What’s Beneficial for Your Gut Might Help Your Brain Too

A new study suggests that what’s good for an aging gut could also aid an aging brain. This research, unique in its design involving twins, indicates that daily protein and prebiotic supplements can enhance memory test results in individuals over 60.

Released in 2024, the study brings attention to its implications, especially since the same memory tests are used to identify early signs of Alzheimer’s disease.

The double-blind study examined two readily available plant-fiber prebiotics. These prebiotics are non-digestible substances that promote the growth of gut microbes. One of the supplements tested was inulin, a fiber from the fructan category, while the other was fructooligosaccharide (FOS), a plant carbohydrate often used as a low-calorie sweetener.

To investigate how these supplements impact the aging brain, researchers from King’s College London enlisted 36 pairs of twins, all aged 60 and above. Each twin pair was randomly assigned, with one receiving a daily prebiotic mixed into protein powder, and the other receiving a placebo.

Interestingly, those twins who unknowingly consumed either inulin or FOS generally performed better on cognitive tests three months later. Additionally, there were slight changes observed in the gut microbiome of the twins who took the supplements.

The beneficial bacteria strains, such as Bifidobacterium, were found in greater numbers among those taking the prebiotics. Research in mice suggests that Bifidobacterium helps reduce cognitive deficits through its regulation of gut-brain connections.

Mary Ni Lochlainn, a researcher at King’s College, expressed excitement about the findings: “We are thrilled to witness these changes in just 12 weeks. It shows great potential for improving brain health and memory in older adults.” She added that understanding the gut-brain axis may lead to new strategies for healthier aging.

King’s College boasts the UK’s largest adult twin registry, making twin studies invaluable for assessing the relative impacts of genetics and environment on health outcomes.

Previous animal research has indicated that high-fiber supplements, like inulin and FOS, nourish the colon’s microbiome, promoting the growth of beneficial bacteria. Some of these bacteria have also shown connections to improved cognitive functions in both rodents and humans.

The association between gut health and brain health is growing increasingly evident. Some experts have even begun referring to the gut as the body’s “second brain.” Yet, the precise mechanism linking the two remains elusive.

This twin study hints at the possibility of incorporating certain ‘brain foods‘ in strategies aimed at treating cognitive decline, aligning with findings that key nutrients could potentially slow brain aging.

Claire Steves, a geriatrician at KCL, pointed out, “These inexpensive plant fibers could be beneficial for many, especially in times of financial constraint. They are also safe for most individuals.” She noted that future research will aim to determine if these benefits can be sustained over a longer duration and across broader populations.

While prebiotics seemed to enhance some cognitive functions in aging brains, such as memory and processing times, the study did not show significant physical benefits. For example, muscle loss did not improve among the aging twins, even though inulin and FOS are critical for maintaining musculoskeletal health.

It’s worth noting that the twins involved in the study were largely female, raising potential concerns about selection bias. Even though adjustments were made for any sex differences, it’s acknowledged that females have a higher risk of developing Alzheimer’s. This study supports the idea that cognitive decline may not solely stem from brain pathology but could also be influenced by various external factors.

A recent Lancet Commission for Dementia estimated that 7 percent of Alzheimer’s risk can be linked to elevated midlife low-density lipoprotein levels, which transport cholesterol and fatty acids throughout the body. This finding might help explain why Alzheimer’s diagnoses are more prevalent in women.

The gut’s role in influencing various bodily processes is becoming clearer, with research suggesting improving its microbiome through certain prebiotics and probiotics could contribute to better management of many health conditions.

This study was published in Nature Communications.