contain large amounts of nutritionally active carotenoids, ( 2, 3 ). Green leafy vegetables such as ivy gourd have been successfully used in Thailand as a source of vitamin A, and carotenoid-rich red palm oil serves as an easily available and excellent source of vitamin A in other countries. Consequently, a regular portion of these foods included in an individual’s diet may provide 100 percent or more of the daily requirement for retinol equivalents. Vitamin A is also present in animal food sources in a highly bio-available form. Therefore it is important to consider the possibility of meeting vitamin A needs by including animal foods in the diet. For example, providing minor amounts of fish or chicken liver (20-25 g) in the diet provides more than the recommended vitamin A nutrient density for virtually all age and sex groups.

A real gain in vitamin C intake can be achieved by including citrus fruit or other foods rich in ascorbic acid in the diet. For example, an orange or a small amount of other vitamin C-rich fruit (60 g of edible portion) provides the recommended ascorbic acid density. Adding an orange to a potato-based diet increases the level of vitamin C threefold. Other good vitamin C food sources are guava, amla, kiwi, cranberries, strawberries, papaya, mango, melon, cantaloupe, spinach, Swiss chard, tomato, asparagus, and Brussels sprouts. All these foods, when added to a diet or meal in regular portion sizes, will significantly improve the vitamin C density. Because ascorbic acid is heat labile, minimal cooking (steaming or stir-frying) is recommended to maximise the bio-available nutrient. The significance of consuming vitamin C with meals will be discussed relative to iron absorption (see Chapter 13 ).

Folate is now considered significant not only for the prevention of macrocytic anaemia, but also for normal foetal development. Recently, this vitamin was implicated in the maintenance of cardiovascular health and cognitive function in the elderly. Staple diets consisting largely of cereal grains and tubers are very low in folate but can be improved by the addition of legumes or green leafy vegetables. For example, a regular portion of cooked lentils (95 g) added to a rice-based diet can provide an amount of folate sufficient to meet the desirable nutrient density for this vitamin. Other legumes such as beans and peas are also good sources of this vitamin, but larger portions are needed for folate sufficiency (100 g beans and 170 g peas). Cluster bean and colacasia leaves are excellent folate sources used in the Indian diet. Another good source of folate is chicken liver only one portion (20-25 g) is sufficient to meet the desirable nutrient density for folate and vitamin A simultaneously. The best sources of folate are organ meats, green leafy vegetables, and sprouts. However, 50 percent or more of food folate is destroyed during cooking. Prolonged heating in large volumes of water should be avoided, and it is advisable to consume the water used in the cooking of vegetables.

Minerals such as iron and zinc are low in cereal and tuber-based diets, but the addition of legumes can slightly improve the iron content of those diets. However, the bio-availability of this non-heme iron source is low. Therefore, it is not possible to meet the recommended levels of iron and zinc in the staple-based diets through a food-based approach unless some meat, poultry, or fish is included. For example adding a small portion (50 g) of meat, poultry, or fish will increase the total iron content as well as the amount of bio-available iron. For zinc the presence of a small portion (50 g) of meat, poultry, or fish will secure dietary sufficiency of most staple diets.

The consumption of ascorbic acid along with the food rich in iron will enhance absorption. There is a critical balance between enhancers and inhibitors of iron absorption. Nutritional status can be improved significantly by educating households on food preparation practices, which minimise the consumption of inhibitors of iron absorption for example, the fermentation of phytate-containing grains before the baking of breads to enhance iron absorption.

How to accomplish dietary diversity in practice

It is essential to work on strategies, which promote and facilitate dietary diversification to achieve complementarity of cereal or tuber-based diets with foods rich in micronutrients in populations with limited economics or limited access to food. A recent FAO and International Life Sciences Institute ( 4 ) publication proposed strategies to promote dietary diversification within the implementation of food-based approaches. These strategies, which follow, have been adapted or modified based on the discussions held in this consultation:

1. Community or home vegetable and fruit gardens . These projects should lead to increased production and consumption of micronutrient-rich foods (legumes, green leafy vegetables, and fruits) at the household level. The success of such projects requires a good knowledge and understanding of local conditions as well as the involvement of women and the community in general. These are key elements for supporting, achieving, and sustaining beneficial nutritional change at the household level. Land availability and water supply may present common constraints, which require local government intervention or support before they are overcome. The educational effort should be directed towards securing appropriate within-family distribution, which considers the needs of the most vulnerable members of the family, especially infants and young children. Separate FBDGs for vulnerable groups, such as pregnant and lactating women, children, and the elderly, should be developed.

2. Production of fish, poultry, and small animals (rabbits, goats, and guinea pigs). These are excellent sources of highly bio-available essential micronutrients such as vitamin A, iron, and zinc. The production of animal foods at the local level may permit communities to access foods which otherwise are not available because of their high costs. These types of projects also need some support from local governments or non-governmental organizations to overcome cost constraints of programme implementation, including the training of producers.

3. Implementation of large-scale commercial vegetable and fruit production . The objective of this initiative is to provide micronutrient-rich foods at reasonable prices through effective and competitive markets, which lower consumer prices without reducing producer prices. This will serve predominantly the urban and non-food-producing rural areas.

4. Reduction of post-harvest losses of the nutritional value of micronutrient-rich foods, such as fruits and vegetables . Improvement of storage and food-preservation facilities significantly reduces post-harvest losses. At the household level, the promotion of effective cooking methods and practical ways of preserving foods (solar drying of seasonal micronutrient-rich foods such as papaya, grapes, mangoes, peaches, tomatoes, and apricots) may significantly increase the access to bio-available micronutrient-rich foods. At the commercial level, grading, packing, transport, and marketing practices reduce losses, stimulate economic growth, and optimise income generation.

5. Improvement of micronutrient levels in soils and plants, which will improve the composition of plant foods and enhance yields . Current agricultural practices can improve the micronutrient content of foods through correcting soil quality and pH and increasing soil mineral content depleted by erosion and poor soil conservation. Long-term food-based solutions to micronutrient deficiencies will require improvement of agricultural practices, seed quality, and plant breeding (by means of a classical selection process or genetic modification).

The green revolution made important contributions to cereal supplies, and it is time to address the need for improvements in the production of legumes, vegetables, fruits, and other micronutrient-rich foods. FBDGs can serve to reemphasise the need for these crops.

It is well recognised that the strategies proposed to promote dietary diversity need a strong community-level commitment. For example, the increase in price of legumes associated with decreased production and lower demand needs to be corrected. The support of local authorities and government may facilitate the implementation of such projects because these actions require economic resources, which sometimes are beyond the reach of the most needy.

Practices which will enhance the success of food-based approaches

To achieve dietary adequacy of vitamin A, vitamin C, folate, iron, and zinc by using food-based approaches, food preparation and dietary practices must be considered. For example, it is important to recommend that vegetables rich in vitamin C, folate, and other water-soluble or heat-labile vitamins be minimally cooked in small amounts of water. For iron bio-availability it is essential to reduce the intake of inhibitors of iron absorption and to increase the intake of enhancers of absorption in a given meal. Following this strategy, it is recommended to increase the intake of: germinated seeds, fermented cereals, heat-processed cereals, meats, and fruits and vegetables rich in vitamin C and to encourage the consumption of tea, coffee, chocolate, or herbal teas at times other than with meals (see Chapter 13 and Chapter 16 ). Consumption of flesh foods improves zinc absorption whereas it is inhibited by consumption of diets high in phytate, such as diets based on unrefined cereal. Zinc availability can be estimated according to the phytate-to-zinc (molar) ratio of the meal ( 5 ).

This advice is particularly important for people who consume cereal and tuber-based diets. These foods constitute the main staples for most populations of the world, populations that are also most at risk for micronutrient deficiencies. Other alternatives - fortification and supplementation - have been proposed as stopgap measures when food-based approaches are not feasible or are still in progress. There is a definite role for fortification in meeting iron, folate, iodine, and zinc needs. Fortification and supplementation should be seen as complementary to food-based strategies and not as a replacement. Combined, all these strategies can go a long way toward stabilising the micronutrient status of populations at risk. Food-based approaches usually take longer to implement but once established are truly sustainable.

Delineating the role of supplementation and food fortification for nutrients which cannot be supplied by regular foods

Under ideal conditions of food access and availability, food diversity should satisfy micronutrient and energy needs of the general population. Unfortunately, for many people in the world, the access to a variety of micronutrient-rich foods is not possible. As demonstrated in our analysis of cereal and tuber-based diets ( see appendixes ), micronutrient-rich foods including small amount of flesh foods and a variety of plant foods (vegetables and fruits) are needed daily. This may not be realistic at present for many communities living under conditions of poverty. Food fortification and food supplementation are important alternatives that complement food-based approaches to satisfy the nutritional needs of people in developing and developed countries.

Fortification refers to the addition of nutrients to a commonly eaten food (the vehicle). It is possible for a single nutrient or group of micronutrients (the fortificant) to be added to the vehicle, which has been identified through a process in which all stakeholders have participated. This strategy is accepted as sustainable under most conditions and often is cost effective on a large scale when successfully implemented. Iron fortification of wheat flour and iodine fortification of salt is examples of fortification strategies with excellent results ( 6 ).

There are at least three essential conditions that must be met in any fortification programme( 6, 7 ): the fortificant should be effective, bio-available, acceptable, and affordable the selected food vehicle should be easily accessible and a specified amount of it should be regularly consumed in the local diet and detailed production instructions and monitoring procedures should be in place and enforced by law.

Food fortification with iron is recommended when dietary iron is insufficient or the dietary iron is of poor bio-availability, which is the reality for most people in the developing world and for vulnerable population groups in the developed world. Moreover, the prevalence of iron deficiency and anaemia in vegetarians and in populations of the developing world which rely on cereal or tuber foods is significantly higher than in omnivore populations.

Iron is present in foods in two forms, as heme iron, which is derived from flesh foods (meats, poultry, and fish), and as non-heme iron, which is the inorganic form present in plant foods such as legumes, grains, nuts, and vegetables ( 8, 9 ). Heme iron is highly (20-30 percent) absorbed and its bio-availability is relatively unaffected by dietary factors. Non-heme iron has a lower rate of absorption (2-10 percent), depending on the balance between iron absorption inhibitors (phytates, polyphenols, calcium, and phosphate) and iron absorption enhancers (ascorbic and citric acids, cysteine-containing peptides, ethanol, and fermentation products) present in the diet ( 8, 9 ) . Because staple foods around the world provide predominantly non-heme iron sources of low bio-availability, the traditionally eaten staple foods represent an excellent vehicle for iron fortification. Examples of foods, which have been fortified, are wheat flour, corn (maize) flour, rice, salt, sugar, cookies, curry powder, fish sauce, and soy sauce ( 8 ). Nevertheless the beneficial effects of consumption of iron absorption enhancers have been extensively proven and should always be promoted (i.e., consumption of vitamin C-rich food together with the non-heme iron source).

Iodine is sparsely distributed in the Earth’s surface and foods grown in soils with little or no iodine lack an adequate amount of this micronutrient. This situation had made iodine deficiency disorders exceedingly common in most of the world and highly prevalent in many countries before the introduction of salt iodisation ( 10 ). Only foods of marine origin are naturally rich sources of iodine. Salt is a common food used by most people worldwide, and the establishment of an well-implemented permanent salt-iodisation programme has been proven to eradicate iodine deficiency disorders (see Chapter 12 ). Universal salt iodisation is the best way to virtually eliminate iodine deficiency disorders by the year 2000 ( 4 ).

However, salt iodisation is not simply a matter of legislating mandatory iodisation of salt. It is important to determine the best fortification technique, co-ordinate the implementation at all salt production sites, establish effective monitoring and quality control programmes, and measure iodine fortification level periodically. The difficulties in implementing salt iodisation programmes arise primarily when the salt industry is widely dispersed among many small producers. The level of iodine fortification usually lies between 25 and 50 mg/kg salt. The actual amount should be specified according to the level of salt intake and magnitude of deficit at the country level, because iodine must be added within safe and effective ranges. Additionally, it is very important to implement a monitoring plan to control the amount of iodine in the salt at the consumer’s table, ( 10, 11 ). United Nations agencies responsible for assisting governments in establishing iodisation programmes should provide technical support for programme implementation, monitoring, and evaluation to ensure sustainability.

The body depends on a regular zinc supply provided by the daily diet because stores are quite limited. Food diversity analysis demonstrates that it is virtually impossible to achieve zinc adequacy in the absence of a flesh food source. Among flesh foods, beef is the best source of zinc and is followed by poultry and then fish. Zinc fortification programmes are being studied, especially for populations, which consume predominately plant foods. Fortification of cereal staple foods is a potentially attractive intervention, which could benefit the whole population as well as target the vulnerable population groups of children and pregnant women. Such addition of zinc to the diet would perhaps decrease the prevalence of stunting in many developing countries with low-zinc diets, because linear growth is affected by zinc supply.

The recommended nutrient density by the developers of the FAO/WHO ( 1 ) FBDGs for folic acid is 200 mg/4.184 MJ. Although this reference value is higher than other standards of reference, the increase in folic acid consumption by women of childbearing age is very important: it may improve birth weight and reduce the prevalence of neural tube defects by 50 percent. Elevated plasma homo-cysteine levels are considered to be an independent risk factor for heart disease a higher intake of folic acid may also benefit the rest of the population because it may lower homo-cysteine levels in adults (see Chapter 4 ). In addition, folate may improve the mental condition of the elderly population ( 12, 13 ).

Although the desirable folic acid density may be achieved through dietary diversity, it requires the daily presence of organ meats, green leafy vegetables, pulses, legumes, or nuts in the diet ( 14 ). Most population groups may not easily reach the appropriate level of folic acid consumption therefore, folic acid fortification has been recommended. The United States initiated mandatory folic acid fortification of cereal-grain products in January 1998. The fortification level approved in the United States is 140 mg/100 g product, which will increase the average woman’s intake by only 100 mg/day. This amount is considered safe (a dose, which will not mask pernicious anaemia, which results from vitamin B12 deficiency,) but it may be ineffective in lowering the occurrence of neural tube defects ( 15 ).

Supplementation refers to periodic administration of pharmacologic preparations of nutrients as capsules or tablets or by injection when substantial or immediate benefits are necessary for the group at risk. As established at the International Conference on Nutrition ( 16 ), nutritional supplementation should be restricted to vulnerable groups, which cannot meet their nutrient needs through food (women of childbearing age, infants and young children, elderly people, low socio-economic groups, displaced people, refugees, and populations experiencing other emergency situations). For example, iron supplementation is recognised as the only option to control or prevent iron deficiency anaemia in pregnant women. Supplementation with folic acid should be considered for women of childbearing age who have had a child with neural tube defect to prevent recurrence.

Food-based dietary guidelines

Food-based dietary guidelines (FBDGs) are an instrument of and expression of food and nutrition policy and should be based directly on diet and disease relationships of particular relevance to the individual country. Their primary purpose is to educate healthcare professionals and consumers about health promotion and disease prevention. In this way priorities in establishing dietary guidelines can address the relevant public health concerns whether they are related to dietary insufficiency or excess. In this context, meeting the nutritional needs of the population takes its place as one of the components of food and nutrition policy goals along with the priorities included in the FBDGs for improved health and nutrition for a given population.

The world nutrition and health situation demonstrates that the major causes of death and disability have been traditionally related to undernutrition in developing countries and to the imbalance between energy intake and expenditure (which lead to obesity and other chronic diseases - diabetes, cardiovascular disease, hypertension, and stroke) in industrialized countries. The tragedy is that many suffer from too little food while others have diseases resulting from too much food, but both would benefit from a more balanced distribution of food and other resources. Although the nature of the health and nutrition problems in these two contrasting groups is very different, the dietary guidelines required to improve both situations are not. Most countries presently have the combined burden of malnutrition from deficit and increasing prevalence of obesity and other chronic diseases from over consumption. The approaches to address the problems, nevertheless, should be country and population specific.

Although two-thirds of the world’s population depends on cereal or tuber-based diets, the other one-third consumes significant amounts of animal food products. The latter group places an undue demand on land, water, and other resources required for intensive food production, which makes the typical Western diet not only undesirable from the standpoint of health but also environmentally unsustainable. If we balance energy intake with the expenditure required for basal metabolism, physical activity, growth, and repair, we will find that the dietary quality required for health is essentially the same across population groups.

Efforts in nutrition education and health promotion should include a strong encouragement for active lifestyles. Improving energy balance for rural populations in developing countries may mean increasing energy intake to normalise low body mass index (BMI, weight/height 2 , calculated as kg/m 2 ), ensuring adequate energy stores and energy for appropriate social interactions. In sedentary urban populations, improving energy balance will mean increasing physical activity to decrease energy stores (body fat mass) and thus normalise BMI. Thus, the apparent conflicting goals - eradicating undernutrition while preventing overnutrition - are resolved by promoting sufficient energy for a normal BMI. Moreover, if we accept that FBDGs should be ecologically sustainable, the types and amounts of foods included in a balanced diet are not very different for promoting adequate nutrition in the undernourished and preventing overnutrition in the affluent.

This is well exemplified by the similarities in the FBDGs across countries, whether represented by pyramids, rainbows, dishes, pots, etc. It is obvious that consumption of excess energy will induce an increase in energy stores, which may lead to obesity and related health complications. Populations should consume nutritionally adequate and varied diets, based primarily on foods of plant origin with small amounts of added flesh foods. Households should select predominantly plant-based diets rich in a variety of vegetables and fruits, pulses or legumes, and minimally processed starchy staple foods. The evidence that such diets will prevent or delay a significant proportion of non-communicable chronic diseases is consistent. A predominantly plant-based diet has a low energy density, which may protect against obesity. This should not exclude small amounts of animal foods, which may make an important nutritional contribution to plant-food-based diets, as illustrated in the examples presented earlier. Inadequate diets occur when food is scarce or when food traditions change rapidly, as is seen in societies undergoing demographic transitions or rapid urbanisation. Traditional diets, when adequate and varied, are likely to be generally healthful and more protective against chronic non-communicable diseases than the typical Western diet, consumed predominantly in industrialized societies ( 17).

Reorienting food production, agricultural research, and commercialisation policies needs to take into consideration FBDGs, which increase the demand for a variety of micronutrient-rich foods and thus stimulate production to meet the consumption needs. Prevailing agricultural policies encourage research on and production and importation of foods, which do not necessarily meet the requirements of FBDG implementation. For example, great emphasis is placed on cereals, horticultural crops for export, legumes for export, non-food cash crops, and large livestock. Necessary policy reorientation is required to ensure increased availability of micronutrient-rich foods within the local food system. Norway has successfully implemented agricultural and food production policies based on a National Nutrition Plan of Action, providing economic incentives for the producer and consumer in support of healthful diets. The results speak for themselves, as Norway has experienced a sustained improvement in life expectancy and a reduction in deaths from cardiovascular disease and other chronic non-communicable conditions.

Recommendations for the future

The Consultation acknowledged the limitations in our knowledge of these important aspects, which affect nutrient utilisation and recommended that the International Food Data System (INFoods) effort led by FAO/UNU be strengthened. Special emphasis should be placed on the micronutrient composition of local diets as affected by ecologic setting analysis of food components (nutrients or bio-active components), which may affect the bio-availability and utilisation of critical micronutrients and the analysis of cooked foods and typical food combinations as actually consumed by population groups. In addition the development of FBDGs at the country level should be supported by UN agencies.

Future research

The following research needs were identified to facilitate the implementation of a food-based approach in the prevention of micronutrient deficiencies:

  • food data system development, which includes development of methodology for micronutrient composition of foods, organizing data retrieval, and reporting and dissemination through electronic means this effort should include phyto-chemicals, antioxidants, and other components which may affect health and nutrition, with special emphasis on local foods which may be important for given food cultures
  • identification and evaluation of optimal methods for cooking foods to preserve the nutrient value and enhance the bio-availability of micronutrients
  • development of better methods to preserve foods, especially micronutrients, at the household and community levels
  • identification and propagation of agricultural methods which will enhance the food yields, content, and biologic value of micronutrient-rich foods
  • identification of optimal food combinations and serving size which will be most effective in preventing micronutrient deficits and methods of promotion for these food combinations at the community level
  • development of agricultural research to support the implementation of FBDGs and
  • evaluation of the nutritional impact and cost benefit of food-based approaches in combating micronutrient deficiencies.

Note: Data in Tables 1 and 3

Note: Data in Tables 1 and 3

Note: Data in Tables 2 and 4

Note: Data in Tables 2 and 4

Table 1 : White rice and corn-tortilla based diets composition and nutrient density values per 1000 kcals for vitamin A, vitamin C, folate, iron and zinc



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