Brains of Older Adults Boosted in Just 12 Weeks by Daily Fiber Supplement

Scientists have revealed a simple daily supplement that has been shown to improve brain function in older adults in as little as 12 weeks. The problem is, 95 percent of Americans are not eating enough of this essential nutrient.

Fiber is a type of tough carbohydrate that our bodies can't digest. Unlike other carbohydrates, which are broken down into simple sugars, fiber passes through the gut largely undigested. This helps regulate our blood sugar levels, keeps our hunger in check, and supports the flow of material through the intestines.

But fiber's roles extend beyond digestion. Numerous studies have found that high fiber diets are associated with a lower risk of developing heart disease and diabetes, and also appears to support out gut microbiome, with subsequent reductions in chronic inflammation. Indeed, high fiber diets may even have a protective effect against certain types of cancer.

Now, according to new research from King's College London, fiber might also play an important role in supporting brain function in older adults. In a study published in the journal Nature Communications, the team recruited 36 pairs of twins—72 individuals in total—over the age of 60. Each twin received either a placebo or a 7.5-gram fiber supplement every day for 12 weeks, although neither the participants nor the researchers knew who was receiving what.

Alongside this intervention, all participants also performed resistance exercises and ate a protein supplement daily.

After 12 weeks, the team saw that the fiber supplement had led to significant changes in the participants' gut microbiomes—the trillions of bacteria that live in our gut and play a role in everything from our digestion to our mental health. In particular, participants taking the supplement saw a significant increase in the number of beneficial bacteria, called Bifidobacteria, in their gut.

These changes were likely seen because of the prebiotic properties of fiber—that is, its ability to feed and support beneficial bacteria in our guts. But what does this have to do with our cognitive health?

Within just 12 weeks, participants receiving fiber supplements were performing better in tests assessing brain function, including the Paired Associates learning test which is a key assessment for early Alzheimer's.

Exactly what causes these improvements is unclear, but the researchers believe it may have something to do with the gut-brain axis, a bi-directional highway between our guts and our brain. Previous studies have demonstrated associations between prebiotics and mood improvements, as well as memory and recognition.

"We are excited to see these changes in just 12 weeks," the study's first author, Mary Ni Lochlainn, from King's College London's Department of Twin Research, said in a statement. "This holds huge promise for enhancing brain health and memory in our ageing population. Unlocking the secrets of the gut-brain axis could offer new approaches for living more healthily for longer."

Senior author Clair Steves, a Professor in Ageing and Health at KCL, said that this intervention represented an accessible, affordable solution to supporting cognitive health in older adults.

"These plant fibres, which are cheap and available over-the counter, could benefit a wide group of people in these cash-strapped times," she said in a statement. "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."

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