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Improving iron absorption

Pregnancy, Nutrition | March 24, 2021 | Author: Naturopath

Circulatory system, pregnancy, women's health

Improving iron absorption

There are many reasons people may be low in iron and it is important to establish why this is. The most common causes of iron deficiency are due to insufficient iron in the diet, haemorrhage (most commonly through trauma or gastrointestinal lesions), or decreased iron absorption.

Absorption is the way iron levels are managed in the body, whereas iron excretion is an unregulated process and occurs through loss in sweat, menstruation, exfoliation of hair and skin cells, and from the rapid turnover and excretion of enterocytes (intestinal absorptive cells which line the inner surface of the large and small intestine). Iron from food sources often has a low solubility and low bioavailability.

Blood loss, malabsorption and increased iron requirements

Blood loss may be due to excessive menstrual bleeding, digestive ulcers or cancer for example. Ulceration in the digestive tract may be due to Hiatus hernia (causing irritation on the digestive mucosa (Cameron’s erosions) resulting in bleeding. Inflammatory bowel diseases and coeliac disease are examples of conditions that degrade the mucosa of the duodenum and result in decreased iron absorption. Menstruating women of reproductive age, pregnancy and breastfeeding require significantly increased amounts of iron.

Whist the reasons for low-iron status is being explored and diagnosed it is important to maintain regular iron intake as directed by your doctor. In some instances, injections of iron are suggested to quickly replete iron status. Following are some suggestions to help to improve iron status.

The importance of Iron

Iron is found in the body mostly in erythrocytes (red blood cells) as the heme compound of hemoglobin. It is stored in ferritin and hemosiderin compounds and in muscle as myoglobin. It is also found bound to proteins (hemoprotein), non-heme enzymes, involved in oxidative-reduction reactions and the transfer of electrons (cytochrome and catalase).

Iron is essential for the development of red blood cells (erythropoiesis) - needed for the transport of oxygen around the body. Red blood cells contain the largest amount of iron in the body and are also the greatest user of iron. Left unchecked, iron deficiency leads to anaemia. This can put a strain on the heart as it has to pump harder to transport oxygen around the body and may eventually lead to arrythmia, enlarged heart and heart failure.

Iron is also essential for the synthesis and maintenance of DHA, mitochondrial function, and many enzymatic reactions needed for the survival of cells.

Not only does too little iron cause a problem, but so can too much. Absorption of iron, and factors affecting bioavailability, are tightly regulated in the body.

Iron absorption

When iron is exposure to oxygen it forms highly insoluble oxides which are unavailable for absorption in the human gastrointestinal tract. Human intestinal absorptive cells (enterocytes) function to reduce insoluble ferric (Fe3+) to absorbable ferrous (Fe2+) ions. To be absorbed, iron must be in the ferrous (Fe2+) state or bound by a protein, such as heme. Most of the absorption of iron occurs in the duodenum and the proximal jejunum of the digestive system. 

The low pH of gastric acid in the proximal duodenum allows a ferric reductase enzyme to convert the insoluble ferric (Fe3+) to absorbable ferrous (Fe2+) ions. After ferric iron is reduced to ferrous iron in the intestinal lumen, a protein, divalent metal cation transporter 1 (DMT1), transports iron across the apical membrane and into cells. Once iron enters circulation in the body it is used for physiological functions or goes into storage.

What can interfere with iron absorption?

There are some foods, medications, vitamins and digestion conditions which inhibit iron absorption.

Inhibitors of Iron absorption

Phytate – found in plant-based foods depending on the amount consumed.

Polyphenols – found in black and herbal teas, coffee, wine, legumes, fruit, vegetables and cereals inhibit non-heme iron absorption.

Oxalic acid in spinach, chard, beans and nuts can bind iron and prevent absorption.

Saponins. Found in legumes - such as chickpeas, soybeans, peas and beans; wholegrains, asparagus, garlic, onion and spinach.

Calcium inhibits both heme and non-heme iron.

Proteins such as casein and whey (dairy), egg whites and soy protein could also prevent iron absorption.

Proton-pump inhibiting drugs. Gastric acid also plays a key role in plasma iron homeostasis. Proton-pump inhibiting drugs can greatly reduce iron absorption.

Changes in microbiota. Alterations in iron homeostasis (balance) may have an effect on the luminal iron content in the intestine, changing the composition of bacteria present in the intestine. When iron levels are reduced infections can occur, due to the influence on the composition of gut microbiota.

Inflammation in the body can also alter iron (and other nutrients) to limit microbial growth.

What can help iron absorption

Enhancers of Iron absorption

Vitamin C can counteract the effects of all iron inhibitors when included in the diet at the same time as non-heme iron (meal containing large number of vegetables).

Probiotics and prebiotics. Digestive health is reliant on a diet which contains wholegrains, fresh fruits and vegetables, nuts and seeds to help fight diseases and maintain proper balance of the gut microbes. Probiotics have been shown to help with iron absorption by acting as carriers for iron, are able to convert unavailable iron to an available form and create metabolites which are able to indirectly increase absorption of iron into the gut.

  • Probiotics are live microorganisms which can improve the microbial composition of the intestine. Some bacteria such as Bifidobacterium longum and Lactobacillus acidophilus, can prevent intestinal inflammation. Many studies that examined the effect of the probiotic Lactobacillus plantarum 299v on iron absorption was found to significant increase iron absorption.
  • Prebiotics are non-fermented ingredient from foods which feed probiotics, improve microbial activity and improve the absorption of minerals. Examples of useful prebiotics are inulin and fructo-oligosaccharide.

Increasing iron-rich foods in the diet

Iron-rich foods

Iron in foods is available in 2 forms. Heme iron available from animal sources and non-heme iron form vegetable sources. Heme iron is the iron more easily absorbed by the body.

Heme sources include:

  • Beef
  • Pork
  • Lamb
  • Poultry
  • Seafood
  • Kangaroo

Non-heme sources include:

  • Spinach and other dark green leafy vegetables (contain vitamin C also)
  • Dried or concentrated tomatoes 
  • Potatoes with skin
  • Legumes such as: peas (black-eyed and chickpeas), beans (kidney, white, lima, and navy beans), soy-based products (tempeh, tofu, natto and soybeans)
  • Lentils 
  • Nuts: cashews, almonds, macadamia and pine (pesto and nut butters)
  • Seeds such as: flaxseeds, pumpkin and sesame (tahini and hommus for example)
  • Wholegrains - spelt, quinoa, amaranth and oats
  • Dark chocolate

Other non-heme sources are foods which have fortified with iron. These might include breakfast cereals and some beverages. Iron fortification is a process where vitamins and minerals are used to improve the food nutritional quality of the food.

Cast-iron cookware can add a small increase of iron in foods during the cooking process.

As noted previously some foods can inhibit the absorption of iron due to anti-nutrients they contain. These foods are best eaten away from iron-rich foods or in smaller amounts. The inhibiting components can be reduced using by consuming as sprouts, fermenting or soaking. For example:

Phytates (phytic acid) such as whole grains, nuts, seeds and legumes can block the absorption of many minerals and Lectins such as peanuts, soybeans and beans are also responsible for reducing absorbency of many minerals, including iron. 

Phytates and lectins can be reduced in foods by fermenting, soaking or sprouting before consuming.

Tannins found in tea and coffee contain high amounts of tannins which can block the absorption of iron. 

Tannin content can be reduced by boiling. Limit amounts consumed especially when combining with iron-rich foods.

Include non-heme foods with heme foods. Meat and vegetables or beans followed by some vitamin C- rich fruit. Cooking vegetables can often help release non-heme iron.


  • Vitamin A helps release stored iron
  • Vitamin C helps iron absorption
  • Iron supplement as recommended by your doctor
  • L- Lysine (an amino acid) helps your body absorb iron
  • Probiotic to support intestinal mucosa and iron absorption. Lactobacillus. plantarum (FS2), L. plantarum 299v, L. fermentum, Streptococcus thermophilus, L. acidophilus and Bifidobacterium bifidum and B. longum are suggested strains.

www.superpharmacy.com.au  Australia’s best online discount chemist


Biochemistry, Iron Absorption https://www.ncbi.nlm.nih.gov/books/NBK448204/

A Red Carpet for Iron Metabolism https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5706455/



Iron absorption: biochemical and molecular insights into the importance of iron species for intestinal uptake https://pubmed.ncbi.nlm.nih.gov/12427107/

Biochemistry, Iron Absorption https://www.ncbi.nlm.nih.gov/books/NBK448204/

Gut Microbiota and Iron: The Crucial Actors in Health and Disease https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6315993/


The Impact of Tannin Consumption on Iron Bioavailability and Status: A Narrative Review https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5998341/

(2) Iron Supplementation Influence on the Gut Microbiota and Probiotic Intake Effect in Iron Deficiency—A Literature-Based Review https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7400826/


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