Gut Microbiota, Prebiotics, Probiotics and GLP-1: What the Evidence Shows

March 22, 2024 Kasivit Editorial Team

Gut microbiota has been increasingly recognized to play a significant role in human health and disease by affecting the gastrointestinal tract's immune system, energy metabolism, and inflammatory responses. Recent research has explored links between the gut microbiota, oral prebiotics and probiotics, and glucagon-like peptide-1 (GLP-1) secretion. Much of this evidence is mechanistic.¹ Human trials of prebiotics and probiotics have so far shown limited effects on GLP-1 and on metabolic outcomes, as described below.

GLP-1 is a hormone produced by the intestine that stimulates the release of insulin and inhibits the release of glucagon, which helps to lower blood sugar levels. GLP-1 medications, also known as glucagon-like peptide-1 receptor agonists (e.g. Wegovy, Ozempic, Saxenda, Victoza, etc.), are medicines used to treat type 2 diabetes and, for some products, obesity. Most are given as an injection. In trials, these medicines have lowered blood sugar and produced weight loss, including in people without diabetes.² An oral semaglutide tablet also exists.³ GLP-1 agonists mimic the effects of the natural hormone GLP-1 in the body and stimulate the GLP-1 receptor. This leads to increased glucose-dependent insulin secretion, reduced glucagon secretion, slowed gastric emptying, and increased satiety.

This article aims to provide an overview of the relationship between oral prebiotics and probiotics and GLP-1 secretion and how it can impact on metabolic and gastrointestinal health.

The human gut is a bustling metropolis of microorganisms that play a crucial role in our overall health, particularly in metabolic diseases like obesity and type 2 diabetes (T2D).¹ Recent research has examined the intricate interplay between gut microbiota and the incretin glucagon-like peptide 1 (GLP-1), identifying potential pathways that are still being investigated.

Gut Microbiota: Our gut microbiota is tiny organisms inside us that do many important things for our bodies. They help with how our food is absorbed, how we digest fiber and break down bile acid. The gut microbiota can influence the secretion of a hormone called GLP-1, which helps control blood sugar after eating.¹ Whether this leads to weight loss in people has not been established (see below).

The GLP-1 Connection. GLP-1 affects more than just blood sugar and is involved in how the gut bacteria works. Differences in gut bacteria have been observed in people with obesity and type 2 diabetes; whether they cause these conditions has not been shown.¹ GLP-1 drugs have been successful in treating T2D & obesity and show how important GLP-1 is.

Microbiota and Metabolites: A Symbiotic Relationship The microorganisms in our gut have a close relationship with the metabolites they produce. These metabolites can control the behavior of some cells, known as enteroendocrine cells, and affect hormone production and release. Some of these metabolites, like SCFAs and BAs, can induce the secretion of a hormone called GLP-1. This has led researchers to study prebiotics and probiotics in obesity and type 2 diabetes. So far, human trials show at most modest effects. In a 2026 meta-analysis of more than 30 trials, probiotics lowered HbA1c by about 0.21 percentage points compared with placebo, which the authors called statistically significant but clinically modest, with substantial variability between studies.⁴ A 2026 meta-analysis of 10 trials found no significant effect of probiotics or synbiotics on body weight, and the authors described the findings as preliminary.⁵ In a randomized crossover trial of 29 people with type 2 diabetes, 16 g/day of a prebiotic (inulin-type fructan) for 6 weeks did not improve the GLP-1 response to a meal.⁶

The Future of Treatment: Personalized and Precise As we study the relationship between the bacteria in our gut and GLP-1, a hormone that helps regulate blood sugar levels, researchers are exploring whether customized approaches could help manage metabolic diseases; this remains a research question rather than an established treatment. Bariatric surgery and some diabetes medicines have been reported to affect the interaction between gut microbiota and GLP-1,¹ but whether adjusting the microbiota can itself improve metabolic health in people is still being studied. For this reason the gut microbiota is being investigated as a possible target in metabolic disease.¹

Closing Thoughts. The relationship between the gut microbiome and GLP-1 is an active area of research. Current evidence that prebiotic or probiotic supplements change GLP-1 or metabolic outcomes in people is limited, and supplements are not a substitute for prescribed treatment. With more research and advancements in technology, it opens up new opportunities for precision medicine where the gut microbiome is not only involved in our health but also becomes a target for treatment.

Kasivit's Gut Support Bundle is not a treatment for obesity or type 2 diabetes and does not replace prescribed medicines. If you take a GLP-1 medicine, insulin or another glucose-lowering medicine, ask your prescriber or pharmacist before adding any supplement.

Safety note. This article is general information and not medical advice. Probiotics are generally well tolerated by healthy adults, but they are not suitable for everyone. In a trial of 298 people with predicted severe acute pancreatitis, a multispecies probiotic was associated with higher mortality (16% vs 6%), and the authors advised against its use in that group.⁷ A 2026 review concluded that the evidence does not permit conclusions about long-term safety of probiotics in at-risk groups such as older, immunocompromised and gastrointestinal patients.⁸ People with a weakened immune system, a central venous catheter, a serious illness or a serious bowel condition, and people who are pregnant or breastfeeding, should talk to a doctor before taking a probiotic or prebiotic supplement. Supplements do not replace GLP-1 medicines, insulin or other diabetes or weight-management treatment. Do not change prescribed medicines on the basis of this article; ask your prescriber or pharmacist.

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