A balanced diet rich in grains vegetables, fruits, dairy products, meat products, poultry, fish, beans, etc. provide almost all the vitamins required for a healthy life. Some of the vitamins are believed to prevent certain chronic diseases as well. The 13 vitamins commonly required provides proper bodily conditions if taken in adequate amounts. vitamins help to regulate the metabolic activities and prevention of deficiency diseases such as rickets, scurvy, beriberi, etc. The intake of vitamins in more than required amount and when intake is not sufficiently enough; harm results than good.
Calcium can only be absorbed into the body with the help of vitamin-D. Osteoporosis and even colon cancer can be prevented by vitamin D. Our daily equirement is 5 micrograms of Vitamin-D till we are 50. Then it has to be increased to 10. Most of the requirements are manufactured by the body itself in presence of sunlight.A pregnant lady requires 400mcg of folic acid daily which is provided by a rich citrus fruit, grains and leafy vegetable diet.Folic acid can prevent anencephaly and spina bifida; two common neural-tube birth defects in newborns.
Cervical cancer prevention, maintaining the integrity of DNA and preventing abnormal cell growth are important duties performed by folic acid.This along with vitamin B6 and B12 helps to fight heart diseases by preventing the accumulation of homocysteine, a metabolic byproduct of amino acid.If the level of omocysteine goes high, it will lead to the formation of blood clot leading to heart failure and stokes. Whole wheat, peanuts, banana, soybean, fish, chicken and meat are good sources of B6.Free radicals; the unstable oxygen molecules inside human body and in the air around, pose threat to eyes, blood vessel walls and even DNA causing cataract, heart disease and cancer.
Vitamin C, E and beta carotene synthesized by our body itself has the ability to neutralize these free radicals. Studies show that a daily supply of 100IU of vitamin E reduces heart diseases considerably. They also seem to guard the blood vessels from damage caused by the LDL cholesterol. Vitamin C is being concentrated to 60 times more in the lens of human eyes than that of blood so as to ensure protection from UV. After the age of 50, immunity goes down thereby increasing the risk of diseases. Vitamins C, E, B6 and B12 help to revive the immune system.

Taking in of supplements alone cannot create miracles in our body. Orange juice is good choice of vitamin C. The diet should be supplemented with enormous supply of vegetables and fruits which are loaded with disease-fighting phytochemicals.