Expert Nutrition

Learn about Iron and why you should be cautious of iron supplements

Iron plays an important physiological role in the body in particular in the making of haem where most the body’s iron is found. Haem is the active molecule that makes up haemoglobin and myoglobin which are used in the transport and delivery of oxygen to body tissues. Iron is also found in the liver where a large portion of iron is stored in the form of ferritin and haemosiderin.

Haemoglobin, which is found in red blood cells makes up about two thirds of the body’s iron content and has an essential role in the uptake of oxygen from the lungs and actively delivering it to the metabolising tissues. Myoglobin is found in muscle tissue and acts as an oxygen reserve that is released during periods of peak metabolic activity such as intense exercise.

As the body breakdowns down old red blood cells it recycles most of the iron however in adults approx. 1mg of iron is lost a day through the loss of skin cells and cells that line the bowel increasing to 1.5mg in women up until menopause through blood loss in menstruation. Given the iron content of the body is highly conserved, the body does not need to absorb much iron to achieve iron balance.

Despite the fact that the body requires little iron to maintain iron balance only about 10-20 % of dietary iron is absorbed. This can however be influenced by a number of factors such as need, the dietary form of iron ingested (haem vs non –haem) and the presence of other nutrients that can either promote or inhibit iron absorption. Most governing health bodies set a daily recommendation of up to 10 times what the body needs (assuming as little as 10% absorption) to ensure that people obtain their daily requirements.

Inadequate iron consumption can lead to varying degrees of deficiency including iron-deficient anamia which is the most common nutritional deficiency in developed countries. Iron deficiencies are most common in menstruating or pregnant women, pre-school children, vegetarians, some athletes and people on very restrictive diets.

Although the best known dietary sources of iron include red meats, about 40% of the iron in the Australian and New Zealand diets actually comes from the consumption of wholegrain cereals. Good sources of iron include red meats (particularly liver), wholegrain cereals, fish, poultry, fruits and vegetables. Iron found in meat (haem) is more easily absorbed than that found in plant products (non-haem) as it has a greater bioavailability, however Vitamin C and other organic acids such as citric, lactic, or malic acid have been proven to increase the absorption of both forms of iron.

Unlike other mineral elements there is no physiological mechanism for the excretion of iron and therefore it is easy for iron levels to accumulate to toxicity. Iron overload can cause the deterioration of lining of the gut, vomiting and diarrhea, abdominal and joint pain, liver damage, loss of weight, intense fatigue and acute doses as low as 3 grams can cause death in children.

Haemochromatosis is a hereditary disorder that leads to excessive absorption of iron, which then accumulates within the body to toxic levels that can potentially be fatal. It affects approx. 1 in 300 Australians and 1 in 250 Americans. Iron toxicity can have a negative impact on all bodily organs in particular the heart, brain, liver, pancreas and lungs, and can lead to the development of diseases such as diabetes, liver cirrhosis and cancer. Symptoms usually appear gradually and it is not uncommon for them not to be identified until middle aged. Haemochromatosis can be diagnosed with blood tests and despite the potential dangerous condition, if detected early enough it can be managed such that can you live a long healthy life.

Beware of Iron Toxicity Caused by Supplements

Many people, unaware of the dark side of iron, consume iron supplements overloading their system and actually increasing the risk of oxidative stress. Others take iron containing multi-vitamins faithfully, believing that they are doing themselves good. The problem here is that other nutrients, such citric acid and Vitamin C, commonly found in most multivitamin formula’s are powerful iron absorbing agents and can unintentionally cause iron overload increasing the risk of heart disease, cancer, osteoporosis, and arthritis – which is not really the desired outcome of a supplement. On the other hand vitamin E, magnesium, copper and particularly calcium can all inhibit iron absorption and therefore it is hard to determine what, if any, or too much iron will be absorbed from the multivitamin.

Unless you are a women with a regular menstrual cycle, the only way to remove excess iron is through bleeding. That is why for men, iron overload can be quite problematic to resolve.

In summary some nutrients compete with iron for absorption and some enhance it, which presents numerous dilemmas if professionals are trying to correct an iron deficiency through supplementation. It is for this reason that supplemental iron should not be taken in combination with other supplements. If you are required to supplement with iron we recommend you do so with an “iron supplement” (possibly with added vitamin c to aid absorption) and not a generic multivitamin, such that the iron absorption can be controlled to achieve the desire result. Additionally given the implications of iron toxicity, the supplementation of iron through nutritional supplements should be done with extreme caution and only when recommended by your doctor.

To be on the safe side if you need to increase your intake of iron, it is strongly recommended that you do so through your diet and not through nutritional supplements. Lean red meat, dark green leafy vegetables, dried beans and wholegrain cereals are the safest sources of iron. Iron consumed through lean meats and other natural food sources will not generally lead to iron overload in healthy people.

1. National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand. Department of Health and Ageing; 2006 pp187-191.
2. Wahlqvist, M.L., et al. Australia and New Zealand: Food and Nutrition. 2nd Ed. Allen and Unwin, Sydney; 2002, pp275-276
3. Stanton R. Foods that harm, foods that heal: An A-Z guide to safe and healthy eating. Readers Digest; 2006, pp 256-261.
4. MacWilliam, L.D. Comparative Guide to Nutritional Supplements. Northern Dimensions Publishing; 2005 pp59-62.
5. The Merck Manual of Medical Information 2nd Ed. Beers, M.H., Fletcher, A. J., Jones T. J., Porter, R., Berkwits, M., et al., editors. Pocket Books Reference; 2003 pp825.

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