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Iron deficiency and gut conditions - What's the connection? Tips to help dietary iron absorption

This article looks at why iron deficiency is more prevalent in suffers of gut related conditions and offers simple tips to ensure you can get more iron from better meal choices and hopefully feel less discomfort, with more energy in the process.

Iron deficiency anaemia is a prominent feature in inflammatory and gut sensitivity conditions. According to Coeliac UK a quarter of adults are estimated to be anaemic due to iron deficiency upon diagnosis with coeliac disease. The screening for anaemia is part of the range of blood tests that are carried out for suspected irritable bowel syndrome (IBS), to rule out Coeliac disease. With irritable bowel disease (IBD), such as Crohn’s disease and ulcerative colitis, iron deficient anaemia is reported to affect up to 90% of suffers, the elderly being markedly more prone to deficiency (1).

If you have been tested positive for anaemia and have or develop gut symptoms, it’s always worth asking your GP to check for Coeliac disease.

It’s worth mentioning that symptoms of iron deficiency are most commonly experienced as tiredness, lack of energy and sometimes shortness of breath. These symptoms however are remarkably similar to vitamin B12 deficiency, another form of anaemia. The simple rule is that if you have an underlying gut condition and feel regularly fatigued you should establish the type of anaemia through a standard blood test.

Diet alone is often not enough to increase a deficiency of iron, termed clinical iron deficiency anaemia. High-dose iron supplementation is often offered at a rate that far exceeds the recommended daily allowance of 14.8 mg for females. The main reason for this is that iron is not well absorbed but the effect of high supplementation is often seen in digestive side effects, such as abdominal pain, constipation, and nausea.

Low Iron and absorption problems

One possible reason coming to light explaining high dosage iron side effects and a potential cause for iron deficiency is the relationship between Inflammatory gut conditions and our production of hepcidin. Hepcidin works to regulate the level of circulating iron and levels of hepcidin rise in the presence of inflammation. It has been seen that iron supplementation can cause the level of inflammation in the gut to increase in studies conducted on IBD patients (2). The increased level of gut inflammation then interferes with iron absorption by causing hepcidin levels to rise which has the effect to prevent iron absorption. Research has shown that when it is essential to take iron supplements, alternating the day of taking the supplement seems to increase iron absorption by reducing levels of hepcidin and inflammation (3).

There is some light at the end of the tunnel for those who have inflammatory gut conditions. Recent studies (4) are showing the curcumin, the active ingredient in the spice turmeric, significantly increases iron levels through the reduction of gastric inflammation and hepcidin levels. Adding this spice regularly to your meals, or taking it in a supplement form could be supportive and naturally increase circulating iron levels.

Iron and the gut microbiome

Another side to iron supplementation and the reported adverse effects is the detrimental changes that take place in gut bacteria within the microbiome.

Our protective immune cells compete for the supply of iron against increasing levels of pathogenic (bad) bacteria that consume iron for growth. These problematic bacteria then colonise and consequently cause intestinal injury and inflammation (5). A study investigating iron supplementation in African children found that there was an increase in the number of enterobacteria (bad bacteria) and a decrease in lactobacilli (good bacteria) which correlated also with gut inflammation (6).

In the light of the undesirable effects that iron supplementation may have on the gut microbiome what else should be we be considering?

Ensuring the diet includes plenty of naturally high iron containing foods is essential. There are some facts worth knowing about how iron from food is absorbed which will help you to ensure your food choices give you the best supply of naturally occurring dietary iron.

Iron form food comes in two forms; heme-iron from animal products such as fish, red meats and poultry, and non-heme iron which is found in plant-based foods like grains, beans, vegetables, fruits, nuts and seeds. Non-heme iron is also found in eggs, milk and dairy products.

The most important point about these two different forms of iron is that they are absorbed at very different rates. We process and absorb approximately 20-30% of heme-iron and only 5-10% of non-heme iron from the levels listed on the nutrition labels of these foods. This is useful information for vegetarians and vegans who need to plan food choices for this reason more carefully.

There is one more crucial point to mention here on this subject. The absorption of iron is affected by other dietary elements notably calcium, phytates and tannins. Research (7) suggests that tea and coffee contain elevated levels of tannins and should be avoided immediately before and after eating iron containing foods. Dairy foods containing high levels of calcium can bind to the heme-iron within this group of iron foods preventing iron absorption. Consider switching from having large amounts of cheese or dairy based sauces with meat, fish or poultry to a portion of spinach or kale which contains both calcium and non-heme iron.

On a positive note, vitamin C foods increase the absorptive process of dietary iron. The inclusion of red and green peppers, broccoli, kale and tomatoes will be excellent accompaniments to iron containing foods.

Good sources of heme-iron include:

  • Beef & chicken liver

  • Oysters, clams & mussels

  • Beef

  • Tinned sardines

  • Turkey

  • Chicken

  • Fish – salmon, halibut, and haddock

  • Ham

  • Veal

Good sources of non-heme iron include:

  • Spinach – cooked

  • Seeds - pumpkin seeds, sunflower seeds

  • Tofu

  • Beans & lentils – chickpeas, white beans, red kidney beans, soybeans, black beans, and lima beans

  • Baked potato with skin - without skin, a potato’s iron is minimal

  • Prune juice

  • Dried fruits - raisins, apricots, etc.

  • Nuts - cashews, almonds, pistachio, etc.

New research is looking at ways to help improve Iron absorption

Taking prebiotics improves the absorptive area of the gut and increases iron absorption

The use of prebiotics and probiotics are being studied as a means to potentially improve iron absorption.

As mentioned above high levels of iron from iron supplements can create an imbalance within the gut microbiome where it acts as food for disruptive types of bacteria. These troublesome bacteria then crowd out our beneficial bacteria which has the effect of reducing our natural gut immunity.

Prebiotics have been heavily studied in their role of increasing beneficial bacteria and the production of short chain fatty acids (SCFA). SCFA’s have highly beneficial influences on the quality of the gut lining in increasing the absorptive area of the gut, acting in an anti-inflammatory way to reduce hepcidin levels and improve iron solubility. Pre-biotics made from galacto-oligosaccharides (GOS) have been proven in human studies to increase iron absorption (8).

Galacto-oligosaccharides are found in the following foods:

  • Jerusalem artichoke

  • Dried lentils

  • Lima beans

  • Chickpeas

  • Red kidney beans

  • Green peas

If these foods are new to you, try introducing small quantities every few days while you grow new and beneficial bacteria. Starting with large portions may produce bloating. These wonderful foods really can create a whole new environment in your gut.

Probiotics are also highly beneficial to iron absorption

If you think that prebiotics feed our good bacteria, probiotics are literally the live microorganisms that populate our gut. It is known that the levels of good bacteria in those with compromised or gut related conditions are lower than in the average healthy population, particularly the groups responsible for creating the right environment for iron absorption. The group of beneficial bacteria that produce lactic acid create an environment more suitable to iron absorption, by reducing the pH level. A controlled study of female athletes (9), a group known to be frequently low in iron, showed an improvement in iron status against the control group after taking the probiotic Lactobacillus plantarum 299v for 12 weeks. It seems that taking pre and probiotics during iron supplementation helps to reduce the negative and inflammatory effects of introducing high levels of iron into the gut.

Lactoferrin - an alternative to iron supplementation

Lactoferrin is a protein found naturally in milk from cows. In the context of iron, lactoferrin's main function within in the body is to bind to and transport iron. In a 2009 study (10) of pregnant women with iron deficiency anaemia, half were given 100mg of lactoferrin twice daily and the other half received 520mg of ferrous sulfate once a day. In 30 days both groups showed the same increase in iron status. The lactoferrin group experienced no side effects while the ferrous sulfate group felt significant levels of abdominal pain and constipation. Earlier work (11) concluded that lactoferrin improved iron transport out of the intestinal cells into the blood and suggested it should be considered as an alternative option for iron deficiency anaemia where inflammation and sensitivity is present.

The information contained in this article is for informational purposes only and not intended as a substitute for advice from your GP. If you are taking iron supplementation please discuss any changes to your medications with you GP.


1. Guagnozzi. D, Lucendo, A. (2014) Anaemia in inflammatory bowel disease: A neglected issue with relevant effects

2. Bergamaschi, G. et al (2012) Serum hepcidin in inflammatory bowel diseases: biological and clinical significance Inflamm Bowel Dis. 2013 Sep;19(10):2166-72

3. Stoffel, N. (2019) Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica. 2020 May; 105(5): 1232–1239.

4. Laine, F. et al (2017) Curcuma decreases serum hepcidin levels in healthy volunteers: a placebo-controlled, randomized, double-blind, cross-over study. Fundam Clin Pharmacol, 31(5):567-573. doi: 10.1111/fcp.12288. Epub 2017 May 7.

5. Paganini, D. Zimmermann, M. (2017) The effects of iron fortification and supplementation on the gut microbiome and diarrhoea in infants and children: a review Am J Clin Nutr. 2017

6. Zimmermann, M. Chassard, C. et al (2010) The effects of iron fortification on the gut microbiota in African children: a randomized controlled trial in Cote d'Ivoire. Am J Clin Nutr. doi: 10.3945/ajcn.110.004564. Epub 2010 Oct 20.

7. Salma, F. A. et al (2017) A 1-h time interval between a meal containing iron and consumption of tea attenuates the inhibitory effects on iron absorption: a controlled trial in a cohort of healthy UK women using a stable iron isotope - PubMed (

8. Jeroense, F. M. et al (2019) Consumption of Galacto-Oligosaccharides Increases Iron Absorption from Ferrous Fumarate: A Stable Iron Isotope Study in Iron-Depleted Young Women.

9. Axling, U. et al (2020) The Effect of Lactobacillus plantarum 299v on Iron Status and Physical Performance in Female Iron-Deficient Athletes: A Randomized Controlled Trial. Nutrients. 2020 Apr 30;12(5):1279. doi: 10.3390/nu12051279.

10. Nappi, C et al, (2009) Efficacy and tolerability of oral bovine lactoferrin compared to ferrous sulfate in pregnant women with iron deficiency anemia: a prospective controlled randomized study. Acta Obstet Gynecol Scand. 2009;88(9):1031-5. doi: 10.1080/00016340903117994. PMID: 19639462

11. Paesano, R. et al (2006) Oral administration of lactoferrin increases hemoglobin and total serum iron in pregnant women. 2006 Jun;84(3):377-80. doi: 10.1139/o06-040. DOI: 10.1139/o06-040

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