Key Topics Covered
- According to some data from The Lancet, Iron Deficiency Anaemia effects more than 15% of the world’s population.
- This data is obviously skewed by a few factors such as age, gender, socioeconomic status, activity levels etc.
Quantifying Iron Needs
- RDI for men/non-menstruating people is 8mg
- For women aged 18-50 (people who menstruate) it is 18mg
- For Pregnant people it is 27mg
- For vegans and vegetarians, requirements are 1.8x the RDI due to difference in absorption rates from plant versus animal proteins
Other Factors That Could Make Your Needs Different
- The aged 18-50 RDI of 18mg assumes menstruation. Without that, it would be lower.
- The RDI assumes a combined intake of haem and non-haem iron.
- Exercise such as running can increase needs
- Potentially your absorption is lower
The RDI is gread for adding context, since otherwise the iron amounts in food doesn’t really make sense in isolation. But using some common sense, your own personal needs won’t be exactly these numbers.
Adding Context around Iron Rich Foods
- 100g of red meat is 2.5mg of iron. Add this into the context of aiming for 18mg+. Even 200g is still only 5mg.
- Other meats and fish still contain iron, albeit less than red meat e.g. 100g of chicken breast contains 1mg of iron
- 100g of spinach is 2.7mg of iron (but spinach is also really high in oxalates which inhibits iron absorption significantly, 100g of spinach is also quite a large serving size)
- 100g of cooked lentils is ~3.3mg of iron – absorption is better than from spinach BUT it is still non-haem iron
- Liver and other organ meats are often super high in iron – 100g = 6.5mg of iron
As you can tell from this, getting to a target like 18mg is pretty hard, even under good circumstances.
And then for vegans and vegetarians the requirements can be as high as 32mg/day!
- Adding a calorie deficit into this makes it even harder
- For example, it is much easier for a male maintaining on 3000kcal to meet his iron requirements vs a female trying to lose weight on 1500kcal and meeting hers. Therefore, lower calorie targets, particularly for females makes it hard to get 18mg/day.
Haem Iron vs non-Haem Iron
- Haem iron is found in animal foods and non-haem iron is mostly found in plant based foods
- Haem iron is very bioavailable and the absorption rate is really good
- On the other hand, the absorption of non-haem iron can be significantly reduced by many things including calcium, phytates & oxalates (found in fruit, veg, grains, seeds, nuts, legumes etc), tannins (in tea and coffee) and zinc
- So if you are getting most of your iron from plant based sources, you will need a higher intake of iron overall (maybe up to twice the amount of the RDI)
- But you can also do things to increase absorption
- Take calcium and zinc supplements away from iron rich foods
- Pair sources of iron with sources of vitamin C (fruit & veg)
- Soak and sprout legumes & grains
- Keep tea and coffee away from meals
- Although I am a proponent of a food first philosophy, I am usually pretty quick to recommend either supplements or an iron infusion.
Taking an iron supplement every second day instead of every day has been shown to help with increasing absorption of that iron and may be worth considering
Relevant Links / Resources