Vitamins are nutrients which are very important for good health. They are required in small amounts. Our body cannot synthesize them on its own; therefore, they must be provided by food. The lack of vitamins in the diet leads to various deficiency diseases. Vitamins are divided into two groups:
1) Fat soluble vitamins: This group includes vitamins A, D, E and K. They require the presence of fat in diet for their proper absorption. As they are fat soluble, the excess amounts of these vitamins present in food are stored in the body along with the fats, especially in the liver.
2) Water soluble vitamins: These are vitamins of the B-complex group and vitamin C. They are soluble in water and therefore, the excess amounts of these are excreted through urine. As they cannot be stored in the body for long, we must include them in adequate amounts in our daily food.
Vitamin A
We get vitamin A from foods in two forms:
1) Retinol which is also commonly called vitamin A, is the form in which the vitamin is utilized by the body. It is present mainly in animal foods.
2) Carotene which is the precursor of retinol or vitamin A, is present in plant foods. In the body this gets converted to retinol or vitamin A and is then used.
Sources:
Foods which are a good source of retinol or vitamin A are milk, curd and eggs; liver and fish liver oils are very rich sources of vitamin A. Carotene is present in green leafy vegetables like radish leaves, spinach etc. It is also obtained from red and yellow vegetables like carrots, tomatoes, pumpkin and fruits like papayas and mangoes. Some carotene is also present in milk, eggs and butter along with retinol.
Functions:
Vitamin A is very important for our eyes. You must have noticed that we can see even when the light is dim, e.g., in a slightly darkened room. This is made possible by the presence of vitamin A. Vitamin A also keeps the eyes healthy, moist, clear and protected from infections.
Vitamin A is important for the healthy development of the skin and of the mucous lining of the gastro-intestinal tract and genitor-urinary tract. It is also necessary for normal growth and development of the body. Deficiency of vitamin A can affect eyesight and skin.
Vitamin D
We get vitamin D mostly from a precursor (7-dehydro cholesterol) which is present under our skin. When the sun’s rays fall on the skin, this precursor gets converted to vitamin D. We also obtain it in small amounts from some foods.
Sources:
We mainly depend on action of sunlight on the precursor under our skin to meet our needs of vitamin D. We also get the vitamin from foods like liver, fish, egg yolk, milk and butter. Fish liver oils are a very good source of the vitamin.
Functions:
Vitamin D is important for the proper absorption of calcium in our body and its deposit in the bones and teeth. It helps in the formation of strong bones and healthy teeth. Deficiency of vitamin D can affect the growth and strength of bones and teeth.
Vitamin E
This is also a fat soluble vitamin. It is important in the healthy functioning of the reproductive system in the body. Vitamin E protects the heart, improves the immune system, protects against cataracts. A deficiency of this vitamin, therefore, can lead to problems related to the reproductive organs.
However, it is very rare that a deficiency of this vitamin is seen because it is present in many foods that we commonly eat. Also, it is required by the body in small amounts and so the need can be easily met. Whole grain cereal, soybean, peanuts, coconut, etc are good sources of vitamin E.
Vitamin K
This helps to bring about clotting of blood and thus stops the loss of blood from our body whenever there is an injury or cut.
A little amount of vitamin K is synthesized in our body by some micro-organisms present in our intestines.
The food sources are green leafy vegetable like spinach, radish leaves etc.
When there is deficiency of vitamin K, the body loses a lot of blood due to a cut or injury.
Vitamins of the B-complex group
These are a group of vitamins which are present in some types of food. As they are soluble in water, they are easily lost by throwing the water in which food has been soaked or cooked. There are a number of vitamins in this group and the most important ones are:
o Vitamin B1 or Thiamine
o Vitamin B2 or Riboflavin
o Vitamin B3 or Niacin
o Folic Acid
o Vitamin B12
Sources:
Whole cereals and pulses and nuts are good sources of Thiamine and Niacin; sprouted pulses are also rich in these vitamins. Animal foods like eggs, liver, brain and kidney are very good sources or B-complex vitamins. Milk and its products are especially important for Riboflavin. Green leafy vegetables are a good source of Riboflavin and Folic acid.
Functions:
The B-complex vitamins are essential for normal growth and development. They are important for the healthy functioning of vital organs, like the heart, nerves and brain and also for healthy skin, eyes and gastro-intestinal tract. Vitamins B12 and folic acid are important in the normal formation of the red blood cells in our body.
Vitamin C
It is also known as ascorbic acid. It is easily destroyed on exposure to heat and light. We mainly get it from fruits and vegetables.
Sources:
Vitamin C is often called the fresh food vitamin. This is so because it is very easily destroyed on cooking. Citrus fruits like oranges, sweet lime and lemons are a very good source of vitamin C. Sprouted grams, guava and pineapple are also rich in vitamin C. other good sources are vegetables like cabbage, green chilies, tomato and green leafy vegetables.
Functions:
Vitamin C is important in the body for the healthy development of our teeth, gums and skin. It also gives us the ability to protect ourselves against infections.
Carbohydrates Fats Proteins Water