Iron on a plant-based diet - what you need to know

Iron on a plant-based diet - what you need to know

Iron is one of those critical nutrients to look out for on a plant-based diet - find out what you need to prioritise to keep it in check


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Iron on a plant-based diet is an interesting topic, and those of a more meat-eating orientation tend to see iron as another struggle for those who eat plant-based. The reality is, is that with a little bit of knowledge, iron is easy to get more than enough of while eating a plant-based diet. The mechanisms of iron in the human body are extremely complex; in this post I’ll aim to outline what iron is and how much we need, the differences between the iron found in animal products and that only found in plants, and what you can do to maximise your iron intake on a plant-based diet.

What is iron and how much do we need on a daily basis?

Iron is a vital mineral for optimal human function, as it is responsible for making haemoglobin which transports oxygen in the blood. It is widely known to be the most common nutrient deficiency in the world - regardless of whether you are adopting a plant-based or animal-based diet. The symptoms of iron deficiency include fatigue, dizziness and shortness of breath.

Iron requirements differ depending on what stage of life you are at. Below is a table from the Association of UK Dieticians outlining the recommended daily allowance for each particular stage of life:

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As you can see, various stages of life require different amounts of iron. One thing you may notice is the overall higher iron requirements for females once they hit adolescence and adulthood, and the the principle reason for this is the process of menstruation. As well as losing some iron through stool and urine, females also lose a fair amount of iron during their monthly cycle - making their iron requirements during adolescence and adulthood greater than males.

Heme Iron and Non-Heme Iron

Dietary iron comes in two forms; heme-iron and non-heme iron. Animal products are composed of around 40% heme iron and 60% non-heme iron, and plant-foods are compiled of 100% non-heme iron.

Heme iron is widely known to be absorbed better by the human body, and this efficiency is is because heme iron absorption is largely uninfluenced by other dietary factors and components. It has around 15% - 35% bioavailability. Non-heme iron, on the other hand, is a different proposition. The absorption of non-heme iron is impacted by other dietary factors in plant foods including phytates, oxalates and nutrients such as calcium, and the percentage of absorption is around 2% - 20%

Despite heme iron's superior absorption, there are factors that you want to think about. As it is so readily available, it will continue to be absorbed when consumed, even if our iron levels are within the optimal range. The problem with this is that excess iron can contribute to metabolic illness. This was highlighted by a meta-analysis of 8 studies that showed that there is a positive link between heme-iron intake and an increased risk of colorectal cancer. This is due to something called endogenous n-nitrosation in the intestinal tract from consumption of heme iron - something which you can read about in more detail here.

The benefits of eating plant-based iron sources are also demonstrated by the fact that the fibre, fruit and vegetable content are obviously much higher than when eating heme iron found in muscle tissue. These are protective against the development of metabolic syndromes such as high cholesterol, elevated blood sugar and high blood pressure - which increase the chances of chronic diseases such as cardiovascular disease and Type 2 diabetes.

Many plant foods are rich in iron - and whilst absorption can be an issue in some cases, there are ways to get successfully optimise it
Many plant foods are rich in iron - and whilst absorption can be an issue in some cases, there are ways to get successfully optimise it

Plant-based sources of iron - and how to optimise absorption

So which plant-foods are rich in iron? We're talking lentils, chickpeas, soy products such as soybeans, tofu and tempeh, sesame seeds, dark leafy greens, oatmeal, pinto beans and dried fruit such as apricots to name a few. Get plenty of these into your rotation to get the most bang for your buck.

As I mentioned, absorption rates of non-heme iron can be an issue...however there is a way to optimise this! By combining plant-based sources iron with foods rich in ascorbic acid - in other words Vitamin C - you will ensure that absorption of iron from plant-sources remains on point. Foods rich in Vitamin C include citrus fruits, red, yellow and green peppers, kiwi, sweet potato. So combine your spinach and kale with some bell peppers; drizzle some lemon juice onto your oatmeal or overnight oats; or make sure you pack your tempeh or tofu buddha bowls with some baked sweet potato. The combinations are endless, but just know this - iron on a plant-based diet will not be a problem!

An infographic I created for Instagram which highlights some of the primary iron-rich plant based foods
An infographic I created for Instagram which highlights some of the primary iron-rich plant based foods

Summary

You can easily meet your iron needs while on a plant-based diet. With a little bit of knowledge of adding Vitamin C for optimal absorption, you are set to be in a good place as far as your iron intake goes. Remember as I said at the start, iron deficiency is not something that is exclusive to those on a plant-based diet - it's the most common nutrient deficiency in the world. Given that the percentage of the world's vegan population is still such a minute amount, it just shows that watching your iron intake applies to every dietary framework. If you're in doubt, it would be best to go to your doctor or GP and get a full blood panel, to get an idea of where your haemoglobin levels are at.

References:

1. Iron: Food Fact Sheet (The Association of UK Dieticians)
2. Isabel Young et al: Association between Heme and Non-Heme iron intake and Serum Ferritin in healthy young women (Pub Med)
3. Sukru Gulec, Gregory J Anderson & James F Collins: Mechanistic and regulatory aspects of intestinal iron absorption (Pub Med)
4. Department of colorectal surgery and oncology, Shengjing Hospital of China Medical University: Intakes of heme iron and zinc and colorectal concer incidence: a meta-analysis of prospective studies (Springer)
5. Amanda Jane Cross, Jim Pollock and Sheila Bingham: Heme, not protein or inorganic iron, is responsible for endogenous intestinal N-nitrosation arising from red meat (American Association for Cancer Research)
6. Metabolic syndrome (Mayo Clinic)
7. James D Cook, Manju B Reddy: Effect of ascorbic acid intake on non-heme iron absorption from a complete diet (The American Journal of Clinical Nutrition)