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I have found the following definition on Wikipedia:
An organic chemical compound (or related set of compounds) is called a vitamin when the organism cannot synthesize the compound in sufficient quantities, and it must be obtained through the diet;
That doesn't seem to exclude essential amino acids and essential fatty acids though, and those are also organic chemical compounds that by definition can't be synthesized in sufficient amounts.
So is the definition incomplete?
Generally speaking, bulk essential nutrients (e.g. amino acids, fatty acids) are used stoichiometrically to form macro cellular structures and are 'baked in' to the structures or compounds they are used to make. Once those structures are destined for degradation, sometimes the bulk essential nutrients can be recovered and reused in the synthesis of other structures or compounds, but catabolic elimination from the organism is always an option that yields useful energy.
Vitamins, on the other hand, are usually used catalytically. Vitamins are not 'baked into' the compounds they help make or process; vitamins transiently participate in the reactions required to make or regulate a compound or structure, but don't ultimately get 'used up' by that process.
Ultimately, vitamins don't have a bulk energetic value to a cell. For instance, once vitamin E (α-tocopherol) is oxidized, its only fate is to be excreted as waste. Fatty acids and amino acids, once destined for degradation, have their remaining chemical energy extracted prior to excretion of their downstream waste products.
It is philosophically interesting to remark on the diversity of bulk biomolecular building blocks that are still necessary for some organisms to obtain from their environment. Not all of them get called vitamins.
It's just naming convention. We recognize, officially, the 13 vitamins based on activity, but we intentionally classify amino acids, etc. as such instead of as vitamins. It's just one of those things that people stick to so that it's standard, such as beverages as a blanket term for certain drinks but not for every type of fluid. (maybe that's a bad example, but hopefully you get the idea)
noun, plural: vitamins
A low molecular weight organic compound that is essential for normal growth and metabolic processes and is required in trace amounts
A vitamin is an organic compound that is essential for the normal growth and metabolic processes of an organism. The organism is not capable of synthesizing an adequate amount of such chemical compound and therefore must obtain it in its diet. Another important feature of an organic compound to be considered as a vitamin is to be required in only limited but adequate amount. The term vitamin was first used by Polish biochemist Kazimierz Funk. It came from vitamine, which in turn was derived from Latin vita, meaning life, and amine after the initial discovery of thiamine (formerly aberic acid) when it was thought that all vitamins are amines. 1, 2
There are various types of vitamins. In humans, there are 13 vitamins essential for growth and metabolism. Four of them are fat-soluble, meaning they are soluble in fat or nonpolar solvents. The other nine vitamins are water-soluble since they readily dissolve in water.
- Fortified vitamin d milk
- Vitamin d deficiency
- Vitamin c deficiency
- Bacterial Vitamin H1
- Vitamin e deficiency
- Vitamin b1
- Vitamin k4
- Vitamin k
- Vitamin c
- Vitamin a
- Vitamin k2
- Fertility vitamin
- Vitamin d
- Vitamin B2
- Vitamin G
- Vitamin M
- fat-soluble vitamin
- water-soluble vitamin
1 Iłowiecki, Maciej (1981). Dzieje nauki polskiej. Warszawa: Wydawnictwo Interpress. p. 177.
A vitamin is an organic molecule (or related set of molecules) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrients cannot be synthesized in the organism, either at all or not in sufficient quantities, and therefore must be obtained through the diet. Most vitamins are not single molecules, but groups of related molecules called vitamers. For example, vitamin E consists of four tocopherols and four tocotrienols.
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Iodine is a mineral found in some foods. Your body needs iodine to make thyroid hormones. These hormones control your body’s metabolism and other functions. They are also important for bone and brain development during pregnancy and infancy.
Source: National Institutes of Health, Office of Dietary Supplements
Iron is a mineral. It is also added to some food products and is available as a dietary supplement. Iron is a part of hemoglobin, a protein that transports oxygen from the lungs to the tissues. It helps provide oxygen to muscles. Iron is important for cell growth, development, and normal body functions. Iron also helps the body make some hormones and connective tissue.
Source: National Institutes of Health, Office of Dietary Supplements
The Chemical Structures of Vitamins
Click to enlarge
Vitamins are an important part of our diet, but you probably haven’t given a great deal of thought to their chemical structures. This graphic shows chemical structures for all 13 vitamins though there can be some variability in these structures in sources of the vitamins, these are generally representative. They perform a range of roles in the body below is a brief discussion, and a look at the evidence for taking vitamin supplements.
First, it’s worth discussing what makes a chemical compound a vitamin. A vitamin is defined as any organic compound that a living organism requires, but which it is not capable of producing itself, or cannot produce in the amounts required by the body. As far as the definition for vitamins goes, this doesn’t include the other essential nutrients that are found in our diet, such as amino acids, fatty acids, carbohydrates and minerals.
Currently, there are 13 recognised vitamins: vitamins A to E, including a range of B vitamins, and vitamin K. The slightly odd gap in lettering between E and K is a consequence of changes in designations of vitamins for example, vitamin B7, biotin, was previously referred to as vitamin H. The compounds originally designated as vitamins F to J were either redesignated, or subsequent research led to them no longer being classified as vitamins.
Generally, we can stick all of the vitamins into two broad categories. The fat soluble vitamins, vitamins A, D E, and K, can be stored by our bodies in the liver or in fatty tissues. They are stored until they’re required, which consequently means they generally don’t need to be ingested as frequently. Water soluble vitamins, on the other hand, are not stored in the body. As such, they must be a regular part of the diet in order to avoid deficiency. Conversely, the fact that water soluble vitamins aren’t stored in the body makes it harder to overdose on them, which can also have detrimental effects.
Some vitamins are chemically simpler than others vitamin D, for example, occurs naturally only in the form shown in the graphic. Others, such as vitamin E, can come in the form of a range of structurally similar compounds, with the exact substituents varying. The active form of vitamins in the tissues of mammals can also be marginally altered from the manner in which it occurs in foods.
Vitamins have a wide range of roles within the body, a brief summary of which is given in the graphic above. For example, a number of the B vitamins are important for making red blood cells, and metabolism of a variety of compounds during digestion. Others have uses in more specific parts of the body for example, vitamin A is important for our eyesight, whilst vitamin K plays a major role in the clotting of blood. Similarly, deficiencies of vitamins can also have effects a lack of vitamin C can lead to scurvy, the bane of sailors before the role of vitamin C was understood. A lack of vitamin K can cause bleeding problems, which is why newborn babies are given a shot containing the vitamin, preventing bleeding on the brain and the subsequent potential brain damage.
So, should you take vitamin supplements to avoid these deficiencies? If you have a balanced diet, then chances are you’re already getting these vitamins in the required quantities. There are cases where supplements are recommended for those who are at risk of deficiency however, for the general population, the evidence for taking them might be a little shaky. A review of studies involving a sum total of 400,000 people taking vitamin supplements found that they did little to prevent chronic disease or death, and concluding that if multivitamin supplements have any effect, then it is a very small one.
If you want find out much more about the sources and roles of the various vitamins, check out the links provided below.
Words nearby fats
Fats are greasy substances found in the tissues of animals and some plants.
Many of the foods we eat contain these fats. Foods from animals, such as meat, milk, and eggs, all contain fats. So do some plant-based foods, such as nuts, avocados, and olive oil.
The singular form fat can be used to collectively refer to the same thing. The body stores and uses fat for energy.
The plural form fats is most often used in the context of nutrition. There are several different kinds of fats, such as saturated fats, unsaturated fats, and trans-fats, each of which can have different effects on a person’s nutrition and health.
In general, it’s usually recommended not to consume too much fat. However, some fats are necessary in a diet because they help the body to absorb vitamins. The nutrition label on food products usually tell you exactly how much fat and what kinds of fats are in them.
Example: This diet is based on avoiding foods that are high in fats.
Coenzymes: Meaning and Classification | Enzymes
Many reactions of substrates are catalyzed by en­zymes only in the presence of a specific non-protein organic molecule called the coenzyme. Coenzymes combine with the apoenzyme (the pro­tein part) to form holoenzyme. The coenzymes are also regarded as co-substrates.
Coenzymes are heat-stable, dialyzable non­-protein organic molecules and the prosthetic groups of enzymes.
Classification of Coenzymes:
I. Based on chemical characteristics:
A. Containing an aromatic hetero ring.
B. Containing a non-aromatic hetero ring. Biotin, lipoic acid.
Sugar phosphate, coenzyme Q.
II. Based on functional characteristics:
A. Group transferring coenzymes:
3. Thiamine pyrophosphate (TPP).
B. Hydrogen transferring coenzymes:
1. Nicotinamide adenine dinucleotide (NAD) and Nicotinamide adenine di­nucleotide phosphate (NADP).
2. Flavin adenine dinucleotide (FAD) and flavin mono-nucleotide (FMN).
III. Based on nutritional characteristics:
(a) Containing B vitamins:
1. Their function is usually to accept atoms or groups from a substrate and to transfer them to other molecules.
2. They are less specific than are enzymes and the same coenzyme can act as such in a number of different reactions.
3. The coenzymes are also attached to the protein at a different but adjacent site so as to be in a position to accept the atoms or groups which art removed from the substrate.
4. NAD and NADP coenzymes function as hydrogen acceptors in dehydrogenation reactions.
5. The chief function of CoA is to carry acyl groups and they are used in the oxidative decarboxylation of pyruvic acid and syn­thesis of fatty acids and acetylation.
6. The function of TPP (co-carboxylase) is to carry ‘active aldehyde’ (R. CH(OH) ) group.
7. The chief function of pyridoxal phosphate (B6-PO4) is involved in transamination re­actions.
8. The chief function of tetrahydrofolic acid is expressed as a carrier of formate and it is used in the synthesis of purines and pyrimidines.
Coenzyme A (CoA):
1. It is composed of adenosine triphosphate (ATP), pantothenic acid and β-mercaptoethalamine. So it is the coenzyme form of pantothenic acid, a vitamin.
2. It is a group transferring coenzyme.
3. The reaction group is the sulfhydryl (-SH) group.
4. The acyl group is accepted by the sulfhydril group to form acetyl coenzyme A (CH3CoS.CoA). The acyl coenzyme de­rivatives are the high energy compounds.
1. Carrier of acyl groups, e.g., acetyl, sccinyl, benzoyl.
2. Some of the pantothenic acid is bound to protein in the form of “acyl carrier pro­tein”. This can be regarded as coenzyme A in which the adenine dinucleotide is replaced by protein. ‘”Acyl carrier protein” chiefly functions in the synthetic proc­esses, e.g., of fatty acids and cholesterol.
It is required in the oxidative decarboxy­lation of pyruvic acid and α-ketoglutaric acid, in the breakdown and synthesis of fatty acids and in the synthesis of choles­terol which is involved in bile acids, bilp salts, steroid hormones and vitamin D for­mation.
4. It is used for conjugation with amino com­pounds to form N-acetyl compounds and in the formation of hippuric acid (Ben­zoyl glycine).
5. It is involved in the formation of ketone bodies.
6. It is used in the formation of acetyl choline.
7. It is finally oxidized to CO2, H2O and ATP via citric acid cycle.
Monounsaturated fat is a type of fat is found in avocados, canola oil, nuts, olives and olive oil, and seeds. Eating food that has more monounsaturated fat (or "healthy fat") instead of saturated fat (like butter) may help lower cholesterol and reduce heart disease risk. However, monounsaturated fat has the same number of calories as other types of fat and may contribute to weight gain if you eat too much of it.
Source: National Institute of Diabetes and Digestive and Kidney Diseases
Nutrients are chemical compounds in food that are used by the body to function properly and maintain health. Examples include proteins, fats, carbohydrates, vitamins, and minerals.
Source: National Institutes of Health, Office of Dietary Supplements
Nutritional patterns in the living world
Living organisms can be categorized by the way in which the functions of food are carried out in their bodies. Thus, organisms such as green plants and some bacteria that need only inorganic compounds for growth can be called autotrophic organisms and organisms, including all animals, fungi, and most bacteria, that require both inorganic and organic compounds for growth are called heterotrophic. Other classifications have been used to include various other nutritional patterns. In one scheme, organisms are classified according to the energy source they utilize. Phototrophic, or photosynthetic, organisms trap light energy and convert it to chemical energy, whereas chemoautotrophic, or chemosynthetic, organisms utilize inorganic or organic compounds to supply their energy requirements. If the electron-donor materials utilized to form reduced coenzymes consist of inorganic compounds, the organism is said to be lithotrophic if organic, the organism is organotrophic.
Combinations of these patterns may also be used to describe organisms. Higher plants, for example, are photolithotrophic i.e., they utilize light energy, with the inorganic compound water serving as the ultimate electron donor. Certain photosynthetic bacteria that cannot utilize water as the electron donor and require organic compounds for this purpose are called photoorganotrophs. Animals, according to this classification, are chemoorganotrophs i.e., they utilize chemical compounds to supply energy and organic compounds as electron donors.
Despite wide variations in the nature of the external energy source utilized by various organisms, all organisms form from their external energy source an immediate source of energy, the chemical compound adenosine triphosphate (ATP). This energy-rich compound is common to all cells. Through the breaking of its high-energy phosphate bonds and thus by its conversion to a less energy-rich compound, adenosine diphosphate (ADP), ATP provides the energy for the chemical and mechanical work required by an organism. The energy requirements of organisms can be measured in either joules or calories.
Based on the fertilization of the flowers, fruit is classified as &minus
True Fruits &minus When the fruit forms in the ovary (of the flower) through fertilization is known as true fruit. E.g. strawberry.
False Fruits &minus The fruits formed some other means (other than ovary), such as calyx, thalamus, corolla, etc. known as false fruits. E.g. pear, apple, etc.
Further, because of verities and diversities, fruits are classified as &minus
Simple fruit &minus It can be either dry fruit (such as coconut, walnut, etc.) or fleshy (such as gooseberry, tomato, etc.).
Aggregate fruit &minus It is formed from single flowers, which have multiple carpels. E.g. raspberry.
Multiple fruit &minus It is formed from a cluster of flowers, e.g. pineapple, mulberry, etc.