Vitamin D utilization by the body can be inhibited by an excessive consumption of cereal grains. Cereal grains are good sources of phosphorous, potassium, and magnesium, but are poor sources of sodium and calcium. Phytate is a salt or ester of phytic acid that is capable of forming insoluble complexes with calcium, zinc, iron, and other nutrients and interfering with their absorption by the body. Thus a high phytate content frequently induces bone mineral pathologies in populations dependent upon cereal grains as a primary food source. 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.