What are Types of Vitamins

Presentation Notes on Vitamins Imbalance / Toxicity, Diet Chart  Classifications for Medical, Biology Students & Kids in word/ .pdf /.ppt Format

Vitamins can be divided into 2 main groups

1. Fat-soluble vitamins:-

  • Vitamin A, D, E and K. These are
  • Stored in the liver
  • Not absorbed or stored easily
  • Sometimes toxic in excess (particularly A and D)

2. Water-soluble vitamins:-

  • Vitamin B-complex and C. These are
  • Not stored extensively
  • Required regularly in the diet
  • Generally non-toxic in excess (within reason)
  • All B vitamins are coenzymes in metabolic pathways.

Each vitamin has a specific function to perform and deficiency of any particular vitamin may lead to specific deficiency diseases. For some vitamins (e.g., vitamin E), no deficiency disease is yet known.

Digestion and Absorption

Vitamins are released from food during the digestive process but are not digested.

Water-soluble vitamins (vitamin B-complex and C) that are utilized by the body for metabolic processes are absorbed through the small intestine. Any excess that is not used right away is excreted by the kidneys in the urine.

Fat-soluble vitamins (vitamins A, D, E, and K) are absorbed with dietary fats through the small intestine. After absorption, they are sent to the liver and fat depots and circulate through the blood with the help of chylomicrons and lipoproteins.

(Leevy et al 1968) Patient with liver disease may exhibit reduced storage, reduced hepatic intake, and diminished consumption of vitamins.

Toxicity / lmbalance

Eating too many fortified foods or taking a megadose of vitamin supplements—more than the recommended daily intake can produce toxic effects. Fat-soluble vitamins are more toxic than water-soluble vitamins because they can be stored and accumulate in adipose tissues. There is less danger of water-soluble vitamins exerting a toxic effect on the body because storage is limited and usually the excess is excreted on a daily basis.

Vitamin D is the most toxic of all vitamins because of its ultimate effect on the human body.  Vitamin D enhances the absorption of calcium, and so an excess of vita­min D causes an excess of calcium circulating in the blood, which is detrimental to the heart.

Two water-soluble vitamins can be somewhat toxic: vitamin B-6 and niacin. Both can have detrimental effects if the amount ingested is more than the kidney can handle and excrete.

During lactation, vitamin A, C and E are required more when compared to during pregnancy.

Human breast milk contains limited quantities of vitamin C and D.

Recommended dietary allowances for Indians10 ( ICMR 1990 )

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