Gut Health FAQ: What Are Prebiotics?

Gut Health FAQ: What Are Prebiotics?
(Last Updated On: February 19, 2020)
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Happy Holidays everyone! I hope you got through Christmas without too many gut issues. But New Year’s is still to come. With that in mind, I’d like to shine a light on prebiotics. Because they can really help with maintaining a healthy gut and calming an irritated gut!

In the FAQ articles, I answer frequently asked questions from my dietitian practice. The question of today is, what are prebiotics?

You may have heard about PRObiotics, those are live bacteria that have a beneficial effect on the person taking them. If you want to read more about that, check my article on probiotics and antibiotics or my article on how to choose a probiotic supplement.

But PREbiotics may be new to you. So let’s start explaining!

Prebiotics gut health

What Are Prebiotics?

Prebiotics are present in foods. The prebiotics can not be broken down by the body and travel through the digestive tract unaffected. Once it gets to the large intestine, the gut bacteria that are present there start to break down (ferment) the prebiotics. This is a source of nutrition for them, and as a nice byproduct, they produce nutrients for you like vitamin K and Short Chain Fatty Acids (SCFA).

Prebiotics are beneficial for human health since they will stimulate the growth of the human’s gut bacteria by providing a source of nutrition for the beneficial bacteria living in your gut. If you want to read more about gut bacteria, click here for my article on how your gut bacteria can promote obesity.

As you can see in the figure below, prebiotics can have several names. They can come from dietary fiber, complex carbohydrates (oligosaccharides), phytochemicals and certain fatty acids.

What are probiotics
Figure from G. Gibson et al. ISAPP Consensus statement on the definition and scope on Prebiotics.

Criteria for Prebiotics

In order for something to be called a prebiotic, it has to meet certain criteria. As you can see in the figure below, the criteria are:
– Resistance to digestion in the upper parts of the digestive tract
– Fermentable by the gut bacteria
– Has beneficial effects on the human’s health
– Selective stimulation of growth of gut bacteria and probiotics (only the good ones may grow!)
– Stable in food processing. It can not get lost by cooking, cutting etc.

Prebiotic criteria
Figure from Markowiak et al. Effects of Probiotics, Prebiotics and Synbiotics on human health

Health Effects of Prebiotics

As mentioned above, the prebiotics need to have a beneficial effect on the human that takes them. The figure below shows what kind of beneficial effects have been described in research. First and foremost it is a beneficial effect in the gut microbiota by the growth of beneficial bacteria. Other effects are a reduction in the risk of getting colorectal cancer, support of the immune system, reduced risk of obesity and protection against infection.

Prebiotics effects
Figure from Markowiak et al. Effects of Probiotics, Prebiotics and Synbiotics on human health

Well, that makes it pretty clear that it’s important to consume prebiotics on a regular basis, doesn’t it? But the question remains, where do I find them?

Do you want more information on how to incorporate prebiotics in your food pattern? Schedule an online consultation at my online dietitian practice Darm diëtist, and I will help you with all your questions!

What Products Contain Prebiotics?

As mentioned above, prebiotics come from dietary fiber, complex carbohydrates (oligosaccharides), phytochemicals and certain fatty acids. A bunch of complicated names, that you usually won’t find on the nutritional label.

In some cases prebiotics are added to products, the most common one is formula for infants. You may have seen or heard that there is FOS and/or GOS in them. This is a chemically added prebiotic that resembles the Human Milk Oligosaccharides (HMO) that are naturally available in breast milk. HMO’s are beneficial and essential for the growth of the baby’s healthy gut bacteria. So formula tries to achieve the same effect with FOS and/or GOS. Of course, it’s not the same, but it’s better than nothing!

So it’s possible for prebiotics to have been added to products, but for now, I’d like to keep the attention to products that have naturally present prebiotics. Most studies that show a positive effect of prebiotics have been done with supplements, and getting a high amount of prebiotics from food would require you to eat a lot of prebiotic-rich foods. But every little bit will help!

Eating a lot of fiber-rich foods will generally help you get more prebiotics. Try to get an abundance of vegetables, fruits, whole-grains, nuts, and seeds. This will usually get you great support and nutrition for your gut bacteria.

There are some foods that are ‘famous’ for containing a lot of prebiotic properties. Prebiotics like inulin and oligofructose are found in onion, banana, artichokes, and garlic. The prebiotic GOS comes mostly from beans and legumes.

Resistant Starch

Another well known prebiotic is resistant starch. As the name suggests, the starch is resistant to digestion by the digestive tract. There are different types of resistant starch, some of them are naturally occurring in foods, while others are made by food processing.

Naturally occurring resistant starch is found in green bananas, lentils, brown rice, kidney beans, chickpeas, and potatoes.

Resistant starch is also formed when grain products like whole grain pasta, potatoes, and rice are cooked and then cooled again. Consuming the cooled product (preferably after approx. 24 hours of cooling) will provide you with high levels of resistant starch.

Prebiotics and FODMAP

On the FODMAP diet, it is wise to consume prebiotics, since the FODMAP diet is known for reducing the abundance of beneficial bacteria in your gut. Prebiotics can help to maintain your healthy gut bacteria while on the FODMAP diet.

Nonetheless, some prebiotics are high in FODMAPs. Namely the GOS and FOS (fructans and inulin) which are oligosaccharides. The oligosaccharides are a FODMAP group, so keep that in mind when following a prebiotic-rich FODMAP diet! As long as you keep to the recommended portion sizes for the products, it is smart to consume the prebiotic-rich products though!

Which prebiotic foods do you use on a regular basis? Let me know in a comment below!



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