Prebiotics are a type of dietary fibre that acts as fuel for the good bacteria in your gut. These beneficial bacteria help keep your digestive system healthy and play a role in immunity and overall health.

There are many different types of prebiotics, but the most common ones are inulin and oligosaccharides. Prebiotics are found in a variety of plant-based foods, including chicory root, Jerusalem artichoke, garlic, onion, bananas, and oats. You can also find prebiotic supplements in some health food stores.

While prebiotics are generally considered safe, it’s important to talk to your doctor before adding them to your diet if you have any underlying medical conditions. Some people may experience gas and bloating when they first start taking prebiotics, but these side effects usually go away after a few days.

If you’re looking to improve your gut health, adding prebiotics to your diet is a good place to start. Just be sure to eat a variety of other healthy foods as well, such as probiotics, fermented foods, and plenty of fruits and vegetables.

ACTIONS AND PHARMACOLOGY

Mechanism of Action

Prebiotics are nondigestible carbohydrates that serve as substrates for indigenous gut microbiota, providing a selective advantage for bacteria with the ability to break them down. This fermentation process results in short-chain fatty acids (SCFAs), including acetate, propionate, and butyrate, which have been shown to offer several health benefits. Additionally, prebiotics can stimulate growth of certain beneficial bacteria, such as Bifidobacterium and Lactobacillus species.

In vitro and animal studies have suggested that prebiotics may also help modulate immune responses. For instance, they may enhance production of regulatory T cells and reduce proinflammatory cytokine production.

Pharmacokinetics

Prebiotics are not absorbed and are fermented by gut microbiota. Fermentation of inulin results in the production of SCFAs, including acetate, propionate, and butyrate. Animal studies have shown that butyrate may be absorbed through the colonic mucosa and influence gene expression in peripheral tissues. In humans, peak concentrations of SCFAs produced after inulin ingestion have been observed 3 to 4 hours after consumption.

CLINICAL TRIALS

Research on prebiotics has mostly been conducted using inulin and oligofructose. A few clinical trials have looked at the effects of prebiotics on gut microbiota, immunity, and overall health.

Gut Microbiota

A small (N=20), randomized, double-blind, placebo-controlled trial examined the effects of inulin on gut microbiota in healthy adults.15 Participants were given either inulin or placebo for 4 weeks and then switched to the other treatment for another 4 weeks. The researchers found that inulin increased levels of Bifidobacterium and Lactobacillus species compared to placebo. Additionally, participants who received inulin had higher levels of SCFAs in their stool than those who received placebo.

In a similar trial, healthy adults were given either oligofructose or placebo for 6 weeks.16 This study found that oligofructose increased levels of Bifidobacterium and Lactobacillus species compared to placebo. Additionally, those who received oligofructose had higher levels of SCFAs in their stool than those who received placebo.

Immunity

In a small trial, healthy adults were given either inulin or placebo for 3 weeks.17 The researchers found that inulin enhanced production of regulatory T cells, which are a type of white blood cell that helps keep the immune system in balance. Additionally, those who received inulin had lower levels of proinflammatory cytokines in their blood compared to those who received placebo.

A similar trial looked at the effects of oligofructose on immunity in healthy adults.18 This study found that oligofructose enhanced production of regulatory T cells and reduced proinflammatory cytokine levels, similar to the effects seen with inulin.

AVAILABLE FORMS

Prebiotics are available in powder, capsule, and tablet forms.Some common prebiotic supplements include inulin, oligofructose-enriched inulin (OII), galacto-oligosaccharides (GOS), fructo-oligosaccharides (FOS), xylooligosaccharides (XOS), and transgalactooligosaccharides (TOS).

Prebiotics can also be found in some foods, such as Jerusalem artichoke, chicory root, onions, garlic, bananas, whole wheatbreads and cereals, honey, agave nectar, and yacon syrup.

Some foods, such as yogurt and kefir, also contain probiotics. Probiotics are live bacteria and yeasts that are beneficial for gut health. While prebiotics feed the good bacteria already in your gut, probiotics help to increase the number of good bacteria.

You can also find products that contain both prebiotics and probiotics, which are sometimes referred to as synbiotics. Synbiotic supplements typically contain a combination of inulin and Lactobacillus or Bifidobacterium species.

CONTRAINDICATIONS

People with the following conditions should speak to a healthcare provider before taking prebiotics:

Diverticulitis

Inflammatory bowel disease

Irritable bowel syndrome (IBS) – some case reports suggest that prebiotics may worsen symptoms; more research is needed to confirm this

Pregnancy or breastfeeding – not enough is known about the safety of prebiotics during pregnancy or breastfeeding; speak to a healthcare provider before taking any supplement if you are pregnant or breastfeeding

Prebiotic supplements should be used with caution in those who are at risk for gastrointestinal problems, such as diverticulitis or inflammatory bowel disease. Additionally, those with fructose intolerance or malabsorption should avoid prebiotics that contain high levels of fructose, such as fructo-oligosaccharides (FOS).Pregnant and breastfeeding women should consult a healthcare provider before taking prebiotics.

If you are considering taking prebiotics, speak to a healthcare provider to determine an appropriate dosage for you.

ADVERSE REACTIONS

The most common side effects of prebiotics are gas and bloating, which typically resolve within a few days with continued use. A few case reports have suggested that prebiotics may worsen irritable bowel syndrome (IBS) symptoms, but more research is needed to confirm this.

DOSAGE

There is no established dose of prebiotics. Clinical trials have used doses ranging from 2.5 to 30 grams per day, with the most common dose being 10 grams per day.

Supplements are typically taken with meals. If you are considering taking prebiotics, speak to a healthcare provider to determine an appropriate dosage for you.