Even small amounts of these substances are important, because they supplement What is obtained from other kinds of food. Vegetables differ greatly in their vitamin and mineral contents. Fortunately, however, some of the commonest and easiest to grow are the most valuable. Table 1 shows which of a number of commonly used vegetables are especially good sources of vitamin A, thiamin, ascorbic acid, riboﬂavin, calcium, and iron. Others, such as onions and beets, have great practical value in meals because of ﬂavor and color, even though they are not important for good nutrition.