Iron: the mineral essential for existence of life
Apart from being the most abundant metal on the planet, iron is iron is also the most essential substance to practically every life form in existence. Iron is a key player in the synthesis of proteins and enzymes involved in oxygen transportation as well as cell growth and differentiation. In fact, over 65 percent of iron is found in hemoglobin, the protein in blood that is responsible for carrying oxygen to the red blood cells. Myoglobin, a protein involved in the carrying the oxygen supply to the muscles, also contains smaller amounts of iron as do enzymes necessary for biochemical reactions.
Forms of dietary Iron
Dietary iron is found in two forms, namely heme and nonheme. Heme as its name suggests, is derived form hemoglobin, a protein in red blood cells responsible for carrying oxygen to other cells. This type of iron is found in animal sources that contained hemoglobin at one time, such as liver and other organ meats, lean red meats, fish and poultry and shellfish, especially oysters. Nonheme is the form found in plant foods such as lentils and beans, rice, maize, nuts, seeds, dark molasses, soybean and wheat and is also the chemical formation added to fortified foods. Animal sources of iron are much better absorbed than plant sources.
Iron levels are a tricky balance according to researchers. Too little iron can result in anemia, a condition in which there is not enough hemoglobin in the blood to carry oxygen to the cells and tissues, resulting in fatigue, weakness, constipation, loss of appetite, weight loss, and weakened immunity. Too much iron on the other hand, is not only toxic in many cases, but also fatal.
Absorption of Iron
For the most part, healthy adults absorb up to 15 percent of their iron stores from food. These storage levels also greatly influence the amount of iron the body will ultimately absorb. For example, when iron levels are already high, absorption levels will decrease, naturally protecting the body from any potential toxic effects. As well, iron absorption is significantly affected by the type of iron ingested. Iron from animal sources is the easiest to absorb, accounting for up to 35 percent of iron, while with plant sources it is normally absorbed only up to 20 percent.
Studies show that meat proteins and vitamin C will increase the absorption of plant sources of iron, therefore a meal that consists of meat and vegetables also rich in vitamin C, will ultimately increase the availability of iron in those vegetables.
Further studies show that tannins, a substance found in tea, polophenols and phytates, found in most legumes and grains, as well as calcium, all decrease the absorption of iron. In situations of pregnancy and high menstrual bleeding where iron requirements are very high, it is important to consider the foods that enhance iron absorption.
According to many studies including the National Health and Nutrition Examination Survey (NHANES) iron intakes for young females and children are at the greatest risk of an iron deficiency. This report also showed that 20 percent of adults age 20 to 59 and 13.6 of adult males 60 and older who did not have easy access to available food sources of iron, consumed less than half of the recommended daily allowance (RDA) of iron. In comparison, 13 percent of adults age 20 to 50 and 2,5 percent of adults age 60 and older from families who had sufficient food sources.1
Interestingly, a further survey showed that the type of foods being consumed greatly affect the overall ability of the body to effectively absorb iron. For instance, one study of 5,000 children and teens between the age of 8 and18 showed that close to 30 percent of their caloric intake was derived from low-nutrient density foods (high in calories but low in vitamins and nutrients) such as sodas sweetened with sugar, potato chips and most desserts, while 25 percent of these calories were from sugar foods. It was concluded that these children are at a significantly higher risk of developing an iron deficiency compared to those children who eat a balanced diet containing the recommended RDA of iron.2
Iron deficiency & Anemia
In an alarming report put out by the World Health Organization (WHO) as much as 80 percent of the world’s population may be iron deficient, while 30 percent is already suffering from anemia associated with iron deficiency.3
Iron deficiency in pregnant women is especially concerning since this condition is associated with greater risk of death to both the mother and baby as well as premature births, and babies with low birth weights. During pregnancy a woman’s iron requirement doubles, accounting for increased blood volume needs of mother and growing baby as well as the blood loss that occurs during delivery. Nutritionists estimate that today over half of all pregnant women in the world are iron deficient. According to the Center for Disease Control (CDC), in the US alone, one survey showed that 12 percent of women age 12 to 49 are iron deficient.4
Lower levels of iron decrease the risk of hearth disease
Studies of the effects of iron on such conditions as heart disease, show that lowered levels of this blood metal actually decrease the risk of coronary episode. It was concluded that iron may contribute to the oxidation of LDL (bad) cholesterol, synthesizing it into a form that is very damaging to the coronary arteries, thereby increasing the risk of heart attack and stroke.
An earlier study conducted in the1980s suggested then that lowered iron levels may reduce the risk of coronary disease. Regular blood loss, hence iron loss, associated with menstruation, opposed to the effects of estrogen, was reported as the cause in lowered incidence of heart disease in pre-menopausal women.5 Interestingly, further studies back this finding by reporting that individuals who frequently donated 1unit of blood each year for 12 years, were less likely to have cardiac episodes compared to those who only donated once during that time.6
Low levels of iron are associated with a diminished capacity for exercise tolerance. It is shown in one study that iron supplements improved exercise endurance during aerobic activities.
In a preliminary study cough associated with ACE (angiotensin-converting enzyme) inhibitors used to treat high blood pressure, was calmed and even prevented in some cases with iron supplementation. This common medication often produces a dry cough, a bothersome side effect causing many people to stop treatment.
Iron supplements can also be taken for hair loss. A comprehensive test showing low levels of serum iron, serum ferritin, and total iron binding capacity cab also be suspected as possible causes of hair loss. Hair loss restoration in such cases is possible with the use of iron supplements.
Iron supplements are available as ferrous sulfate, ferrous fumarate, ferrous succinate, ferrous gluconate, ferrous lactate, ferrous glutamate and ferrous glycine. Ferrous sulfate is the most common form found in supplements. The recommended daily dose of iron is 8 mg for males 19 and over and 18 mg per day for females between 19 and 50. Research shows that iron absorption decreases with increased dosing, therefore it is best to take prescribed amounts in two or three equally spaced doses.
Side effects of excess iron supplements
Most commonly, iron can cause upset stomach, nausea, diarrhea, heartburn and constipation. Some studies also suggest that high concentrations of iron stores can lead to cancer and Alzheimer’s disease. An iron overload can be very dangerous, especially to young children who have died after ingesting a single dose of 200 mg.
Iron can accumulate in the body tissues and organs when normal storage areas become full. As well, very little iron is excreted from the body in urine for example. Hemochromatosis, an inherited condition that results from excess iron accumulations over a period of time, can lead to skin discoloration, liver damage and even diabetes. According to the FDA, 45 mg of iron daily is safe. Severe iron overdose occurs in cases where 50 to 100 times the recommended daily does is taken. These amounts can result in death.
Like many other supplements, iron interacts with some drugs including those used to treat ulcers and other stomach problems such as cimetidine and ranitidine. These medications are known to change pH levels in the stomach, negatively affecting iron absorption. Iron levels are also lowered by birth control medications, In any case, if you are taking any kind of medication it is always best to speak with a health professional prior to taking supplements and herbs.
- Interagency Board for Nutrition Monitoring and Related Research. Third Report on Nutrition Monitoring in the United States. Washington, DC: U.S. Government Printing Office, J Nutr, 1996;126:iii-x: 1907S-36S.
- Kant A, “Reported consumption of low-nutrient-density foods by American children and adolescents”, Arch Pediatr Aolesc Med, 1993;157:789-96
- Stoltzfus RJ, “Defining iron-deficiency anemia in public health terms: reexamining the nature and magnitude of the public health problem”, J Nutr, 2001;131:565S-7S.
- Cogswell ME, Kettel-Khan L, Ramakrishnan U, “Iron supplement use among women in the United States: science, policy and practice”, J Nutr, 2003:133:1974S-7S.
- Sullivan JL, “Iron versus cholesterol—perspectives on the iron and heart disease debate”, J Clin Epidemiol, 1996;49:1345-52. [PubMed abstract]
- Meyers DG, Jensen KC, Menitove JE, “A historical cohort study of the effect of lowering body iron through blood donation on incident cardiac events”, Transfusion, 2002;42:1135-9.