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Iron

World Iron Awareness week

Facilitated by Beef + Lamb New Zealand, the Iron Awareness Week campaign draws attention to the issue of iron deficiency. Beef + Lamb New Zealand is quick to claim the ‘superiority’ of haem iron sources, hoping to convince Kiwis to buy more of their products. What they fail to mention is that our per capita meat consumption is already one of the highest in the World. Beef & Lamb’s solution of pushing more of their saturated fat, cholesterol, and carcinogen-laden meat on us is only going to do more harm.

Iron deficiency is not necessarily the consequence of low intake but can also be the result of various medical conditions (from chronic renal failure to coeliac disease to gastrointestinal blood loss) and excess intake of zinc which hinders iron absorption). Iron-deficiency anaemia is a serious problem in the developing world due to a limited food supply, but in Western countries, it is most common in obese women who follow restricted calorie diets to lose weight.

There are two types of iron in food: haem and non-haem iron (aka heme and non-heme iron). In animal products, 40% of the total iron content is haem iron and 60% is non-haem iron. Haem iron has higher absorption rates (around 10-25%). Plant foods contain only non-haem iron and its absorption rate (can vary from 1% to 23%) will depend on the body’s need for iron (Collings et al, 2013). In other words, people with low iron stores will absorb more and excrete less non-haem iron.

Vegetarians who eat a varied and well-balanced diet are not at any greater risk of iron deficiency anaemia than non-vegetarians” - (Saunders, 2012).

Healthy iron sources: whole-grains, legumes, nuts, seeds (especially pumpkin seeds), dried fruits, iron-fortified cereals and green leafy vegetables. Read more about non-heame iron sources on our main iron page.

Iron Inhibitors & Enhancers

Consuming healthy iron-rich foods in combination with vitamin C-rich foods (such as citrus, broccoli, bell peppers etc.) in the same meal will improve iron absorption. The bio-accessibility of iron from whole-grains (such as brown rice, quinoa) can also be increased by garlic and onion. As little as one thin slice of onion can significantly increase iron absorption.

Drinking tea and coffee with meals can impair iron absorption so try to avoid those. Other than tannins in tea and coffee, there are many more iron inhibitors. But the good news is that vitamin C can overcome the effects of phytic acid, polyphenols, calcium and milk proteins. Luckily, vegetarian diets are high in vitamin C.

Some studies found that oxalic acid in spinach, silverbeet may inhibit iron absorption, however recent studies suggest that its effects are insignificant.

Too much of a good thing?

Both haem and non-haem iron are absorbed in the small intestine but via different mechanisms. Haem iron is absorbed through the gut wall intact, regardless of how much we need. Non-haem iron absorption is more carefully controlled, as it is more readily absorbed when the body is in need of iron. It is a smart protective measure for iron overload.
This is very important, as the body has limited mechanisms for excreting excess iron other than the shedding of skin, hair, and menstruation. Hence, iron stores can insidiously increase as we age.
Too much iron is just as bad as too little. High intakes of iron have been linked to an increased risk of colorectal cancer, heart disease, infection, neurodegenerative disorders, inflammatory conditions, Alzheimer’s, Parkinson’s, arthritis, and diabetes (Greger, 2012, 2017).

But somehow we doubt we’ll hear much about the other side of the iron issue during iron awareness week…

Sources

  1. Collings R, Harvey LJ, Hooper L, et al. (2013). The absorption of iron from whole diets: A systematic review. Am J Clin Nutr. 2013;98(1):65-81.
  2. Greger, M. (27/1/2017) Donating Blood to Prevent Cancer? Video File. Volume 34. Available at: nutritionfacts.org
  3. Greger, M. (25/7/2012) New Mineral Absorption Enhancers Found. Video File., Available at: nutritionfacts.org
  4. Greger, M. (27/7/2012) Risk Associated with Iron Supplements. Video File. Volume 9. Available at: nutritionfacts.org
  5. Saunders, A.V., Craig, W.J., Baines, S.K, and Posen J. S. (2012). Iron and vegetarian diets. MJA Open. doi:10.5694/mjao11.11494