What are Vitamins?

The vitamins are organic molecules required in low concentration for the proper functioning of the body. They cannot be generated in the organism and are taken into the body through the diet. The lack of proper vitamins results in diverse deficiency disorders. They are thus called essential nutrients. The important vitamins are vitamin A, vitamin B complex, vitamin C, vitamin D, vitamin K, and vitamin E.  

Classification of Vitamins

The vitamins usually don't exist as an individual molecule, where they can be identified as a set of molecules combined to perform a particular function in the body. They are associated with the regulation of distinct metabolic reactions occurring in the body. They support the action of enzymes and other proteins by acting as a cofactor and thereby activating or suppressing their functions.

Vitamins are mainly classified into two distinct types based on their biochemical nature in the body. They are called water-soluble and lipid-soluble vitamins.

The water-soluble vitamin encompasses vitamins B and C and the lipid-soluble vitamin include the vitamin A, D, E, and K. The water-soluble vitamins are eliminated daily from the body and they are required in higher amounts than the lipid-soluble vitamins.

The lipid-soluble vitamins are required in minor concentrations and they are not eliminated daily from the body. The elevation of the concentration of the lipid-soluble vitamins than the optimal level also results in the development of different disorders in the body.

The lack of sufficient vitamin concentration leads to the development of deficiency or disorders in the body. Serious vitamin disorders are found to be treated by employing vitamin tablets, which possess the deficient vitamins in higher levels such that the blood level of the particular vitamin can be elevated. 

"classification of vitamins”

Antivitamins are substances that resist the absorption of a particular vitamin in the body. This compound mimics the structure of the normal vitamins, where they resist the action of the respective vitamins in the body. 

Sources of Vitamins

The vitamin necessary for the body can be derived from natural food sources.

  • Vitamin A can be found in food sources including kale, spinach, sweet potatoes, and carrot.
  • Food products including fish, poultry, and meat are found to possess high levels of vitamin B12 or cobalamin and B3.
  •  Watermelon, soymilk, and food products such as cereals possess vitamin B1.
  • The vegetable oil, seeds, and nuts are good source of vitamin E.
  • Enriched grain (whole grain with added nutrients such as vitamins and minerals), milk, and yoghurt possess a good amount of vitamin B2 or riboflavin.
  • The food probiotics including mushrooms., chicken, broccoli, and whole grains possess vitamin B5 or pantothenic acid.
  • Legumes, bananas, and meat are the main sources of vitamin B6 or pyridoxine in the body.
  • Food products including fish, soybean and eggs are identified to contain vitamin B7.
  • The fortified grains (grains with added nutrients) and cereals possess vitamin B9 or folic acid.
  • Citrus fruits such as lemon, orange comprise the major source of ascorbic acid or vitamin C.
  • Egg, nuts such as walnut are the sources of vitamin D.
  • Green leafy vegetables such as spinach are the source of vitamin K.
"vitamin sources in diet”
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Deficiency Disorders

The lack of proper vitamin concentration in the body can lead to different disorders.

  • The reduced concentration of vitamin A in the body can result in a condition called xeropthalmia which causes the drying of the eye and the tear duct. This condition is followed by night blindness, where the individual lacks proper scotopic vision (vision under low light or dark).
  •  The lack of vitamin B1 causes a condition called beriberi resulting in serious weight loss and muscular weakness.
  • The riboflavin deficiency causes ariboflavinosis resulting in mouth sores mainly due to improper diet.
  •  A condition called pellagra results from vitamin B3 deficiency. The symptoms include weakness, loss of appetite, confusion, inflammation of the mucous membrane.
  •  The deficiency of pantothenic acid causes a condition called paresthesia (sensation on the skin such as tingling or burning without any physical cause), resulting in ischemic attacks and sclerosis.
  • The deficiency of pyridoxine and folic acid results in anemic condition. Megaloblastic anemia is the result of folic acid deficiency.
  • A condition called dermatitis (irritation of the skin) is caused due to vitamin B7 deficiency.
  • A condition called pernicious anemia and skin hyperpigmentation is caused by the deficiency of cobalamin.
  • Deficiency of ascorbic acid results in scurvy. Bleeding of gums occurs in scurvy. 
  • The bones are weakened during the shortage of proper vitamin D in the body and this condition is called rickets. Also, vitamin D deficiency can cause alteration in blood pressure (hypertension) and heart diseases.
  • Vitamin E deficiency causes hemolytic anemia resulting in the elevated depletion of red blood cells. The clotting is found to be delayed during vitamin K deficiency and this condition is called bleeding diathesis.
  • Ascorbic acid and vitamin E play an important role in neutralizing free radicals produced in the body
"vitamin D deficiency symptoms”


Vitamins perform diverse roles in the body. They have a positive effect on the growth and development of the child. The proper functioning of the immune system is also regulated by the action of the vitamins in the body. The lack of sufficient vitamins weakens the immune system and makes the body prone to different types of infections.

The fetus acquires certain important vitamins from the mother.These molecules aid in the proper division and differentiation of cells which further help in the growth and development of the fetus. Thus, the mother is forced on taking additional levels of vitamins in the food. 

If the mother fails to take proper levels of vitamins, it might cause developmental disorder in the offspring. The proper maintenance of the cells, tissue and organs in adults are also performed by the action of the vitamins in the body.

The lack of sufficient vitamins in the body will cause failure in the energy absorption process and thus weakens the functions of the body. 

Different vitamins have a diverse role in the body

  • Vitamin A is concerned with the regulation for proper scotopic vision in the eye.
  • Vitamin B has multiple functions and it mainly regulates the daily metabolism of the body.
  • Riboflavin is essential for body growth and protein metabolism.
  • Folic acid is essential for the development of erythrocytes and thereby increasing the transport of oxygen in the body. Folic acid also regulates the level of homocysteine in the body. For the development of the fetus's neural tube, folic acid is required. Folic acid helps in the regeneration of cells and tissues.
  • Ascorbic acid is found to function as an antioxidant in the body. Ascorbic acid is essential for growth and development, immune system functioning, and wound healing. Ascorbic acid is given for the treatment of scurvy.
  • Vitamin B12 reduces systolic blood pressure.
  • Vitamin D ensures the deposition of minerals in the bones and thus maintains the proper strength of the bones. Vitamin D is synthesized by the skin when exposed to sunlight.
  • Vitamin K has a major role in the production of the proper number of platelets in the body for aiding blood clotting. It is responsible for the release of sex hormones.

Context and Applications

This topic is significant in the professional exams for both undergraduate and graduate courses, especially for: 

  • Bachelor of science in Biochemistry
  • Bachelor of Medicine 
  • Bachelor of Surgery (MBBS)
  • Hypervitaminosis
  • Phytochemical
  • Human nutrition

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