Commentary [Volume 7 No. 5 (2007)]

Dr. Michael Lokuruka

Michael N. I. Lokuruka

Lecturer, Department of Dairy, Food Science and Technology Egerton University,
P.O. Box 536, Egerton, Kenya. E-mail:

The most prevalent micronutrient deficiency in the world is lack of iron [1]. Iron is an essential mineral and an important component of proteins involved in oxygen transport and metabolism, and is also an essential cofactor in the synthesis of neurotransmitters such as dopamine, norepinephrine, and serotonin. Meats, cereals, legumes and vegetables are major dietary sources of iron [2]. Their relative contribution depends on the amounts consumed and other variables discussed herein. When cereals flours are consumed in large quantities as for Ugali in agrarian communities in Kenya, because they are cheaper staples than meats, they are likely to make a greater contribution than the better iron sources, meats and liver. In Sub-Saharan Africa, pastoralist nomads are more efficient in the use of a slaughtered animal than the agrarian communities. The livestock-keeping Turkana of Kenya use animal blood to raise the iron in “eengol,” the pulp of the fruit of the Turkana doum palm, Hyphaene coriacea. In doing so, protein, the essential amino acids and other minerals are increased in the composite meal unintentionally; similar to the Maasai of Kenya and the Karimojong of Uganda, they also drink fresh animal blood sometimes alone, or mixed with milk, ghee or sugar, with good nutritional results. Despite the body utilizing absorbed iron efficiently, only a small portion of the iron present in the diet is absorbed. Adults absorb only about 15% of dietary iron, although individuals who have a special need for iron, such as growing children or pregnant and lactating women, are able to absorb more [3].

Meat, blood, or offal contain organically-bound haeme iron that is easier absorbed in comparison to the nonhaeme iron in plant foods. Therefore, little of the iron added to fortify cereal flours is absorbed. Similarly, only 2-3% of the nonhaeme iron in vegetables is absorbed [3]. Encouraging greater consumption of meat and vegetables/fruits due to the vitamin C content in the latter is prudent, and if consumed with other foods fortified with such iron-rich ingredients as animal blood, better iron status may be attained. Vitamin C in the diet promotes absorption of non-haeme iron because it reduces ferric iron to the absorbable ferrous state and helps to keep it as ferrous iron. Moderate alcohol use also promotes absorption of non-haeme iron, although its excessive consumption may lead to degenerative diseases and malnutrition, while tea, probably the most consumed nonalcoholic beverage in Kenya, and, coffee, which form insoluble tannic acid salts with iron, have the opposite effect.

The RNI (recommended nutrient intake) for iron is based on an assumed rate of 15%, and the amounts needed for growth and accumulation of an iron store are 11.3 mg and 14.3-14.8 mg/day for adult males and females, respectively [3, 4]. Women with high menstrual losses may require more, and this may usually be achieved by taking iron supplements. The increased need of pregnancy and lactation can normally be satisfied from the body’s iron stores in the absence of losses through menstruation, and as long as intake of food of adequate iron content is assured. Dietary iron supplementation is usually then only required where maternal stores are low at the start of pregnancy. Prolonged shortage can deplete iron stores such that the amount of haemoglobin in the blood will fall below normal levels precipitating iron deficiency anaemia.

Despite the need for supplementation or food fortification to meet metabolic needs of iron in deficiencies, iron is a prooxidant that helps generate free radicals, the reactive charged ions that cause damage to cells in the human body. Hidehiro Matsuoka, a Japanese researcher and his team fed ten healthy male volunteers an iron overload which led to an increase of malondialdehyde, a marker of oxidation and of impaired endothelial function. They observed destruction of the endothelium, the thin lining of arterial walls, which is linked with heart and arterial disease [5] . Use of a drug to lower iron levels in the ten healthy male smokers, lowered levels of the chemical and made the endothelium work better. The study showed the need to recognize iron as a risk factor for atherosclerosis and understand the need to control body iron levels to prevent cardiovascular disease (CVD). Men would be more prone to iron overload and associated risks than pre-menopausal women. Moreover, in a major study with 35,000 postmenopausal women, study results suggested that a high intake of haeme iron might be harmful, whereas a high intake of zinc might be beneficial in relation to CVD mortality in the presence of a trigger that can disturb iron homeostasis, such as alcohol consumption [6]. Epidemiological studies also support the notion that consumption of animal protein (except fish) is positively correlated, while vegetable protein is negatively correlated with CVD mortality rates [7]. Strict vegans would, however, be more vulnerable to iron deficiencies than lacto-ovo-vegetarians and nonvegetarians.

The U.S. National Institutes of Health considers taking up to 45 mg of iron per day as safe for the general adult population [8]. However, if one has heart disease or is at particular risk for it (for example, being a man over age 45, a woman who has gone through menopause, or one with high serum cholesterol, diabetes, or high blood pressure) and is taking a multivitamin, it is best to make sure that there is no more than nine milligrams of iron per daily dose of the vitamin [8]. Caution is therefore called for when fortifying foods with iron so as to minimize risks with iron levels beyond metabolic and storage requirements, and considered in the context of bioavailability and toxicity, as every action has its downside, as in the law of physics-“for every action, there is an equal and opposite reaction.” While supplementation may be needed in early pregnancy in case of low maternal iron stores and in females with high menstrual losses, malaria, amoebiosis, helminthic parasitic infections and vitamin A deficiency, aggravated by poverty and poor hygiene, can also precipitate iron deficiency anaemia, necessitating remediation.


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