How to increase your iron levels through food
Low iron is something I see regularly in clinic and I have experienced anaemia myself too.
When I was pregnant with my twins, I had been vegetarian for several years. I suddenly started craving spaghetti bolognese and not long after, my doctor told me I was anaemic. I think my cravings were telling me that I needed iron! Pregnancy is often a time when women develop iron deficiency, especially vegetarians and those carrying multiple babies ;)
Iron performs many important functions in the body, including transporting oxygen to our tissues (via haemoglobin), producing and releasing energy, and maintaining a healthy immune system.
There are two types of iron - haem iron and non-haem iron. Haem iron is found in animal products and is the most well-absorbed form, with our body absorbing up to 30% of the haem iron we consume. Non-haem iron is found in plant foods and is not as well-absorbed, with an absorption rate between 2 and 10%.
Sources of haem iron
Beef or chicken liver
Red meat
Oysters and mussels
Poultry (choose the dark meat)
Canned sardines or tuna
Eggs
Sources of non-haem iron
Whole grains, e.g. oats, quinoa, spelt
Enriched grains
Dark green vegetables, e.g. spinach, kale
Nuts, e.g pistachios, cashews, almonds
Beans, e.g kidney beans, black beans
Chickpeas
Seeds, e.g. sunflower, chia, pumpkin
Spirulina
Dulse (seaweed)
Dried apricots and raisins
Tofu
Increasing your iron intake through diet can be a bit tricky and there are a few important things to remember, particularly if you follow a vegan or vegetarian diet:
Avoid consuming dairy at the same time as iron-rich foods as calcium competes with iron for absorption in the body and this means less iron will be absorbed from your food. This applies to both haem and non-haem iron.
For toddlers and children with low iron, avoid serving milk with meals in order to maximise iron absorption.
Eat iron-rich foods at the same time as a source of vitamin C to increase the amount of iron that will be absorbed. Sources of vitamin C include citrus fruits, strawberries, tomatoes, capsicums, broccoli.
Some compounds in plants can block or slow the absorption of non-haem iron from foods. These include:
- Polyphenols, e.g. black and green tea, coffee (including decaffeinated) and dark chocolate.
These compounds can block iron absorption by up to 90% so my advice would be to not drink tea or coffee with meals and to save your dark chocolate until at least an hour after eating iron-rich foods.
- Phytates (e.g. beans, wholegrains, nuts, seeds, soy milk and tofu) and oxalates (e.g. raw spinach, almonds, dark chocolate and buckwheat)
The phytate content of foods can be reduced by fermenting, soaking or sprouting (e.g. nuts, seeds and grains) and the oxalate content can be reduced by cooking, e.g. cooked spinach has less oxalates than raw spinach.
I realise this may all seem a bit confusing and contradictory, particularly as many of the foods that are high in iron also contain iron-inhibiting compounds, e.g. spinach, dark chocolate and whole grains.
The best way to get around this problem is to not over-consume foods containing polyphenols, phytates or oxalates and to consume them away from iron-containing meals.
A quick word on supplements:
If you have a diagnosed iron deficiency, it is likely that you will need an iron supplement. Not all iron supplements are created equal and some of the products commonly recommended by doctors are known to cause gut issues. I recommend avoiding ferrous sulfate if you are prone to constipation. For children, liquid iron supplements like Spatone are usually well tolerated and you can increase their effectiveness by serving them with a small amount of orange juice.
References
American Red Cross Blood Services, 2023, ‘Iron rich foods’, The American National Red Cross, USA, viewed 14 March 2023, https://www.redcrossblood.org/donate-blood/blood-donation-process/before-during-after/iron-blood-donation/iron-rich-foods.html
Healthy Connections, 2023, ‘Iron absorption part two: foods that inhibit absorption’, Healthy Connections, USA, viewed 14 March 2023, https://www.healthyconnectionshr.com/blog/iron-part-two
Mascitelli L & Goldstein MR, 2011, ‘Inhibition of iron absorption by polyphenols as an anti-cancer mechanism’, QJM, vol 104 no 5, pp. 459 - 461.
Piskin E et al, 2022, ‘Iron absorption: factors, limitations, and improvement methods’, ACS Omega, vol 7 no 24, pp. 20441 - 20456.
Roughead ZK, Zito CA & Hunt JR, 2005, ‘Inhibitory effects of dietary calcium on the initial uptake and subsequent retention of heme and nonheme iron in humans: comparisons using an intestinal lavage method’, The American Journal of Clinical Nutrition, vol 82 no 3, pp. 589 - 597.
Tolkien Z et al, 2015, ‘Ferrous sulfate supplementation causes significant gastrointestinal side-effects in adults: a systematic review and meta-analysis’, PLoS One, vol 10 no 2.
Young I et al, 2018, ‘Association between haem and non-haem iron intake and serum ferritin in healthy young women’, Nutrients, vol 10 no 1.