Role of vitamins in human body

health Jun 30, 2021
Photo by Sam Moqadam / Unsplash

Vitamins are organic substances, required in small amounts for body functioning and good health.
Unlike carbohydrates, proteins and fats, vitamins do not provide calories. However, they help the body to use the energy from food.
The human body can manufacture only a few vitamins.
Microorganisms in the intestine commonly known as "gut flora" produce vitamin K and biotin.
Vitamin D is synthesized in the skin with the help of the natural ultraviolet wavelength of sunlight.
Human body can produce some vitamins from precursors they consume.
Most vitamins must be acquired from food. Food is the best source of vitamins and minerals, and one may get vitamins by eating a healthy, balanced diet.

Role of vitamins in human body

Vitamins allow the human body to grow and develop. They play an important role in the functioning of various processes inside the body such as metabolism, immunity, tissue growth and differentiation.

Once growth and differentiation are completed, vitamins remain essential nutrients for the healthy maintenance of the cells, tissues, and organs.
They also enable the human body to efficiently use chemical energy provided by food, and to help process the proteins, carbohydrates, and fats of food.
They act as catalysts and help the metabolic activities taking place inside the body.
They also act as coenzymes and help in the transportation of various chemical groups between the enzymes.
Vitamin B7 also known as biotin is responsible for the formation of fatty acids. Thus, Vitamin forms an important part of our diet.

Vitamins are classified in two categories: water soluble and fat soluble.
In humans there are 13 vitamins: 4 fat-soluble (A, D, E, and K) and 9 water-soluble (8 B vitamins and vitamin C).
Digestive system requires all essential vitamins. However, B vitamins and vitamin C play valuable roles in digestive health.
Water-soluble vitamins dissolve easily in water and are readily excreted from the body.
Fat-soluble vitamins are absorbed through the intestinal tract with the help of lipids (fats). Vitamins A, D, E and K are stored in significant amounts, in the liver. Because they are not water soluble, accumulate in the body and may lead to hypervitaminosis. So, Fat-soluble vitamin regulation is important in cystic fibrosis.

Water soluble vitamins

Vitamin B1, also called thiamine, helps the body to convert carbohydrates into energy during digestion.
Vitamin B3, or niacin, helps normal breakdown of carbohydrates, fats and alcohol.
Vitamin B6, or pyridoxine, promotes protein digestion.
Vitamin B, folate, or folic acid, is associated with reduced risk for colon cancer.
Vitamin B7 also known as biotin is responsible for the formation of fatty acids.
Niacin is produced from the amino acid tryptophan of the body.
To meet B vitamin needs, eating a diet rich in whole grains, beans, seafood, dairy products and leafy green vegetables is required.
Vitamin C is an antioxidant. It increases iron absorption and is essential for gum and tooth health.
Vitamin C sources include citrus fruits, tomatoes, strawberries, bell peppers and sweet potatoes.

Fat soluble vitamins

Photo by Ryan Kwok / Unsplash

Vitamin A is needed for healthy vision, bone growth, reproduction and the immune system. It is manufactured in the body from substances called beta-carotenes, which are found in dark green, orange and yellow vegetables, such as spinach, carrots, broccoli, cantaloupe, mangos, apricots, vegetable soup and tomato juice, meat and dairy products such as liver, beef, chicken, whole milk and eggs.

Vitamin D, functions as hormone, regulators of mineral metabolism, or regulators of cell and tissue growth and differentiation. Vitamin D is present in body tissues and blood. Although vitamin D is obtained from foods, human body also produces it on exposure to sun. Consuming vitamin D rich foods and supplements requires fat sources, such as olive oil, salmon or nuts, because fat enhances its absorption.

Vitamin E protects red blood cells and is important in reproduction. It also acts as an antioxidant, preventing cell damage by ‘free radicals’ that are associated with aging and certain diseases.
Vitamin E sources are vegetable oils, vegetables, cereals, wheat germ, whole-grain products, avocados and nuts.

Vitamin K is involved in blood clotting. Dark green, leafy vegetables, pork, liver and other meats are the main source in the diet. In addition, bacteria in the gut can make vitamin K, which is absorbed into the blood.


Deficiencies of vitamins are classified as primary and secondary.
A primary deficiency occurs when an organism does not get enough of the vitamin in its food.
A secondary deficiency may be due to an underlying disorder that prevents the absorption or use of the vitamin, due to smoking, excessive alcohol consumption, or the use of medications that interfere with the absorption or use of the vitamin.
People who eat a varied diet are unlikely to develop a severe primary vitamin deficiency.
Well-known human vitamin deficiencies involve thiamine -beriberi, niacin –pellagra, vitamin C-scurvy, and vitamin D- rickets.


A. Sandhya

M.Sc Zoology

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