What are Vitamins?

In this post, you are going to learn about what vitamins are, how they function in the body, what happens if there are vitamin deficiencies in the body and what happens if there are an excessive amount of vitamins in the body, and what are essential vitamins?

What are vitamins and how do they work?


Vitamins are involved in almost every metabolic process in the human body. Since you need only small amounts of vitamins and minerals in your daily diet, they are classified as micronutrients. Despite this, they are one of our most important nutrients for optimal health and performance. And protein, fat and carbohydrates are classified as macronutrients since you need large amounts of them in your daily diet.

In 2 to 4 weeks, symptoms of a deficiency may appear for several vitamins, and major health problems may occur with prolonged deficiencies. Eating well and foods fortified with vitamins and minerals may help to alleviate major health conditions.

Vitamins are organic compounds and noncaloric substances. They are found in small amounts of most food and are also required in tiny amounts, microgram to milligram quantities in the human body. They are essential for optimal health and performance. Indeed, they are vital nutrients and an adequate supply of them must be present for the proper functioning of different physiological processes in the human body. Physiological processes are the processes in which organs, tissues, cells, and biomolecules work together to accomplish the complex goal of sustaining life. 

Vitamin functions as a coenzyme

Some complex chemicals known as enzymes are necessary for the basic physiological processes in the body. An enzyme is a protein that acts as biological catalysts (biocatalysts); catalysts accelerate chemical reactions. 

On the other hand, a coenzyme is an organic non-protein molecule that is generally required by an enzyme to perform its catalytic activity. For this reason, a coenzyme must generally be presented for an enzyme to function properly. Enzymes’ structure remains unaltered, while coenzymes are chemically changed throughout biological reactions. A coenzyme often contains a vitamin or some related compound.  

Enzymes are vital for several actions in the body. They act as a biocatalyst: to contract muscles, to break down food, to release energy stores in the body, to help grow, to help transport body gases such as carbon dioxide, to help clot blood and so forth. 

Vitamin functions as an antioxidant 

Substances known as free radicals are produced in various oxidative reactions in the human body. These free radicals contain unpaired electron in their outer orbit. An orbit is a path that is taken by an electron around the nucleus of an atom. And, an electron is a negatively charged subatomic particle that moves around (orbit) the nucleus (=centre) of an atom.

Free radicals are formed naturally in the body. They are unstable substances, with an unbalanced magnetic field. For this reason, they affect chemical reactions and molecular structure in the human body. These unstable compounds may be very reactive with body tissues. 

For normal cellular function, such as gene expression and muscle contractile force, the formation of free radicals such as superoxide anion (O2•-) and hydrogen peroxide (H2O2) during oxidative processes is necessary. Although oxidative processes are vital, some oxidations may cause cell membranes damage. The formation of these free radicals from oxidative processes may damage lipids, proteins, DNA and may be involved in the development of the neurodegenerative disease, cardiovascular disease and cancer. 

On the other hand, to stop damaging the cells from free radicals, the human cells produce several antioxidants enzymes. And to function properly, these enzymes must contain nutrients such as zinc, copper and selenium. Vitamins such as C, E and beta-carotene (an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits) also possess antioxidant features and qualities. 

Vitamin functions as a hormone

Some vitamins may be essential in the formation of different hormones, such as vitamin C in the formation of epinephrine, but are not referred to as hormones. Only vitamin D functions as a hormone in its active form. Vitamin D undergoes several transformations in the human body and promotes bone metabolism. It exerts its functions on various tissues after being produced in the kidney and flows in the blood. 

Although, vitamin A and K may be produced in the liver and intestines, respectively, and exert functions in other parts of the body, are generally not classified as hormones. 

Vitamins and their energy/caloric value

Vitamins do not have any caloric value. They do not have any significant role in the structure of the human body as do protein and some minerals. On the other hand, they are essential for the maintenance of optimal health ad regulating many functions in the human body.

Essential vitamins to human nutrition

An essential vitamin is one that can’t be synthesized in an adequate quantity in the body. For this reason, dietary intake lacking in an essential vitamin causes deficiency symptoms. And added back to dietary intake alleviates deficiency symptoms. Nine of these are water-soluble and the rest are fat-soluble. 

At present, there are 13 essential vitamins that the human body needs a sufficient amount of them. They are fat-soluble and water-soluble vitamins. The water-soluble vitamins are those that dissolve well in water including vitamin C and B vitamins. A variety of foods contain water-soluble vitamins. On the other hand, fat-soluble vitamins are those that dissolve well in lipids (fat) including vitamins A, D, E, and K, and obtained widely from the fat in our diet. A person can obtain all the essential vitamins from a well-balanced diet.

Although most vitamins must be taken from a diet, several of them may be formed from other ingested nutrients, by the action of ultraviolet rays from sunlight on our skin, or by some bacteria in the intestine. 

How do deficiencies of vitamins affect your health?

Vitamins and minerals deficiency symptoms may depend on the extent of the deficiency. To put it another way, the magnitude of micronutrients deficiency may be associated with the duration of undernourishment and inadequate vitamin and mineral intake. (In general, micronutrients are vitamins and minerals.) 

In the past, Recommended Dietary Allowances (RDA) for vitamins has been established to prevent vitamin-deficiency diseases such as Rickets, anaemia and scurvy. But the new Dietary Reference Intake (DRI) may be modified to help prevent chronic diseases, such as osteoporosis, or excessive intake of vitamins and associated health effects. 

There are four stages that may apply to micronutrients deficiency. The first three stages are known as latent vitamin/mineral deficiency or subclinical malnutrition. 

A preliminary stage: 

The preliminary stage of vitamin deficiency may occur when there is an extreme change in the diet. There could be an insufficient amount of vitamin in the diet in the preliminary stage. 

Biochemical deficiency

In this stage, the vitamins’ pool in the human body is reduced. Biochemical deficiency for some vitamins in the human body can be identified by blood test and tissue test. For instance, by the activity of an enzyme (glutathione reductase) in the red blood cells, the deficiency of riboflavin, known as vitamin B₂, can be detected. 

Physiological deficiency

The occurrence of some signs such as weakness, physical fatigue or loss of appetite is associated with physiological deficiency. Without a doubt, physical fatigue, loss of appetite and other deficiency symptoms would negatively affect your health and performance. 

Clinical manifest vitamin deficiency

In the fourth stage, a number of clinical symptoms are observed. For instance, anaemia, a medical condition in which your blood contains too few red blood cells, is a clinical symptom associated with a deficiency of some vitamins, such as vitamin B6, B12, and folic acid (B9). Without a doubt, both performance and health would be adversely affected by clinical manifest vitamin deficiency.  

How does excessive intake of vitamins affect your health?

On the other hand, it’s commonly rare to obtain excessive amounts of vitamins through the dietary intake to the point that health and physical performance is impaired. Additionally, to function properly, the human body may excrete those vitamins that are more than enough in the body. However, there is still a chance of hypervitaminosis for overconsumption of some vitamins. Hypervitaminosis is an abnormal state resulting from excessive intake of one or more vitamins in the body. In such an abnormality, a vitamin may function similar to a drug, not a nutrient, and cause toxic reactions. 

There are two reasons behind hypervitaminosis: a) excessive intake of vitamin supplements and/or b) some dietary practices. To put it another way, taking a vitamin supplement plus vitamin-fortified food on a regular basis could cause such condition in the body. This abnormality subsequently increases health risks.  

The bottom line

The vitamins comprise a diverse group of organic compounds that are nutritionally essential micronutrients. Some vitamins help regulate metabolic processes as coenzymes, others help protect cell membranes as antioxidants and Vitamin D in its active form acts even as a hormone. 

They do not have any key role in the structure of the body as do protein and some minerals. On the other hand, they are crucial for the maintenance of optimal health ad regulating many functions such as helping to regulate the energy processes in the body.

In the past, Recommended Dietary Allowances (RDA) for vitamins has been established to prevent vitamin-deficiency diseases such as Rickets, anaemia and scurvy. But the new Dietary Reference Intake (DRI) may be modified to help prevent chronic diseases, such as osteoporosis, excessive intake of vitamins and associated health effects. 

The four stages that have been described in defining a vitamin deficiency are the preliminary, biochemical, physiological and clinical manifest deficiency stages respectively. 


a human, a friend and a health coach who lives with you on this lovely planet, Earth, and is not identified with anything e.g. nationality, race, gender, etc.

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