Iron metabolism is affected negatively by a diet high in phytate and fiber. Iron deficiency is the most prevalent nutritional problem in the world today. An iron deficiency has been associated with an irreversible impairment of a child's learning capabilities. The bioavailability of zinc, copper, and magnesium in cereal grains is generally low. The absorption of manganese, chromium, and selenium does not seem impaired.
Zinc deficiency can result in hypogonadal dwarfism in which there is arrested growth.
In countries with high cereal grain intake and hence low zinc absorption, hypogonadal dwarfism is nearly 3 percent and skeletal growth may be limited. The bioavailability of zinc from meat is four times higher than that from cereals. In addition, n-3 fatty acids are associated with reduced mortality from coronary heart disease. N-3 fatty acids are found in meat and especially oily fish. Infants deprived of DHA show both visual and neural cortical abnormalities.