Are prebiotics good or bad in SIBO?

Since my previous blog about IBS and SIBO I have had so many questions from my patients wanting to know more about SIBO. What stands out to me the most is a confusion around what to eat, with the most common questions surrounding prebiotic, fibre rich foods and if they help or hinder SIBO.

 

What is a prebiotic food and what does our gut do to it?

A prebiotic is a non-digestible food ingredient that it is not broken down or absorbed in the higher parts of our gastrointestinal tract(1). There are a lot of foods with prebiotic properties including chickpeas, legumes, leeks, rye bread, garlic and cashews(2). They play a special role in our health - they act as food to our gut's good bacteria, increasing their numbers (lactobacilli and bifidobacteria(3)) and improving our overall health(1).  

 

Why do these healthy foods cause discomfort?

In SIBO, the overgrowth of bacteria causes inflammation and hurts your gut wall affecting your ability to breakdown and digest food. The bugs themselves play havoc with your own enzymes and body processes. For example there is loss/decrease in an enzyme called disaccharideses, which is important for breaking down carbohydrates and sugars. This means that any food, like a prebiotic food that contains fructose, lactose and sorbitol, may not be digested properly, resulting in those uncomfortable symptoms you experience(4).

 

Treating SIBO… with prebiotics?!

You may notice that some of the foods that cause your discomfort are also considered to be high FODMAP foods. FODMAP describes a group of of short-chain carbohydrates and sugar alcohols comprising of fructose, lactose, fructo- and galactooligosaccharides (fructans, and galactans), and polyols(5).

To provide symptom relief from SIBO we may suggest avoiding these high FODMAP prebiotics foods (looking at you apples, onions and garlic!) for a short period of time. It is really important to know that excluding these foods long term is not the answer and will not fix SIBO(6). A healthy gut is dependant on you eating a fibre rich, highly diversified diet so restricting these foods for a long period of time will only worsen your situation and increase your sensitivity to more foods(7). It's not uncommon that we see patients tolerating only a handful of foods and it's best to avoid this! 

Garlic, a wonderful prebiotic food.

Garlic, a wonderful prebiotic food.

As part of our treatment for SIBO we use certain types of prebiotics in combination with probiotics and specific antimicrobials (bug killers). These types of prebiotics have beneficial roles in our gut health that are important for restoring your gut health.

The following are four common prebiotic supplements on the market, three of which we use regularly in the treatment of SIBO. The fourth is not advised!

1. Lactulose

Lactulose is made up of two sugars, galactose and fructose, which is not broken down or absorbed in our small intestine. Lactulose increases our good bugs like bifidobacteria(8) and decreases the bad ones like clostridia(9). It is generally well tolerated, however you can take too much of it and end up with loose bowels(8)

2. Partically Hydrolysed Guar Gum (PHGG)

PHGG is a natural water soluble fibre that has been broken down by an enzyme to make it smaller and to decrease the amount of galactomannon (10). PHGG increases the good bugs Bifidobacterium and Lactobacillus species and decreases nasty waste products such as ammonia(11). PHGG can also give softer stools to assist constipation(12). Studies also show that PHGG in combination with an antibiotic to treat SIBO was more useful in eradicating SIBO compared with the antibiotics alone(13), how amazing!

3. Galacto-oligosaccarrides (GOS)

GOS is formed by breaking down lactose, a common sugar found in dairy. GOS is known to increase the good bugs bifidobacteria and reduce the bad bugs, clostridia and bacteroides. Another benefit of GOS alone or in combination with a probiotic is that it can support our immune system. GOS used in its recommended dosage range is well tolerated. Again, too much of a good thing can lead to problems; abdominal discomfort, cramping, flatulence and diarrhoea(14)

4. Inulin

Inulin is beneficial to out gut because it supports our good bugs bifidobacteria. However, because it is made up fructans(15), it can be really uncomfortable to consume if you have SIBO. Studies have found inulin increases flatulence, rumbling, stomach and gut cramps, and bloating(16). So best to avoid this one! 

Take home messages

Prebiotics are very powerful and beneficial for SIBO. But remember, not all prebiotics are the same.

If certain foods are causing you pain, bloating, constipation, or diarrhoea, this is your body communicating to you that your digestion system is struggling. Ironically the foods that cause discomfort are the same foods that are important to your health. Instead of excluding these foods, we need to improve your digestive system so you can tolerate these and improve your health in the long run. This can be impossible to navigate by yourself so get a professional on board to help correct your bugs, restore your gut wall and find the diet and fibre that is right for you.

After this, you may even be able to handle eating delicious lentils, onion, garlic and apples!

By Rachel Larsson

BHSc (Naturopathy), BPH (Nutrition)