An inexpensive daily supplement appears to improve brain function in older adults

What’s good for your aging gut may also be good for your aging brain.

A first-of-its-kind study in twins has found that taking daily protein and prebiotic supplements can improve memory test scores in people over 60.

Published in 2024, the findings are food for thought, especially the same visual memory and learning test used to detect early signs of Alzheimer’s disease.

A double-blind trial tested two inexpensive plant fiber prebiotics that are available over the counter in many countries.

Prebiotics are non-digestible nutrients that help stimulate our gut microbes.

One of the supplements was inulin, a dietary fiber in the fructans class. Another, fructooligosaccharide (FOS), is a plant carbohydrate that is often used as a natural low-calorie sweetener.

Watch the video below for a summary of the research:

To see how these supplements affect aging brains, researchers at King’s College London matched 36 pairs of twins, all at least 60 years old.

Each pair was randomly assigned: one received a twice-daily prebiotic mixed with protein powder, while the other received a placebo powder.

Twins who inadvertently received inulin or FOS generally scored higher on cognitive tests three months later.

What’s more, daily fiber supplements were associated with subtle changes in the gut microbiome between twins.

useful BifidobacteriumFor example, it was more common in people taking insulin or FOS.

Studies in mice suggest this Bifidobacterium Reduces cognitive deficits by regulating gut-brain communication.

Mary Né Lochlin, a genetic medicine researcher at King’s College London, said: “We are excited to see these changes in just 12 weeks. This holds great promise for improving brain health and memory in our older population.”

“Unraveling the secrets of the gut-brain axis could offer new ways to live a healthy life long-term.”

King’s College is home to the UK’s largest adult twin registry, and twin studies are invaluable when it comes to distinguishing between genetic and environmental influences on human health.

Previous studies in mice suggest that high-fibre supplements, such as inulin and FOS, can feed the gut microbiome, allowing ‘good’ bacteria to thrive.

Some of these bacterial players have also been linked to improved cognitive performance in both mice and humans.

Evidence of the intimate relationship between the gut and the brain grows year by year. Some experts are now so convinced of the results, they refer to the gut as the body’s second brain.

But the way these two nervous systems work together remains a mystery.

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A two-part study at KCL points out that consuming certain ‘brain foods’ could be a promising way to treat cognitive decline, and research suggests that key nutrients can slow its progression.

“These plant fibers, which are cheap and available over the counter, can benefit a wide range of people at a time of cash. They are safe and acceptable.”

“Our next task is to see if these effects persist over a longer period of time and in larger groups of people.”

While prebiotics improve some aspects of cognitive function in the aging brain, such as memory and processing times, studies have not identified significant physical benefits.

Taking high-fiber supplements did not improve muscle loss among older children, although inulin and FOS were important muscle-protecting factors.

The couples who participated in the current trial were mostly female, and although the researchers adjusted for gender differences in their findings, they acknowledge that there may have been some selection bias between the KCL twin groups.

That said, women are more susceptible to Alzheimer’s disease, and studies like this one support the emerging idea that cognitive decline isn’t always a brain disease, but may involve external factors as well.

one last The Lancet The Dementia Commission estimates that 7 percent of Alzheimer’s risk is attributable to high median lifetime levels of low-density lipoprotein, which carries cholesterol and fatty acids around the body.

This risk factor may explain why women are twice as likely to develop Alzheimer’s as men, according to a 2025 study led by researchers at King’s College London.

Related: 117-Year-Old Woman’s Diet Could Help Us Live Longer

Also in 2025, researchers reported that in humans and mice, the ratio of low Bifidobacterium you Akramnesia Bacteria in the gut are linked to multiple sclerosis, and this imbalance is linked to many more serious diseases.

The gut has its fingers on many bodily ‘legs’, including the immune system and central nervous system. Feeding this microbiome certain prebiotics and probiotics can open the door to treating many diseases and ailments.

The study was published in 1993 Nature Communications.

An earlier version of this article was published in March 2024.