When you hear the word probiotics, you may think of the “good bacteria” living in your gut.
Probiotics are more specifically defined as live microorganisms that, when consumed in adequate amounts, provide a health benefit. Different probiotic strains can have different effects, which means we can’t assume that every probiotic provides the same health benefits.
There is also an important distinction between probiotic foods and fermented foods that simply contain live microorganisms. Some fermented foods may contain potentially beneficial bacteria, but this does not automatically mean they meet the scientific definition of a probiotic.
So, what does this have to do with iron?
Why Is Iron Important?
Iron is an essential mineral that your body needs to transport oxygen around the body.
It also has important roles in:
- Energy production
- DNA synthesis
- Normal immune function
- Cognitive function
- Red blood cell production
Getting enough iron from your diet is important, but how much iron your body absorbs is just as important as how much iron you consume.
Iron absorption is influenced by many factors, including the type of iron in your food, what you eat alongside it, and your body’s current iron status.
And this is where the gut microbiome becomes an interesting area of research.
Can Gut Bacteria Influence Iron Absorption?
Research is investigating whether certain microorganisms in the gut can influence how the body absorbs and uses iron.
Some studies have focused on bacteria from groups such as Lactobacillus and Bifidobacterium.
However, it is important to remember that these are broad bacterial groups containing many different strains. The effects of one strain cannot automatically be applied to every Lactobacillus or Bifidobacterium strain.
Researchers believe that gut microorganisms may influence iron availability through several mechanisms, including the production of short-chain fatty acids when certain types of dietary fibre are fermented by gut bacteria.
These compounds can influence the gut environment and may affect the availability and absorption of minerals such as iron.
However, research into probiotics and iron absorption is still developing, and probiotics should not be considered a proven treatment for iron deficiency.
What Does the Research Show?
One interesting study investigated whether a specific probiotic could influence iron absorption.
Researchers studied the probiotic strain Lactobacillus plantarum 299v (Lp299v) in people consuming an iron-fortified drink.
The study found that iron absorption was higher when the drink was consumed with Lp299v, with an increase of approximately 50% compared with the control condition.
This is an interesting finding — but there is an important qualification.
It does not mean that eating probiotic foods generally increases iron absorption by 50%.
The study investigated a specific probiotic strain, in a specific population, alongside a specific iron-fortified drink.
This is a good example of why we need to look at the evidence for individual probiotic strains rather than assuming all probiotics have the same effect.
What About Prebiotics?
Prebiotics are another important part of the conversation.
A prebiotic is a substrate that is selectively utilised by microorganisms and provides a health benefit.
Certain types of dietary fibre can be fermented by gut microorganisms, producing short-chain fatty acids and other compounds.
Examples of foods that contain prebiotic fibres include:
- Legumes such as chickpeas, lentils and beans
- Onions and garlic
- Some wholegrains
- Asparagus
- Green peas
- Certain fruits and vegetables
It is worth noting that not every food containing fibre is technically a prebiotic, and not every fibre has the same effect on the gut microbiome.
Rather than focusing on one particular prebiotic, a practical approach is to include a variety of fibre-rich plant foods throughout the week.
What About Fermented Foods?
Fermented foods can be a delicious way to add variety to your diet.
Depending on how they are produced and processed, some fermented foods may contain live microorganisms.
Examples include:
- Yoghurt containing live cultures
- Kefir
- Some traditionally fermented vegetables, such as sauerkraut and kimchi
- Tempeh
- Some fermented soy products
However, not every fermented food contains probiotics, and the microorganisms present can vary between products.
For example, kimchi may contain live lactic acid bacteria, but it is more accurate to describe it as a fermented food containing live microorganisms unless the specific product and microorganisms meet the criteria for a probiotic.
The same applies to foods such as miso and kombucha.
Should You Eat Two Probiotic Foods Every Day?
Rather than setting a strict goal of two “probiotic foods” every day, I prefer a more flexible food-first approach.
If you enjoy foods such as yoghurt with live cultures or kefir, these can be included regularly as part of a balanced diet.
You can also include a variety of plant foods to provide different types of dietary fibre that support your gut microorganisms.
Think about:
Variety + fibre + fermented foods you enjoy = a practical approach to supporting gut health.
There is no need to eat particular fermented foods if you don’t enjoy them.
What Can You Do to Support Iron Absorption?
If you’re interested in improving your iron intake and absorption, there are several well-established nutrition strategies that are more important than focusing specifically on probiotics.
Include iron-rich foods
Examples include:
- Lean red meat
- Chicken and other poultry
- Fish and seafood
- Eggs
- Legumes
- Tofu and other soy foods
- Iron-fortified cereals and breads
- Nuts and seeds
Include vitamin C with plant sources of iron
Vitamin C can increase the absorption of non-haem iron, the form of iron found predominantly in plant foods.
For example, you could combine:
- Lentils with capsicum
- Chickpeas with tomato
- Iron-fortified cereal with berries or kiwi fruit
- Beans with vegetables
Consider the overall meal
Tea and coffee can reduce the absorption of non-haem iron when consumed around meals, so timing can be worth considering if iron intake or iron status is a concern.
Take Home Message
Your gut microbiome is an important area of nutrition research, and there is growing interest in how certain microorganisms may influence the absorption and use of nutrients such as iron.
However, not all probiotics are the same, and research involving one specific probiotic strain cannot automatically be applied to all probiotic foods or supplements.
Rather than focusing on a particular number of probiotic foods each day, take a food-first approach by eating a varied diet containing plenty of fibre-rich plant foods and including fermented foods that you enjoy.
And if you’re concerned about your iron intake or iron levels, speak with your GP or Accredited Practising Dietitian. Iron deficiency has many potential causes and may require assessment and individualised treatment.
Your gut health is important — but there is no single food, probiotic or supplement that provides everything your body needs. Variety is key.
References
[1] Skrypnik K, Suliburska J. Association between the gut microbiota and mineral metabolism. Journal of Trace Elements in Medicine and Biology. 2018.
[2] Hoppe M, Önning G, Berggren A, Hulthén L. Probiotic strain Lactobacillus plantarum 299v increases iron absorption from an iron-supplemented fruit drink: a randomised controlled trial. British Journal of Nutrition. 2015.
[3] Hill C, Guarner F, Reid G, et al. The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology & Hepatology. 2014;11:506–514.
[4] Gibson GR, Hutkins R, Sanders ME, et al. Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. 2017;14:491–502.
