This is part 1 in the 2-part series regarding Iron absorption.
Did you know that the recommended daily requirement of Iron is 8 mg for adults? For adult women under 50, the daily requirement is more than double at 18 mg (to make up for blood losses associated with the menstrual cycle).
First of all- even the 18mg requirement seems like a low number. You must be thinking is it so hard to get even that much iron in our body? Secondly, you will see soon that quite a bit of foods that we eat in India contains iron. Yet, over half the women in India are reported to be anemic. Why is that?
First question: Are you a vegetarian or meat eater? Cuz that makes a difference….
Heme Vs Non-heme Iron (a.k.a Meat vs Plant based iron)
There are 2 types of dietary iron: Heme iron (iron from meat and fish) and non-heme iron (iron in plant foods and some meat).
Iron absorption from foods is on average 18%, however heme iron is absorbed at a more efficient rate of 23% vs absorption of non-heme iron is variable between 2-20% depending on various factors.
So, if you are a vegetarian, you could be getting as low as only 2% of the iron in the foods. However, the more you understand the process of iron absorption, the more you can move that scale from 2% all the way to 20% from the exact same meal.
Plants are not just going to willing give away its minerals to us. It is tightly locked within the grains, seeds etc. So, we need to unlock the stored iron in plants and then – be able to absorb it into our body.
Unlocking the Iron
One of the main villains when it comes to releasing iron from foods is an anti-nutrient called Phytic acid. When phytic acid is bound to a mineral in the seed, it’s known as phytate. Phytate is one of the major inhibiting factor for zinc and iron absorption.
For e.g., a study found that Phytic acid is a potent inhibitor of iron absorption and low absorption of iron from cereal- and/or legume-based foods. This is a major factor in the etiology of iron deficiency in infants.
To unlock it, we need to reduce the phytic acid in the food via processing techniques like germination (sprouting) or fermentation. Roughly, germination reduces phytic acid by 45%, whereas fermentation can reduce phytates by about 77%.
So, germinate or ferment your grains!!
Factors (other than phytic acid) that help/hinder Iron Absorption
Plant: “I won’t give so easily up the iron I worked so hard to collect.”
Me: “Ok, fair enough.” Spends a day or 2 germinating/fermenting grains and legumes.
“Yay, iron unlocked, problem solved!!”
Body: “Not, so fast.”
Me: “what now??”
Body: “You just had chai with your meal. That tannin guy just stole the unlocked iron.”
This is obviously a super simplified version of what happens inside. But, there are other Inhibitors/Promoters in play when it comes to absorbing Iron. To absorb the iron, we need to eat our meals in a way that promotes iron absorption and avoid foods that hinder the process.
According to a paper published in the Journal of Nutrition and Metabolism, titled A Review of Nutrients and Compounds, Which Promote or Inhibit Intestinal Iron Absorption:
The most important promoters of iron absorption in foods are:
- Ascorbic acid (Vitamin C)
- Lactic acid (produced by fermentation),
- Meat factors in animal meat (the presence of heme iron)
- Alcohol which stimulate iron uptake by inhibition of hepcidin expression.
The most important inhibitors of iron uptake are:
- Phytic acid/phytates
- Proteins from soya beans, milk, eggs, and calcium.
The absorption of nonheme iron, is greatly influenced by meal composition. So, for vegetarians – having more acidity in the meal promotes iron absorption. Ascorbic acid (Vitamin C) is a powerful enhancer of nonheme iron absorption and can even reverse the inhibiting effect of such substances as tea and calcium/phosphate.
While this is great news, we still have to understand the factors that hinders Iron absorption.
Phytic acid hinders absorption, but we can bypass that factor by germinating or fermenting as discussed before. Having calcium rich foods and having tea/coffee with your meals hinders absorption.
In the following video, the nutritionist provides 5 ideas to help you absorb the iron from your meal, which I thought were really good ideas.
I feel Indians in particular really need to heed the advice on tea. We drink chai for absolute no reason at all. All the tannins in chai inhibit the absorption of the iron in the meal, especially if you are a vegetarian/vegan who eats plant sources of iron (non-heme iron). So, don’t drink chai during a meal. Do it a few hours after or before instead.
I hope this post helped in understanding all the factors that go into iron absorption in the body.
In conclusion, to increase Iron levels:
- Unlock Iron (reduce phytates):
- By germination of grains, legumes, nuts and seeds
- By fermentation of grains, legumes, vegetables
- Absorb Iron more:
- Plan meals with Vitamin C + Iron for better absorption
- Remove any form of coffee and tea from your meals
- Space out your Calcium rich foods from your Iron rich foods.
You must be wondering why is the body being so damn picky when it comes to Iron absorption. It is because Iron is a double edged sword where the body suffers if there is too less iron or too much iron. The Upper limit of Daily Iron intake is 45 mg.
I highly recommend the Youtube videos from Dr. Stefano Vendrame (Ph.D. Human Nutrition) for detailed information:
Iron deficiency is an extensive subject and this blog is just a starting point. But, the more you know, the better choices you can make in your diet.
Ok, Now that you understand the complexities of iron absorption, we can get into the values of iron in foods. Check out Part 2 in the series on Iron absorption here: “Which Indian Foods are rich in Iron?”