The study of vitamins and minerals has been on for a fair amount of time now and a lot is known about the roles of each in a body. We also know a lot about what happens if too much or too little of any one is ingested. Research is an ongoing process to learn as much as posible about the effects of these vitamins and minerals on the physiological functioning of the body. The Food and Nutrition Board of the National Research Council of the National Academy of Sciences are constantly reviewing the Recommended Dietary Allowances (RDA).
All vitamins can be obtained directly from food with the exception of vitamins D, B5 and B7 which are obtained in part from different sources. B5 or Pantothenic acid can be absorbed by the body from a ten minute stint in the midday sun which will give an adult half of the required amount. The remainder has to be absorbed from fatty fish like salmon and tuna or dairy products. A bit gets produced by the body by normal intestinal bacteria.
Minerals originate from the soil and water and are also found in plants and animals. Macro minerals are those which are needed by the body in large quantities like magnesium, calcium and phosphorous. Micro minerals are those which are required in small quantities like fluoride, zinc, selenium, iron, etc and both together add up to18 in number.
Ideally the required nutrition should come from the diet itself which means the diet has to be a balanced one. But studies have shown that less than 1/3 adults have the requisite 5 servings of fruits and vegetables. People who need to consume more are children and pregnant women, alcoholics and those who have diseases that would inhibit the absorption of vitamins by the body. As also post menopausal women who now have to prevent osteoporosis. Older people tend to have fewer calories than what is their daily requirement. They depend on supplements for their vitamin deficiency.
Supplements are being promoted as an insurance against poor dietary habits and these supplements are fast becoming a habit and this is being stretched to include proteins. There are supplements for athletes that profess to improve their performance. Products declaring that they are best for curing different problems are freely available in the market today. They range from problems like depression to cancer to indigestion to even arthritis. Others talk of benefits in anti-aging or the elimination of toxins, but one has to be careful as the claims made are rarely substantiated by actual fact.