I only became aware that certain food and drinks aid or block absorption of nutrients, when I started my nutrition masters. I thought if I didn’t know, then other people might not, so I thought it was important to write a blog post about it. In this post I will tell you about some of the food and drinks that are known blockers and aids for absorption of iron. Before I do this, I feel like I should explain what I mean by absorption in a nutrition context. Absorption relates to how much nutrients in a food is absorbed by the body, so if you ate a food high in vitamin A, how much of that vitamin A can your body absorb from eating that food.
Back to iron. We obtain iron from various food sources, such as red meat, pulses (beans and lentils) and leafy greens (broccoli and spinach). Red meat and other animal sources of iron are what is known as haem iron and plant-based sources of iron are known as non-haem iron. Haem iron has a high potential for iron absorption (Hallberg et al. 1979), but to increase iron absorption further it’s best to pair haem iron with non-haem iron, so basically steak and some broccoli is the perfect combo!
Certain things can enhance iron absorption of high iron foods. Orange Juice! I don’t actually like orange juice, which is not great for someone who is iron deficient, as orange juice has been found to increase iron absorption (Callender et al. 1970). So, if you do like orange juice then it is the perfect drink to take with iron supplements or a high iron food. So get drinking that vitamin C!
As I said, I myself have an iron deficiency and always felt very lethargic, despite taking prescribed iron supplements. It wasn’t till a small comment was made in one of my lectures that I understood why. I learnt that certain foods that I ate, may block iron absorption from both foods and iron supplements. So what foods and drinks have this affect you may ask? Well you are about to find out.
Tannins have been found to affect iron absorption in various studies (Afsana et al. 2004). Tannins are found in hot drinks such as tea, coffee and green tea and these give these drinks their colour, hence an English tea will have more tannins than a green tea. This isn’t to say you can’t have tea or coffee anymore, how would English people survive? No, this is just to say that if you have low iron then you may need to think about lessening your intake of teas and coffees and not have them close to meal times. This knowledge has changed my energy levels for the better. I used to have a coffee and a green tea a day and since learning this I have changed to having one drink containing tannins each day. Since this I have really noticed that I have less anaemic symptoms. Whether this is from lessening my tea and coffee intake, I cannot be certain but I thought I’d share what seems to have worked for me. For people that do not have a deficiency then these tannins should have little effect on you but it’s still worth keeping this in mind.
Tannins can also be found in wines and other foods, such as berries, so it isn’t just hot drinks the average person with anaemia should be aware of. People often enjoy a glass of wine with dinner, but is this the best thing if wine affects the amount of iron we can absorb from our food? Perhaps not.
There are also foods that can block iron, such as eggs (Morris & Greene 1972). This isn’t to say don’t eat eggs because they do offer many benefits, but if you do take iron tablets then its best to have a few hours break between eating the egg and consuming your iron tablets. Similarly, it appears that if you consume eggs alongside other high iron ingredients, then this may reduce some of the iron absorption you get from these high iron foods. If you don’t have low iron then yolk away! Also, foods high in calcium can block iron so cheese on your beef burger may not be the best idea for those with iron deficiency.
This was a short whistle stop tour which looked into some of the many foods and drinks which have been linked with iron absorption, but of course there are always new pieces of evidence emerging. Ultimately the message here is carry on with your diet but if you feel that you experience anaemic symptoms or already know that you are anaemic, then it may be best to follow some small changes. If you happen try any of these changes because of the reasons we have discussed in this post, then please get in touch; I’d love to know how you get on!
Afsana, K., Shiga, K., Ishizuka, S. and Hara, H., 2004. Reducing effect of ingesting tannic acid on the absorption of iron, but not of zinc, copper and manganese by rats. Bioscience, biotechnology, and biochemistry, 68(3), pp.584-592.
Callender, S.T., Marney Jr, S.R. and Warner, G.T., 1970. Eggs and iron absorption. British Journal of Haematology, 19(6), pp.657-666.
Hallberg, L., Björn-Rasmussen, E., Howard, L. and Rossander, L., 1979. Dietary heme iron absorption: a discussion of possible mechanisms for the absorption-promoting effect of meat and for the regulation of iron absorption. Scandinavian journal of gastroenterology, 14(7), pp.769-779.
Morris, E.R. and Greene, F.E., 1972. Utilization of the iron of egg yolk for hemoglobin formation by the growing rat. The Journal of Nutrition, 102(7), pp.901-908.