Study finds daily fiber supplement improves older adults' brain function in just 12 weeks

by King's College London

Credit: Pixabay/CC0 Public Domain

A daily fiber supplement improved brain function in people over 60 in just 12 weeks. The study, published recently in Nature Communications by researchers from the School of Life Course & Population Sciences showed that this simple and cheap addition to diet can improve performance in memory tests associated with early signs of Alzheimer's disease.

11 april 2024--However, the prebiotic supplements inulin and FOS were found to have no effect on muscle strength over this period.

"We are excited to see these changes in just 12 weeks. This holds huge promise for enhancing brain health and memory in our aging population. Unlocking the secrets of the gut-brain axis could offer new approaches for living more healthily for longer," says first author Dr. Mary Ni Lochlainn from the Department of Twin Research.

As populations age globally, the prevalence of age-related conditions such as cognitive decline and muscle loss is on the rise. Researchers at TwinsUK, the U.K.'s largest adult twin registry based at King's College London, sought to understand how targeting the microbiota, the diverse community of microorganisms residing in our intestines, using two cheap, commercially available plant fiber supplements inulin and FOS, could impact both muscle health and brain function.

Researchers assigned 36 twin pairs—72 individuals—over 60 years old to receive either a placebo or the supplement every day for 12 weeks. Neither the analysis team, nor the participants knew which they received until the analysis was complete (double-blind). Alongside this, all study participants did resistance exercises and ate a protein supplement which was aimed at improving muscle function.

Researchers monitored participants remotely via video, online questionnaires and cognitive tests. They found the fiber supplement led to significant changes in the participants' gut microbiome composition, particularly an increase in the numbers of beneficial bacteria such as Bifidobacterium.

While there was no significant difference in muscle strength between the groups, the group receiving the fiber supplement performed better in tests assessing brain function, including the Paired Associates Learning test which is an early marker for Alzheimer's disease, together with tests of reaction time and processing speed. These measures are important for daily living—for example reacting to traffic or stopping a simple trip-up turning into a fall.

"These plant fibers, which are cheap and available over the counter, could benefit a wide group of people in these cash-strapped times. They are safe and acceptable too. Our next task is to see whether these effects are sustained over longer periods and in larger groups of people," says senior author Professor Claire Steves, professor of aging and health.

Another novel aspect of the study was its remote design which demonstrated the feasibility of conducting trials in older adults without the need for extensive travel or hospital visits, which could be delivered in many settings globally. Challenges such as digital literacy and access to the necessary technology were acknowledged and will be addressed in future larger scale projects with the aim to enhance the quality of life for aging populations worldwide.

More information: Mary Ni Lochlainn et al, Effect of gut microbiome modulation on muscle function and cognition: the PROMOTe randomised controlled trial, Nature Communications (2024). DOI: 10.1038/s41467-024-46116-y

Fiber intake associated with reduced risk of death

Dietary fiber may be associated with a reduced risk of death from cardiovascular, infectious and respiratory diseases, as well as a reduced risk of death from any cause over a nine-year period, according to a report posted online today that will be published in the June 14 print issue of Archives of Internal Medicine.

15 feb 2011--Fiber, the edible part of plants that resist digestion, has been hypothesized to lower risks of heart disease, some cancers, diabetes and obesity, according to background information in the article. It is known to assist with bowel movements, reduce blood cholesterol levels, improve blood glucose levels, lower blood pressure, promote weight loss and reduce inflammation and bind to potential cancer-causing agents to increase the likelihood they will be excreted by the body.

Yikyung Park, Sc.D., of the National Cancer Institute, Rockville, Md., and colleagues analyzed data from 219,123 men and 168,999 women in the National Institutes of Health-AARP Diet and Health Study. Participants completed a food frequency questionnaire at the beginning of the study in 1995 and 1996. Causes of death were determined by linking study records to national registries.

Participants' fiber intake ranged from 13 to 29 grams per day in men and from 11 to 26 grams per day in women. Over an average of nine years of follow-up, 20,126 men and 11,330 women died. Fiber intake was associated with a significantly decreased risk of total death in both men and women—the one-fifth of men and women consuming the most fiber (29.4 grams per day for men and 25.8 grams for women) were 22 percent less likely to die than those consuming the least (12.6 grams per day for men and 10.8 grams for women).

The risk of cardiovascular, infectious and respiratory diseases was reduced by 24 percent to 56 percent in men and 34 percent to 59 percent in women with high fiber intakes. Dietary fiber from grains, but not from other sources such as fruits, was associated with reduced risks of total, cardiovascular, cancer and respiratory disease deaths in men and women.

"The findings remained robust when we corrected for dietary intake measurement error using calibration study data; in fact, the association was even stronger with measurement error correction," the authors write.

"The current Dietary Guidelines for Americans recommend choosing fiber-rich fruits, vegetables and whole grains frequently and consuming 14 grams per 1,000 calories of dietary fiber," the authors conclude. "A diet rich in dietary fiber from whole plant foods may provide significant health benefits."

More information: Arch Intern Med. Published online February 14, 2011. doi:10.1001/archinternmed.2011.18