Unfortunately, despite many plant sources of iron being very iron rich, the absorption of iron from animal sources (heme iron) and from plant sources (non-heme iron) is not the same. Heme iron is absorbed more uniformly than non-heme iron with 15% to 35% of that which is eaten being absorbed. The absorption of non-heme iron depends on the balance between factors in our food that inhibit or enhance iron absorption. In meat eaters it is estimated that heme iron makes up 10% to 15% of the iron that we eat, but it contributes more than 40% of the total iron that is absorbed. When trying to improve your iron levels it is imperative that you eat foods that are rich in iron in combination with those that are high in enhancers and low in inhibitors of iron absorption. When examining diets and the foods that are consumed most regularly, and in combination, it starts to become clear why iron deficiency is so prevalent. Inhibitors of iron absorption The factors in our foods that inhibit iron absorption are calcium, certain proteins, phytates and polyphenols. Calcium is the only inhibitor that reduces absorption of both heme and non-heme iron, while the other inhibitors only affect non-heme iron. CALCIUM If calcium-rich foods are ingested at the same time as iron, then calcium can prevent the absorption of iron. The inhibitory effect is from 165 milligrams calcium and higher. A cup of milk contains approximately 300 milligrams of calcium. Milk, cheese and yoghurt (but not cream or butter) are particularly high in calcium. PROTEINS In addition to the effect on iron absorption caused by calcium in milk, the two milk proteins - casein (used to make cheese) and whey - as well as the proteins in egg whites and soya beans all decrease iron absorption. PHYTIC ACID Phytic acids are the phosphorus storage unit found in many plants, particularly grains, nuts and seeds. This anti-nutrient inhibits the absorption of the important minerals calcium, magnesium, zinc and iron. If the molar ratio of phytate to iron is more than 1:1 then iron absorption will be reduced. For example, the molar mass ratio of phytate to iron in cocoa is approximately 10:1, so unless one reduces the phytate content in cocoa, one isn’t absorbing this excellent source of iron. Methods of reducing phytic acids in foods are cooking or roasting (so choosing cocoa rather than cacao), sourdough fermentation rather than yeast fermentation of breads and soaking and then toasting or dehydrating (activating) seeds and nuts. 44 Pindara Magazine 2016
Pindara Private Hospital Magazine - Issue Eight
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