Non-Haem Iron Vs Haem Iron – What Is The Difference?

When talking plant-based eating the first things we worry about is our Protein, Calcium and Iron right? I get it, I was freaked out about these things too.
But the one thing that is going to help you is knowledge. Understand the ‘basics’ around these macro and micronutrients and you can sit back assured that all your nutrient needs are being met.

So let’s talk Iron. What is it?

Iron is an essential mineral for the body, it is responsible for oxygen transport in the blood and muscles, fatty acid metabolism and the maintenance of a healthy immune system. You need it.
But would you be surprised to find out that the workings of our body ONLY allow for 1-2mg of Iron absorption from food at any one time?  A tiny amount hey!
And can you get that amount from JUST plants?
YES, you can and actually IMPROVED absorption of Iron due to ALL the plant nutrients that build a healthy and robust Gut Microbiome – the basis of Iron in the body.
Here’s a common scenario I come across in my Clinical practice.  Now I want you to read this ‘scenario’ and then read the info about Iron and then tell me – what does the Client need to do?? (P.S. All other conditions have been ruled out, the client eats meat).
CLIENT: Had blood tests done – shows low Iron. Recommended to take supplements and eat more Iron rich food in the form of meat. If really low, may also get an Iron infusion.
The client takes 1 Iron tablet a day, starts eating meat, and feels better for a while, in fact, the old self has come back and ‘Avenger’ energy levels are reached- problem sorted!
6-12 months later – blood tests are done again and it is still low. Energy levels have declined again. Huh?? How does that work?? The client has been taking supplements, eating Iron-rich foods and still low in Iron.
Read on and let me know (at the end in the comments section) what you see as the issue. P.S. I’m not asking you to do my work for me, hehe ?


Iron supplements
Example supplements

What’s the go-to for low Iron? Fast-release supplements, usually with ‘ferrous (iron) sulfate’, release iron quickly. Because it’s the cheapest ‘form’ it is the most commonly prescribed supplement. However the oral tablets, due to iron deposition can result in chemical irritation of the Gastrointestinal mucosa and a greater frequency of adverse effects.  While there are slow release supplements, due to the time taken to dissolve, a major proportion is not available for absorption. [5] In fact one tablet = 70-100mg Iron greatly exceeds the amount that can be absorbed.
Evidence reveals an excess of unabsorbed iron results in undesirable side effects “at the intestinal host–microbiota interface” and can stimulate the growth of bacterial pathogens making them more virulent and can even exaggerate infection. [1] As the body has NO method of excreting excess iron it is stored in organs and joints. It can overload the liver and create other health problems such as arthritis, heart disease, diabetes, endocrine, and even sexual dysfunction. [2] [3] [4]


Iron breakfast
Getting your needs from food

So how much Iron is absorbed from what you eat? (or supplements) Actually, very little. For every 10 mg of iron you consume, only 1–2 mg is absorbed. Mostly in the duodenum (first part of your small intestines). About two-thirds of the iron in the body is produced in red blood cells produced by Bone Marrow (see image below) and it is your Gut Microbes that regulate and sustain this steady production of blood cells (see image below). Antibiotic use can impair this production by depleting the intestinal microbiota. And, over time, with poor diet, alcohol, medications (painkillers, antihistamines etc), second-hand antibiotic ingestion (animal products) the intestinal microbiota can be further depleted which can result in low iron stores. [3] [6] 

There are Two types of Dietary Iron
  • Haem iron – found mainly in animal sources*.
  • Non-haem iron – found mainly in beans, legumes, nuts, seeds, grains, and vegetables.

10mg of Dietary Iron can easily be sourced from Non-haem Sources. In fact, research shows that Iron deficiency is no more common among vegetarians than among meat-eaters.
*Haem promotes the formation of Nnitroso compounds and also contains iron. Free iron can lead to the production of free radicals.  Another hypothesis is that dietary haem induces colonic cytotoxicity and hyperproliferation. [7] 
Here are some examples of plant-based foods that contain ample amounts of Iron. There are a lot more but here is a snapshot:

Cacoa source of iron
Cacoa powder, raw


Food Qty Iron (Mg)
Cacao powder, raw 85g 10
Cashews 1 cup 8.2
Spinach (cooked) 1 cup 6.4
Almonds 1 cup 5.3
Prunes 1 cup 5
Macadamias 1 cup 5.0
Pistachios 1 cup 5.0
Sesame seeds 1 tbsp 4.2
Lentils (cooked) ½ cup 3.3
Chickpeas (cooked) ½ cup 2.4
Lima beans (cooked) ½ cup 2.3
Blackstrap molasses 2 tsp 2.3
Kidney beans (cooked) ½ cup 2.2
Navy beans (cooked) ½ cup 2.2
Tofu 70g 2.1
Pumpkin 1 cup 2.1
Swiss Chard (cooked) ½ cup 2.0
Quinoa (cooked) ½ cup 1.4

So, as you can see, no problem getting your Iron needs met with plants ?


Focusing on a single nutrient, to the exclusion of all of the other vitally important nutrients, can lead to an ‘excess or depletion’ of other minerals which can result in troubling and serious conditions later on. This information is to put your mind at rest, so you know your Iron requirements are being met.
But if you are CURRENTLY low in iron or have a propensity for it to be low, until you improve your Gut Microbiome, it is important to incorporate factors that BOOST absorption and ELIMINATE those that REDUCE absorption.

Factors that BOOST Iron absorption in the body are:

Vitamin C (abundant in plants and can increase absorption up to six-fold), Slight steaming of some vegetables e.g. broccoli’s iron absorption rises from 6% to 30% when slightly cooked.

Factors that REDUCE Iron absorption in the body are:

Soy protein, Coffee and Black tea (tannins), Phytates in eating too many beans and legumes (soak first to reduce or use canned), Vitamin A Deficiency and too much Calcium.
If you are concerned about your Iron levels it is highly recommended that you get a Blood Test done as self-supplementation, in the presence of normal (or even low-normal stores) is potentially harmful. Also, signs and symptoms of a deficiency such as fatigue and lethargy are common signs of other health conditions. So, it is always best to get further investigation through blood tests (see below for a breakdown of each area) if you are worried.
So you’ve read the information above. What is a good step forward for the Client?
Feel free to comment below. But if you don’t have a clue, here is the answer…


The best way to improve Iron absorption and production in the body is through improving the function of the Gut Microbiome and by continued consumption of whole plant-based foods that contain Iron.
Accumulating evidence is pointing to the restoration and function of the Gut Microbiome as a key player for IRON absorption, assimilation, and production in the body. In fact, by improving Short Chain Fatty Acid (SCFA) production through prebiotic and probiotic foods lowers the luminal pH and thus can inhibit the growth of pathogenic bacteria and may contribute to an increased solubility of luminal iron and other minerals –  “This, in turn, may enhance host mineral absorption, but also bacterial mineral uptake, from which both the host and bacteria could benefit”. [1]
While the Recommended Dietary Intake (RDI) of Iron depends on your age, gender, and specific health requirements/conditions, here is a general guide. [4]
Age/Mg req. daily. 7-12 mths. 11 mg. 1-3 yrs. 9 mg. 4-8 yrs. 10 mg
Male Age/Mg req. daily. 9-13 yrs. 8 mg. 14-18 yrs. 11mg. 19-70+ yrs. 8mg
Female Age/Mg req. daily. 9-13 yrs. 8 mg. 14-18 yrs. 15mg. 19-50 yrs. 18mg. 51-70+ yrs. 8mg
Pregnancy Age/Mg req. daily.14-50 yrs. 27mg.
Lactation Age/Mg req. daily. 14-18 yrs. 10mg. 19-50 yrs. 9mg
Would love to hear your thoughts. Nat xx
To read more of Nat’s informative articles see her articles here 


  1. Kortman, G.A.M. et al. (2014). Nutritional iron turned inside out: intestinal stress from a gut microbial perspective. FEMS Microbiology Reviews, Volume 38, Issue 6.
  2. Payne SM Finkelstein RA (1978) The critical role of iron in host-bacterial interactions. J Clin Invest 61: 1428–1440.
  3. Geisser, P., & Burckhardt, S. (2011). The pharmacokinetics and pharmacodynamics of iron preparations. Pharmaceutics3(1), 12-33. doi:10.3390/pharmaceutics3010012
  4. http://www.irondisorders.org/iron-overload (2009) Iron disorders institute.
  5. Zariwala, M. G., Somavarapu, S., Farnaud, S., & Renshaw, D. (2013). Comparison study of oral iron preparations using a human intestinal model. Scientia pharmaceutica81(4), 1123-39. doi:10.3797/scipharm.1304-03
  6. Osefsdottir KS, Baldridge MT, Kadmon CS, King KY. Antibiotics impair murine hematopoiesis by depleting the intestinal microbiota. Blood. 2017;129(6):729-739.
  7. World Cancer Research Fund / American Institute for Cancer Research. Food, Nutrition, Physical Activity, and the Prevention of Cancer: a Global Perspective. Washington DC: AICR, 2007

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