What you can do about stubbornly low iron levels

Written by Stephen Ward (MSc) on 6th August, 2021

Iron deficiency is common, especially among women, vegetarians, and anyone who is hypo-thyroid. It can make you feel, tired, dizzy, moody, and cause head aches as the body doesn’t have enough iron to make haemoglobin, the protein in red blood cells that carries oxygen around the body.

This lack of healthy red blood cells is known as iron-deficiency anemia. Resolving this anemia is a crucial first step of any healing program as it robs cells of the oxygen they need to function. If you suspect your have iron-deficiency anaemia, the first step is to talk to your doctor about testing to get confirmation.

Iron deficiency may explain persistent symptoms in between 30 to 50% of hypo-thyroid patients despite thyroid hormone therapy.

Iron balance is critical with too much iron leading to oxidative damage to our cells. This oxidative stress is associated with chronic fatigue, liver disease, and brain function. And so, iron as a supplement should only be taken following an identified deficiency following lab testing of iron levels in the body.

But when supplementing or when focusing on eating foods containing high levels of iron, some people find their levels remain stubbornly low.

What can you do?

The most common cause of low iron, besides low dietary intake or blood loss, is poor gut health and poor absorption of iron from the gut. It’s not just how much iron we consume or supplement with, but how much is actually absorbed into the body!

Inflammation and the gut?

Low grade inflammation is associated with all chronic disease. It can have a wide variety of causes, such as infections, injury, poor diet or toxins, even stress! But one of the most common areas where inflammation starts is in the gut.

When there is inflammation (during infection or injury), the liver releases a regulatory molecule (hepcidin) which blocks the absorption of iron. In other words, inflammation blocks the absorption of iron from the gut.

You can read about how to reduce inflammation in our gut here. Inflammation in the small intestine in particular, often found with small intestine bacterial overgrowth (SIBO), is associated with poor absorption of nutrients such as B12, iron, and zinc from the gut.

It is important, therefore, to assess inflammation of the gut when reflecting on why iron supplementation may not be raising iron levels in the body. This focus on the underlying systems of the body is a cornerstone of what is know as Functional Medicine.

Low Stomach Acid

Low stomach acid (HCl) is an important causative factor of anemia due to iron deficiency. Gastric HCl is important for nonheme iron absorption (non-meat iron sources) as this requires an acidic environment which helps the liberation of iron from food. In this article you can find out how to get an idea of your stomach acid levels with an east to do, at home, test.


Phytate is found in foods like whole grains, cereals, soy, nuts and legumes. It binds to minerals such as iron and zinc, preventing their absorption.

While eating some phytates is fine, many of us are eating more than the recommended amount, even those eating a Paleo diet containing a moderate amount of nuts.

But the research has shown eating even a small amount of phytate, at the same time as the source of iron, can decrease iron absorption. This inhibitory effect increases as the quantity of phytates increases. This is what is called a dose dependent effect. This effect can be counteracted by eating a source of Vitamin C at the same time.

Pair iron rich foods with Vitamin C

Iron from animal products, known as heme iron is the most easily absorbed by the body. But all is not lost if you are a vegetarian. Eating a source of Vitamin C along with plant base sources of non-heme iron helps absorption.

Foods high in vitamin C include citrus fruits, dark green leafy vegetables, bell peppers, melons and strawberries. In one study, 100mg of Vitamin C taken with food, increased absorption.

Iron and our Microbiome

Probiotics appear to increase the iron absorbing capability of the gut.

In particularly, a 2019 systematic review of the research found that the probiotic Lactobacillus plantarum 299v significantly increased iron absorption in humans.

Luckily for us, there are several commercially available probiotics containing this strain such as this one (affiliate link).

While we have discovered that some strains of probiotics increase iron absorption, other research is showing that other strains block absorption. And so to have optimal iron absorption from the gut, a balanced ecosystem of bacteria is needed. This means a healthy gut and microbiome!

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