Pantothenic acid One of the B vitamins. Pellagra A deficiency disease that occurs in people who eat low-protein diets that are deficient in niacin. Pellagra was once common among poor people in the southern U.S. who lived on diets that consisted primarily of corn. A severe disease caused by the inability of the body to absorb vitamin B 12 from the digestive tract into the bloodstream. Protein A complex, nitrogen-containing substance that is found in food and is essential for the functioning of the human body.
Protein molecules consist of long chains of building blocks called amino acids.
Some of these amino acids can be manufactured in the human body. Others must be supplied by the diet. The body breaks down food proteins into their amino acid constituents and then reassembles the amino acids into the proteins needed for normal functioning. Provitamin A compound that the human body can convert into a vitamin. For example, beta-carotene is a provitamin because the body can convert it into vitamin A, as needed.