The body requires micronutrients (small amounts
of essential nutrients) from diet because the body does not make all the products
it needs for optimum function. Micronutrients include vitamins A, B, and C,
folate, zinc, calcium, iodine, and iron. The 3 major micronutrient deficiencies
in the developing world are iron (see below), iodine (deficiency can cause goiter [enlarged thyroid gland] and can lead to death or
mental retardation for a developing fetus), and vitamin A. Vitamin A deficiency
is a serious worldwide medical problem because it is the leading cause of
preventable blindness in children. Breastfeeding is recommended to prevent
vitamin A deficiency in infants because breast milk is rich in vitamin A.
Food fortification and increasing the amounts of fruit and vegetables in the
diet are also important ways to reduce vitamin A deficiency in adults. A pregnant
woman is especially vulnerable to vitamin A deficiency because her developing
fetus uses what vitamin A is available in her body.