Vitamins are a group of nutrients that are essential for normal cell function, growth, and development. Our bodies need only small amount of vitamins, that is why they are often referred to as micronutrients.
There are 13 essential vitamins, meaning they are needed for the body to function. They are vitamins A, C, D, E, K, and the B vitamins (thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B6, vitamin B12, and folate). Our bodies can synthesize small quantities of vitamin K and also vitamin D, when exposed to sun. Bacteria in the intestines can synthesize some of the B vitamins, but not in the amounts sufficient to meet daily needs. Thus majority of vitamins need to be obtained from food or multivitamin supplements.
Vitamins can be grouped into two categories: fat-soluble and water-soluble.
— There are four fat-soluble vitamins – A, D, E, and K. They need presence of fat to be properly adsorbed and utilized. Fat-soluble vitamins can be stored in the body’s fatty tissue and are eliminated slowly. Fat-soluble vitamins should not be consumed in excess since their over-accumulation can cause toxicity.
— There are nine water-soluble vitamins. The body uses water-soluble vitamins quickly and cannot store them. Any left over water-soluble vitamins are removed by the kidneys and excreted. Vitamin B12 is the only water-soluble vitamin that can be stored in the liver. Water-soluble vitamins need to be consumed in an adequate amount each day.