Iron Deficiency Anemia: How Our Microbiome Impacts Iron Absorption

Iron Deficiency Anemia: How Our Microbiome Impacts Iron Absorption

by Andréanne Martin, Registered Dietitian

Iron deficiency is the most common nutritional deficiency in the world, often affecting women, vegans, vegetarians, and endurance athletes the most. It occurs when our body doesn’t have enough iron to make hemoglobin, the protein in red blood cells that carries oxygen throughout our body.

The symptoms of iron deficiency anemia often start slowly, with many people not realizing they have it until the anemia worsens. The symptoms of iron deficiency anemia are1:

  • Feeling weak or tired more easily
  • Feeling dizzy
  • Feeling moody or cranky
  • Feeling short of breath
  • Trouble concentrating
  • Pallor
  • Headaches

Iron balance in our body is extremely critical. While iron is an important nutrient that we need to transport oxygen through our body, too much of it can also form toxic oxidative radicals. Because of this, our body tightly regulates the uptake and concentration of iron in our body – this is where our digestive system, including our microbiome, comes in.


Iron Gate: How Our Body Regulates the Absorption of Iron

Our liver plays a significant role in regulating our iron levels. The cells of the liver (aka hepatocytes) can take information about circulating iron levels in our body, and in response, secrete regulatory molecules which will either inhibit the uptake of iron or increase it. One of these regulatory molecules is the hormone hepcidin.2 When iron levels are high, hepcidin binds to the iron transport channel (located primarily in our small intestine) and prevents our gut cells from absorbing iron. When iron status is low on the other hand, hepcidin release is inhibited, keeping the channels free to absorb iron from the diet.

What is interesting to note, is that inflammatory cytokines (that are released during times of illness or injury) also increase the release of hepcidin, blocking the absorption of iron.2


Iron and Our Microbiome

Iron can alter our microbiome, as it contributes to the growth and survival for many of the bacterial species living in our gut. In fact, it has been known for a long time that iron availability can enhance the expression of virulent factors in pathogenic bacteria.3

Although most of the absorption of dietary iron does occur in the small intestine, our colonic absorption may play a contributing factor to our overall iron levels; particularly interesting to note if you suffer from iron deficiency anemia.

Prebiotic fibre is known to change our microbiome for the better. When we eat this type of fibre, our gut bacteria ferment it, creating a group of metabolites known as Short-Chain Fatty Acids (SCFA), which act as further fuel to keep our good bacteria healthy and happy. In pigs, the consumption of prebiotic fibre was shown to increase iron absorption.3 It is believed this may be, in part, due to the production of the SCFA, lactic acid, which can lower the pH of the colon making iron more soluble, and thus easier to absorb. SCFAs may also be responsible for promoting healthy epithelial cells (aka the cells lining our gut), enhancing their absorptive surface.3

Looking more specifically at human studies, lactic-acid fermented foods, have been shown to significantly increase iron absorption. Again, the thinking is that these foods can lower pH of the colon (increasing the solubility of iron), and decrease phytate levels (which are known to bind iron and prevent its absorption).4


Iron Deficiency Anemia: Taking a Holistic Approach

If you think you may be suffering from iron-deficiency anemia, the first step is to visit your doctor and have a blood test to confirm your suspicions. As too much iron in the diet can cause very serious health outcomes, you should never try to diagnose or treat low iron yourself.

If you do discover you have low iron levels, likely you will be advised to start taking an iron supplement as well as increase the amount of iron-rich foods in your diet. These are important first steps, but increasing the absorption of iron and improving your digestive health will also go a long way in supporting your path to recovery.

Beyond increasing iron-rich foods (and taking an iron supplement), here are some tips to help improve iron absorption:

Pair Iron-Rich Foods with Vitamin C: this is especially important when consuming plant-based sources of iron (non-heme iron). Vitamin C has been shown to prevent unabsorbable compounds from forming and keeps iron in the form that is required for uptake into the mucosal cells of our intestine.5

Take iron supplements away from dairy: calcium has been shown to compete with iron absorption. Try taking your iron supplement 2 hours before or after consuming any dairy.

Support your Good Bacteria: as it appears the production of SCFAs (specifically lactic acid) can help improve the absorption of iron it is wise to increase your consumption of lactic-acid rich foods. Drinkable Bio-K+ is both a fermented food and probiotic supplement. The three unique Lactobacillus strains found in every bottle have been clinically shown to travel from your mouth to your colon where they can work to improve the environment for good bacteria to grow and flourish.

Limit Your Consumption of High Phytate Foods: grains, legumes, and nuts (that have not been sprouted or fermented) contain a compound called phytic acid which is known to inhibit the absorption of iron. If you are suffering from low iron, it may be a good idea to limit these foods and focus on lots of leafy greens and vitamin C-rich foods and veggies. If you are a vegetarian or vegan, you may want to work with a dietitian to ensure you have strategies in place to get enough protein without limiting your iron absorption.

Limit Coffee and Tea: coffee (even decaf) and tea contain tannins, another compound known to inhibit the absorption of iron. Limiting these beverages while you work to improve your iron levels may be beneficial for enhancing absorption.


If you are suffering from iron deficiency anemia, increasing your iron intake is only one part of the equation. Improving your digestive health and optimizing your diet to absorb iron better plays a significant role in helping to improve your symptoms and returning iron levels to normal. And while there are still more human studies needed to understand the connection between the microbiome and chronic inflammation fully, we do know that inflammation alters hepcidin expression. Focusing on gut-health and consuming an anti-inflammatory diet to help reduce chronic inflammation in the body may also be worth considering if you do suffer from low iron stores.


If you have questions about the microbiome, gut health, or nutrition, leave us a comment below. For more healthy inspirations, join our community. To stock up on Bio-K+, head to our store locatorContact us or follow us on Facebook and Instagram.









Andréanne Martin
About the author
Andréanne Martin, Registered Dietitian
Andréanne Martin is a dietitian and nutritionist who drives projects that enable her to promote healthy lifestyles in order to help as many people as possible to feel better.
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