Iron and Irritable Bowel Syndrome

Posted on May 27, 2024

Iron and Irritable Bowel Syndrome (IBS)

A key nutrient at risk when following a low FODMAP diet is iron. Iron plays an important role in the body as it is found in red blood cells, carrying oxygen from our lungs to the rest of our body.

There are two types of iron that exist: haem iron which comes from animal foods and non-haem iron found in mostly plant-based, non-animal sources. When following a low FODMAP diet, it’s important to not restrict any food group unnecessarily as this may likely lead to nutritional inadequacy (low nutrients in the body). Following a low FODMAP diet to ease symptoms associated with IBS does not require complete restriction of any of the five food groups (e.g. fruit, vegetables, grains, meat/alternatives and dairy/alternatives).

Iron deficiency occurs when your body doesn’t have enough iron to produce haemoglobin (a part of your red blood cells that gives blood its red colour and allows red blood cells to carry oxygenated blood throughout the body).
In general, great sources of iron such as meat are not limited on a low FODMAP diet. However, for people following a vegetarian/vegan diet alongside a low FODMAP diet, they may be at risk of iron deficiency. This is especially predominant if they are also avoiding large serves of legumes (a primary source of protein and iron for vegetarians/vegans). If this sounds similar to your diet, we recommend consulting with your doctor or dietitian.

What causes low iron?

Low iron consumption from diet such as following a vegetarian or vegan diet; a weight loss diet or a generally nutrient poor diet that does not include a large variety of foods or includes excess amounts of ultra-processed foods. Iron absorption issues can also occur from certain medical conditions such as Inflammatory bowel disease (IBD), bariatric surgery or untreated coeliac disease, or from medications such as proton pump inhibitors (PPI) which are a class of medications typically used to relieve symptoms of acid reflux, or gastroesophageal reflux disease (GERD).  Another cause for low iron can be if you’re losing blood through menstrual loss or donating blood for example.

Who is most at risk of low iron/ iron deficiency?

– A person not consuming enough iron in their diet or who does not absorb enough iron.
– People with a menstrual cycle.
– Pregnant women
– People avoiding certain food groups (e.g. animal products)
– People who have issues absorbing nutrients from food, such as those with untreated coeliac disease

Symptoms of low iron/ iron deficiency

Symptoms of low iron may include:
– Pale skin
– Fatigue
– Weakness
– Shortness of breath
– Headaches

Although these symptoms may indicate low iron; the only way to know for sure is through a blood test. Symptoms may vary depending on the individual but if you have any of these symptoms and you think you may have low iron, speak to your doctor about getting tested. It’s also important to be aware that the symptoms listed above may be linked to another medical condition or problem. Consult your doctor for advice if you have any of these symptoms.

What are some low FODMAP yet high iron food sources?

A diet high in lean meats, legumes, nuts/seeds, wholegrains, iron-fortified cereals and green leafy vegetables provide great sources of iron. Unfortunately, many of these foods may be limited or reduced when following a low FODMAP diet. However, with a good understanding of suitable low FODMAP portion sizes of these foods, you are likely to be able to consume adequate iron in your diet.

So, what are some suitable options?
Wholefoods such as meats, meat alternatives, grains and fortified options can be suitable on the low FODMAP diet.
What does fortified mean?
Certain cereals, bread, and other grain products have iron added to them during processing which makes them “fortified with iron.” This can be especially beneficial for individuals with dietary restrictions.

Low FODMAP iron options:
100g of spinach has 3mg of iron
100g of tempeh has has 3mg of iron
35g or 1 cup of fortified cereal such as FODMAP Friendly Kellogg’s Gluten Free Cornflakes has 3mg of iron
100g of firm tofu has 2.5mg of iron
30g or a small handful of pepitas have 2.5mg of iron
65g of cooked kangaroo has 2.5mg of iron
65g of cooked lean beef has 2mg of iron
60g of uncooked rolled oats have 2mg of iron
25mg or 1 slice of fortified bread has 2mg of iron
30g or a handful of peanuts have 1.5mg of iron
100g of tinned salmon has 1mg of iron
75g or 1/2 cup of legumes or lentils have 1mg of iron
20g or 4 squares of dark chocolate has 1mg of iron
100g or 5 florets of broccoli have 1mg of iron
100g or 1/2 a cup of quinoa has 1mg of iron
70g or 1 potato has 0.5mg of iron
40g or 1 egg has 0.5mg of iron

Tips and tricks to increase iron absorption

There are some foods and nutrients that can reduce the absorption of iron. These include tea, coffee and other foods that contain calcium, magnesium and zinc.
However, research has shown that taking vitamin C with iron can be beneficial. There have also been new studies showing that probiotics and vitamin A may also play an effective role.

The practical tips
– Try consuming foods high in vitamin C (e.g. citrus fruits, strawberries, kiwi fruit, capsicum) with your main meals which may help to increase the absorption of iron.
– Try to minimise having tea and coffee with your meals to ensure maximal iron absorption.
– Choose a variety of foods. Having balanced meals which contain both haem and non-haem sources of iron throughout the week can increase your iron.
– The addition of an iron supplement if recommended by your GP following blood test results. Speak to your GP if you’re concerned about your iron.

So, what is the main take home message?

While low iron or iron deficiency can occur in some people who have IBS, it can certainly be managed while following a low FODMAP diet. Many foods are low FODMAP and high in iron which can be regularly consumed with IBS and many strategies can be put in place to increase iron absorption and levels to prevent iron deficiency.
For additional help and support on this topic, be sure to consult an Accredited Practising Dietitian or your doctor.


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