Small intestinal bacterial overgrowth (SIBO) affects millions of people, but most are never diagnosed. When you have gut discomfort, bloating, or food sensitivities, standard probiotics may not be the answer — in some cases they may make things worse.

Small intestinal bacterial overgrowth (SIBO) affects millions of people, but most are never diagnosed. When you have gut discomfort, bloating, or food sensitivities, standard probiotics may not be the answer — in some cases they may make things worse.

What SIBO Actually Is

SIBO occurs when there is an abnormally large population of bacteria in the small intestine. The small intestine typically has a relatively small bacterial population compared to the colon — numbering in the thousands versus the trillions. When you take probiotic supplements, you are introducing live microorganisms designed to colonise the gut.

The problem is that the bacteria colonising in SIBO ferment carbohydrates, producing hydrogen and methane gases. This causes bloating, pain, and — importantly — carbohydrate malabsorption. When carbohydrates are fermented by bacteria in the small intestine rather than digested, they are lost from the diet, contributing to nutritional deficiencies and symptoms.

Why Standard Probiotics Are Ineffective for SIBO

Most commercial probiotics contain Lactobacillus and Bifidobacterium strains. These bacteria perform well in the colon, where there is an anaerobic environment suited to them. In the small intestine, they face competition from overgrowth bacteria and the environment is less favourable to them.

Additionally, some probiotic supplements may contain fermenting bacterial strains, which could exacerbate SIBO-related symptoms. Adding more fermenting bacteria when fermentation is already excessive in the small intestine is unlikely to help.

The Gut-Brain Axis and SIBO

The gut communicates with the brain via the vagus nerve and neurotransmitters. Approximately 90% of the body’s serotonin is produced in the gut, a figure that underscores how profoundly gut function influences the central nervous system.

SIBO is closely associated with irritable bowel syndrome (IBS) symptoms, and IBS is linked to increased anxiety and depression. Gut-brain axis dysregulation is at the core of these associations.

The VisiFlora Approach

VisiFlora recognises that gut health is not simply a matter of probiotic quantity. It targets the gut-brain axis, supporting overall gut microbiome balance rather than simply adding specific strains. This approach is better suited to addressing functional gut issues.