At a glance
In brief
Any of a group of substances that, in very small amounts, are essential for normal growth, development and metabolism. They cannot be made in the body (with a few exceptions) and must be obtained from the diet.
In brief
Any of a group of substances that, in very small amounts, are essential for normal growth, development and metabolism. They cannot be made in the body (with a few exceptions) and must be obtained from the diet.