VITAMINS

A vitamin is a micro-nutrient needed in smaller amounts through diet to keep the body healthy. There are two main types of vitamins according to their solubility. These are fat-soluble vitamins and water-soluble vitamins.

Fat Soluble vitamins mostly present in fatty foods and are soluble in fat also. These include Vitamin A, Vitamin D, Vitamin E and Vitamin K. As fats can be stored in body so these vitamins can also be stored in body if taken in amounts greater than necessary. Vitamin A can be stored in the liver for more than 5 months while Vitamin D storage in liver is sufficient for over 2 months. Some of them, especially vitamins A and D are very dangerous if taken in amounts greater than their upper limits.

Water Soluble vitamins are present and soluble in water. These are B vitamins and vitamin C. Due to their solubility in water, they can’t be stored in body in larger amounts. Therefore, these vitamins should be part of our daily diet in sufficient amount. Symptoms in Vitamin C deficiency can appear after few weeks while Vitamin Bs deficiency symptoms can occur after just few days. Vitamin B12 is an exception as it can be stored in liver for about 1 year in bound form although it is a water-soluble vitamin. 

Cooking Effects

Cooking of food effects loss of several vitamins in different percentages. The loss of vitamins B1, B3, B5, B9 and C is greater than 15% while the loss of vitamins A and E is about 10%. Cooking can also be beneficial for vitamins as it allows more vitamins to be absorbed by those foods which are otherwise difficult to absorb due to the hard structure of food. 

Exposure Effects

The exposure of foods to air, light and heat can also reduce vitamins in these foods from high degree to low levels.

Vitamins C and E are much affected by their exposure to air.

Exposure to light significantly reduces quantities of vitamins C, E, K, B6 and B12.

The percentage of vitamins C and B5 are greatly reduced by their exposure to heat while at high temperatures, vitamins B1 and B9 also reduce markedly.

Vitamin A is little affected by exposure to all these factors while their effect on certain vitamins is not properly known so far. 

Supplementation & Fortification

Apart of their natural presence in foods, these vitamins can also be obtained by vitamin supplements and fortification of certain foods.

Multivitamin supplements are available in the form of tablets, capsules, powders etc while certain foods are fortified or enriched with micro-nutrients including vitamins. These supplements and fortified foods can compensate the deficiency of vitamins and minerals in various groups of people especially old age people but their absorption in the body is limited and also their high doses can be harmful for body. Therefore, it is recommended to use natural foods to attain vitamins as much as possible while supplements and fortified foods should only be consumed when getting adequate vitamins from natural source is not possible.