Plant sources of iron

Posted on 30th December 2016

World Health Organisation (WHO) states that approximately 2 billion of the World’s population (30%) have iron deficiency anaemia (1). Some these cases are due to impaired absorption, but the major part is related to malnutrition and undernutrition. (Malnourished should not be confounded with undernourished. The former means that the individual’s diet is lacking certain macro- and/or micronutrients, the latter – that the individual is consistently not eating enough.)
 
There have been some concerns expressed recently by diverse public health experts (and “experts” as well) about the prevalence of iron deficiency anaemia in teenage (aged 12-18) girls and some of those proclaiming these concerns put an emphasis on the increasing “trend” in becoming vegetarians or vegans.
 
Let us have a look.
100 g of braised beef contain 2.7 mg of iron;
100 g of cooked lamb – 1.1 mg;
100 g of roasted turkey – 1.2 mg;
100 g of boiled red kidney beans – 2.5 mg;
100 g of boiled red split lentils – 2.4 mg;
100 g of boiled soya beans – 3.0 mg;
100 g of cashew nuts – 6.2 mg;
100 g of tahini (hulled sesame seed) paste – 10.6 mg;
100 g of pumpkin seeds – 10.0 mg (2)
 
Recommended daily allowance for iron for girls aged 9-13 is 8 mg/day; for girls aged 14-18 – 15 mg/day; for pre-menopausal women – 18 mg/day; men and post-menopausal women – 8 mg/day (3).
Adjusting the portion size – for example, one portion of beef is 70 g, whereas one portion of cooked lentils is 70-100 g, nuts or seeds – 30-50 g (4) and considering that one should consume twice as much iron from plant sources (“non-heme”, as opposed to “heme” iron from animal sources) because of lower bioavailability (3), it is rather clear that one can get more than sufficient quantity of daily iron exclusively from plant-based sources. If we increase the absorption of the mineral combining iron-rich foods with foods containing vitamin C, such as citrus fruits, bell peppers, tomatoes, kale, rocket and similar, the whole task of reaching the recommended daily intake gets even easier. 
 
On the other hand, consuming dairy products together with iron-rich foods decreases iron absorption because of the calcium contained in dairy. Drinking tea or coffee during meals has the same effect. Tea, both black and green, and coffee contain tannins, substances that bind to iron molecules and prevent their absorption and assimilation by the body (3).
 
Bottom line: provided there are no underlying health conditions influencing iron absorption and following the above mentioned advice: a) eating 2x more iron from plant sources than would be recommended for iron from animal sources; b) combining iron-rich foods with vitamin C-rich foods; c) avoiding absorption-impairing combinations one can get as much iron as one’s body requires purely from plant sources.
 
1.        WHO. WHO | Micronutrient deficiencies. WHO. World Health Organization; 2015.
2.        Finglas P, Roe M, Pinchen H, Berry R, Church S, Dodhia S, et al. McChance and Widdowson’s The Composition of Foods. Cambridge, UK; 2015. 630 p.
3.        NIH. Iron, Dietary Supplement Fact Sheet. NIH Health Information. 2016.
4.        BUPA. Portion size [Internet]. 2016 [cited 2016 Dec 28]. Available from: https://www.bupa.co.uk/health-information/Directory/P/portion-size
 
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