|Nutrition and Nutrients|
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Iron needs to be absorbed and maintained in the body within a narrow range for optimal health. Iron absorption is regulated. Several different proteins have been identified as contributors to the process. Iron disorders are generated by both Fe deficiency and Fe overload.
Iron deficiency is the best advertised, and perhaps most common nutrient deficiency. The advertised image of "tired blood" has prompted generations of tired people to take iron supplements. Iron deficiency causes a characteristic anemia with small pale red blood cells, deficient in oxygen-carrying hemoglobin. Iron supplementation cures this anemia, and is one of the more gratifying treatments in the medical repertoire. Iron is stored in the bone marrow, and once full, can supply enough iron for several months of dietary iron deficiency. Women store less iron than men, and lose iron monthly in menstrual blood, and are therefore much more likely to suffer iron deficiency than men. Infants are born with iron stores sufficient for 4-6 months, and thereafter need to ingest sufficient iron to supply absorption of 0.5-0.8 mg/day. Both breast milk, and cow's milk need iron supplementation, after 4 months.
Iron absorption is impaired by teas, coffee, cereal grains, antacids, and ulcer medications (cimetadine). Absorption is enhanced by VM.C, fish, and meat. Iron deficiency is routine in patients with inflammatory bowel disease, especially Crohn's disease. Injection of iron into buttock muscles is often necessary when iron absorption is blocked by a diseased small intestine. Diets often do not supply the RDA level of 10 mg/day, and iron supplements for high risk groups, especially menstruating, and pregnant women, infants and children with limited diets. Marginal iron deficiency, before the appearance of anemia, can impair exercise tolerance via malfunction of iron-using enzymes in the energy system. Increased lactic acid production with exertion is one of the markers of subtle iron deficiency. Iron intake of athletes should be carefully monitored. High doses of iron are definitely to be avoided. Iron may have a negative side. Higher blood levels have been correlated with increased risk of heart attacks. Iron surplus may aggravate hypersensitivity states. Storage of excess iron in body tissues is disease causing.
Iron Excess Iron has a negative side. Higher blood levels have been correlated with increased risk of heart attacks. Iron surplus may aggravate hypersensitivity states. Iron overload is less common than iron deficiency, but can result in serious disease, including cirrhosis, primary liver cancer, diabetes, cardiomyopathy and arthritis.
Fernández-Real et al provide convincing arguments that link iron and type 2
diabetes. They stated: “The relationship is bi-directional—iron affects glucose
metabolism, and glucose metabolism impinges on several iron metabolic pathways.
Oxidative stress and inflammatory cytokines influence these relationships,
amplifying and potentiating the initiated events. The impact of these
interactions depends on both the genetic predisposition and the time frame in
which this network of closely related signals acts. In recent years, increased
iron stores have been found to predict the development of type 2 diabetes while
iron depletion was protective. Iron-induced damage might also modulate the
development of chronic diabetes complications. Iron depletion has been
demonstrated to be beneficial in coronary artery responses, endothelial
dysfunction, insulin secretion, insulin action, and metabolic control in type 2
There are different opinions as to a desirable range of iron saturation. A middle range with a mean less than 40 % is probably healthier than higher levels. Iron saturation in a small group of female college students was less than 16%, considered to be too low, but all the subjects measured were physical fit, high performing athletes with no evidence of iron deficiency anemia.
Iron is often conjugated or chelated for supplement purposes; ferrous fumarate, and gluconate are commonly available. Ferrous sulphate is the cheapest iron supplement. Iron preparations tend to be constipating. Unabsorbed iron tends to darken stool color. Iron may be taken with vitamin C to enhance absorption, but copper intake may be impaired, and produce the same iron-deficiency effect. Iron supplements in the range of 10-30 mg per day may be desirable for some children, adolescents and women of child-bearing age.
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