For example, in the early 1900s, many children suffered from rickets, a vitamin D deficiency disease. A deficiency of thiamin causes the disease beri beri, and a deficiency of niacin causes the disease pellagra. Even in the 1930's, many people in this country died of a niacin deficiency. Starting in 1941, these vitamins were required to be added to refined flour, corn meal, and rice to prevent these diseases. Today, you often hear about nutrition studies before researchers have determined the results.
Antioxidant vitamins protect body cells from damage called oxidation.
Eating plenty of antioxidant vitamins may help prevent heart disease and cancer. But the most benefits come from diets high in foods that are good sources of these vitamins. This could be because there are other antioxidants in foods that we do not know about yet. That is why nutritionists recommend eating a variety of foods and trying to get your nutrients from foods and not supplements. Most people gain no extra benefits by taking vitamin supplements to get more vitamins than the recommended dietary allowance amounts.