A Simple, Affordable Fiber Supplement May Sharpen Your Brain — New Research Reveals Surprising Memory Boost for 60+

Researchers at King’s College London (KCL) recently published striking findings: a daily prebiotic fiber supplement — using commonly available plant-based fibers — improved cognitive performance in adults over 60 within just 12 weeks.

What the Study Did

The trial involved 36 pairs of twins — 72 participants total — all aged 60 or older, drawn from the large twin registry at KCL. King's College London
One twin from each pair received a daily prebiotic supplement (a mix of Inulin and Fructooligosaccharides (FOS) — 7.5 g total, delivering ~3.4 g inulin + ~3.5 g FOS). The other twin received a placebo. Nature Medical News Today
All participants also followed the same regimen of resistance exercise + a protein supplement, to test combined effects of protein, exercise, and prebiotic fiber on both muscle and brain health. Nature

✅ What the Study Found

After 12 weeks, those taking the prebiotic fiber showed significantly better performance on cognitive tests — including memory tests linked to early detection of Alzheimer’s (the “Paired Associates Learning” test), as well as improved reaction time and processing speed.
Stool-sample analysis revealed a notable increase in beneficial gut bacteria — especially Bifidobacterium — for the prebiotic group, underlining a change in gut microbiome composition.
Importantly: The supplement did not improve muscle strength or chair-rise time over the same period.

The study’s authors conclude that cheap, over-the-counter prebiotic fiber supplements may offer a safe, accessible way to support cognitive health in older adults — at least in the short term. King's College London

Why It Matters: Gut Health, Brain Health & the “Gut–Brain Axis”

The findings reinforce a growing body of research on the so-called gut–brain axis — the idea that the microbiome in your gut can influence your brain, cognition, and even mood.

By providing fermentable fibers (inulin / FOS), you can feed beneficial bacteria (like Bifidobacterium), which in turn produce metabolites (like short-chain fatty acids) that may support brain health, reduce inflammation, or influence neuro-chemical pathways. PMC

For older adults — many of whom experience age-related cognitive slowing — a** simple, low-cost strategy** like a daily fiber supplement might help maintain sharper memory and processing speed.

That said, the study authors themselves caution that this is an early, relatively small study; whether the benefits persist long-term, or apply to younger adults, remains to be seen.

Prebiotic Fiber Supplement

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What This Doesn’t Mean — And Proceed With Caution

The study was small (72 participants) and only lasted 12 weeks — not a guarantee of long-term brain health or dementia prevention.
The benefits were observed in older adults (60+), mostly drawn from a twin registry (which has its own sample biases), so might not apply to younger or more diverse populations. Nature+1
The prebiotic did not improve muscle strength in the study — so this is not a magic pill that reverses all aging-related decline. Nature+1
As always — gut-brain interactions are complex. Fiber alone isn’t a replacement for a balanced diet, exercise, mental activity, or medical care.