Quick Facts

• Low to moderate glycemic index diets reduced Alzheimer’s disease risk by 16% in a 13-year study of over 200,000 adults
• High glycemic index diets increased dementia risk by 14% compared to low-glycemic eating patterns
• Participants who ate more low-glycemic foods like fruit, legumes, and whole grains showed notably lower cognitive decline risk

A massive 13-year study tracking over 200,000 UK adults has revealed that the type of carbohydrates people eat may significantly impact their dementia risk decades later.

Researchers from Spain’s Universitat Rovira i Virgili followed participants without dementia for an average of 13.25 years. During that time, 2,362 people developed dementia.

The study, published in the International Journal of Epidemiology, found that people eating low to moderate glycemic index diets had a 16% reduction in Alzheimer’s disease risk. Those consuming high glycemic index foods faced a 14% increase in dementia risk.

The Glycemic Index Connection

The glycemic index measures how quickly carbohydrate-containing foods raise blood glucose levels on a scale from 0 to 100. White bread and potatoes score high, causing rapid blood sugar spikes. Whole grains and most fruits score lower, leading to slower, steadier increases.

Study lead Mònica Bulló, professor at URV’s department of Biochemistry and Biotechnology, said the results indicate that following a diet rich in low-glycemic-index foods could decrease the risk of cognitive decline and dementia.

Participants who regularly ate low-glycemic foods like fruit, legumes, and whole grains showed a noticeably lower risk of Alzheimer’s disease compared to those favoring high-glycemic options.

How Carbs Affect Brain Health

Repeated blood sugar surges can promote inflammation, impair blood vessel health, and disrupt energy metabolism in the brain. These mechanisms are implicated in both Alzheimer’s and vascular dementia.

Because carbohydrates directly affect blood sugar and insulin levels, their quality can have major impacts on metabolic health and diseases linked to brain function. The brain relies on carbohydrates as a primary energy source, making steady glucose delivery crucial.

Research consistently shows that simple carbohydrates are associated with decreased cognition, while complex carbohydrates correlate with successful brain aging and improved memory.

Practical Applications

The study doesn’t suggest eliminating carbohydrates. Instead, it emphasizes choosing fiber-rich, minimally processed options that allow glucose to enter the bloodstream gradually.

Evidence-backed approaches include prioritizing whole, intact carbohydrates like beans, lentils, oats, and whole grains. Pairing carbohydrates with protein, fat, or fiber can also slow glucose absorption.

Carbohydrates make up about 55% of daily energy intake for most people, making this research particularly relevant for public health strategies. The findings suggest that carbohydrate quality is modifiable and could be an important step in reducing dementia risk.

Read more: Carbs For Brain Health? What 13 Years Of Research Just Uncovered