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The Guts of Iron Deficiency

Updated: Jun 7, 2023

With 25% of the world’s population deficient in iron, it’s the most common nutrient deficiency globally. Evidently this is a deficiency not limited to those who don’t eat animals, though the plant based community are at greater risk.

This article will explore everything you need to know about iron, deficiency and recovery.

What is iron?

Iron is an essential nutrient for most living organisms. Among other roles, it’s used to produce haemoglobin which is what enables red blood cells to transport oxygen throughout the body. It is therefore crucial for energy production. Ferritin is the iron storage protein. In the discussion of iron, I use the analogy of a public bus, in which you could consider ferritin to be equivalent to the number of passengers waiting at the bus stop to get onboard.

What happens when iron levels are low?

Low iron comes in varying degrees, from initially having low iron stores (as indicated by low serum ferritin and transferrin); to early iron deficiency (indicated by decreased serum transferrin saturation) to Iron Deficiency Anaemia (indicated by low haemoglobin and haematocrit as well as reduced mean corpuscular volume (MCV)).

It’s important when assessing iron levels, to avoid simply viewing serum iron. For a complete view of oxygen carrying capacity, review and request the following from your Dr:

  • Serum Ferritin. The number of passengers waiting at the bus stop.

  • Serum Transferrin. The iron transport protein which could also be thought of as the number of buses available on the road.

  • Transferrin Saturation. A measure of how much iron is attached to the iron transport protein which could also be thought of as the number of seats filled on the buses. We want the seats to be full. We want people (ferritin) getting to their desired destination

  • Complete Blood Count. This will help to determine if sub-optimal iron levels are causing a change in red blood cell volume or haemoglobin concentration and therefore whether a change in any of the levels above are resulting in Iron Deficiency Anaemia – the end stage of low iron levels.

Regardless of whether anaemia is present, low iron and/or ferritin levels may manifest with many symptoms including:

  • Dizziness, headache and shortness of breath.

  • Fatigue.

  • Heart palpitations and/or racing heart beat.

  • Brittle nails.

  • Restless legs.

Who is at risk of low iron levels?

  • Menstruating females. Particularly those suffering from heavy periods (Menorrhagia).

  • Those suffering from blood loss, possibly caused by Peptic Ulcers, Colorectal Cancer or Hiatus Hernia.

  • Those with Irritable Bowel Disease (IBD), Coeliac Disease, Small Intestinal Bacterial Overgrowth (SIBO) or other conditions causing disturbance to nutrient absorption.

  • Those on a plant based diet or with poor dietary intake of iron.

  • Those with an eating disorder.

  • Those on stomach acid suppressing medication or with low stomach acid levels.

  • Frequent blood donors.

  • Pregnant and postpartum women.

How to prevent low iron levels?

1. Consume adequate amounts of dietary iron:

For most people, consuming the Recommended Dietary Intake (RDI) should be enough to prevent iron deficiency or Iron Deficiency Anaemia. In Australia, RDI’s are as below:

  • Male: 8mg/day.

  • Female (menstruating): 18mg.

  • Vegans and vegetarians: requirements are about 80% greater due to a lack of haem iron within the diet.

Dietary iron comes in two forms, haem (from meat, fish and poultry) and non-haem (nuts, seeds, legumes & green leafy vegetables). Non-haem iron is less readily available for transport across the intestinal lumen. For this reason, absorption of non-haem iron may be lower (about 10%, as compared to 18% from a standard western diet), though consuming a wide variety of iron containing plant foods and aiming for that inflated RDI can help vegans and vegetarians maintain adequate intake.

Great plant based sources of non-haem iron include:

  • Tempeh or tofu: 120 – 150g per serve and 3 - 5mg iron.

  • Lentils, chickpeas and kidney beans: ½ - 1 cup per serve and 4 – 12mg iron.

  • Pumpkin seeds, hemp seeds, flaxseeds and sesame seeds: 2 tbsp per serve and 1 – 3 mg iron

  • Almonds, macadamia and pine nuts: 2 tbsp per serve and 1 – 3 mg iron

  • Green leafy veg such as spinach, kale and swiss chard.

2. Support absorption of non-haem iron:

As non-haem iron is less readily absorbed, considering a few factors to support absorption will help to maximise the iron present in the plant-based diet.

  • Consume non-haem iron containing foods alongside vitamin C. Without an antioxidant present, absorption can’t take place. Great sources of vitamin C include berries, spinach, broccoli, capsicum and tomato.

  • Consume non-haem iron containing foods alongside vitamin A and β-carotene also enhance non-haem iron absorption. Great sources of β-carotene include carrots, sweet potato, spinach, kale and capsicum.

  • Phytates found in legumes, nuts and seeds can negatively impact non-haem iron absorption. Soaking or sprouting these foods prior to consuming can reduce the phytate content thereby supporting better iron absorption. Optimal gut health is also important as the right bacteria could play a role in breaking down phytates.

  • Avoid consuming tannins (found in tea, green tea and coffee) with haem-iron rich foods as these can impair absorption.

  • If using an iron supplement, don’t take them at meal times or near supplements containing zinc or calcium as these will also impair absorption.

3. Optimise gut health:

Remember, we are what we digest and absorb. Support the initial stages of digestion and ultimately absorption with adequate stomach acid. If you have a history of (or a suspicions of) Hypochloridria (low stomach acid), bitters (such as lemon juice, apple cider vinegar, dandelion and gentian) can be a good starting point for regaining adequate digestive secretions. Always avoid eating when stressed as the sympathetic nervous system will detract from digestive secretions.

It’s also important to consider and maintain the integrity of the intestinal lining as the junctions within it are responsible for regulating nutrient absorption. The presence of oxidative stress and inflammation has been shown to promote ‘loosening’ of the junctions which is otherwise commonly referred to as ‘leaky gut’. Reduce risk of inflammation in the gut by nurturing a thriving gut microbiome. You can read more about this in 'The Gut. Explained', but know this: the foundations of a healthy microbiome lie in consuming an abundance of fibre (prebiotics). Hopefully this isn’t too much of a concern for the majority of those consuming a plant-based diet, but 6 cups of non-starchy vegetables per day and a weekly goal of consuming at least 30 different plants is a great place to start.

The association between gut health and iron levels is an area of increasing research, there may be ways in which the gut supports iron levels that science can’t even yet explain.


For most on a plant-based diet, consuming more than adequate amounts of iron isn’t a challenge. The attention therefore needs to be placed on the practices being done around that consumption to support optimal digestion and absorption. This is why in my practice such focus is placed on eating behaviours and digestive health. This is the ‘guts of supporting adequate iron levels’, especially in the plant based community.

When the requirements for supporting optimal iron levels can’t be met then there may be value in supplementing. For two reasons I always recommend working with a practitioner on your supplement regime:

  1. While supplementing, it's key to uncover and address the underlying cause for low iron levels.

  2. While supplementing, it’s key to choose the right supplement and regime to suit your specific needs.

I hope this resource has been helpful. Leave your comments below or get in touch should you need assistance with your iron levels.



Young et al, 2018. Association between Haem and Non-Haem Iron Intake and Serum Ferritin in Healthy Young Women. Nutrients. 10, 1: 81.

Nutrient Reference Values for Australia and New Zealand. (accessed June 2020).

FoodData Central Search Results. (accessed June 2020).

Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. (accessed June 2020).

Saunders, 2013. Iron and vegetarian diets. The Medical Journal of Australia. 199, 4, S11 – S16. (accessed June 2020)

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