Poor carbohydrate quality may increase dementia and Alzheimer’s disease risk

New research suggests that the quality and quantity of dietary carbohydrates have a significant impact on dementia development.

The Nutrition and Metabolic Health research group carried out a study on over 200,000 adults in the UK. Although the correlative study cannot confirm causality, it revealed that lower glycemic index (GI) foods were associated with a reduced dementia risk. Conversely, higher GI foods were linked to an increased risk.

Meanwhile, a low to moderate GI diet was linked to a 16% reduction in Alzheimer’s disease risk. However, high GI diets raise this risk by 14%.

The study in the International Journal of Epidemiology underscores the importance of choosing high-quality carbohydrates as part of dementia strategies.

Diet impacts aging

Age is a major risk and known factor for developing dementia, and maintaining a healthy diet and lifestyle can lower the risk, suggest the researchers. Healthy and balanced diets are beneficial for cognition and can promote healthy aging. 

They point out that carbohydrates are a major part of daily diets, making up 55% of the total energy consumed. Since they influence glucose and insulin metabolism, carbohydrates impact metabolic health and risk of related diseases.

In active aging solutions, dairy ingredients, such as collagen-rich and hydrolyzed proteins, are gaining attention for their ability to support muscle, bone, and joint health.

The researchers explain that GI is used to measure how fast carbohydrates spike blood glucose after consumption. For instance, white bread has a high GI, and most fruits and whole grains have a low GI.

Data analysis

The researchers examined data from a study involving over 200,000 UK adults who did not have dementia at the start of the process. Using questionnaires, they assessed the GI and glycemic load of each person’s diet.

After a follow-up period of 13.25 years, 2,362 people developed dementia. Using statistical techniques, the researchers identified the level of GI at which the risk of developing dementia began to increase.  

“These results indicate that following a diet rich in low-glycemic-index foods, such as fruit, legumes, or whole grains, could decrease the risk of cognitive decline, Alzheimer’s disease, and other types of dementia,” confirms the study lead, Mònica Bulló. She is a professor in the Universitat Rovira i Virgili’s (URV) department of Biochemistry and Biotechnology, a researcher at the Catalan Institution for Research and Advanced Studies, and the director of the URV’s TechnATox Centre, Spain.

The research team consisted of individuals from the Pere Virgili Health Research Institute.

Carbohydrate quality and dementia research

A recent study affirms that dietary carbohydrate quality is a promising factor, particularly in promoting healthy aging in women. This positive association challenges the idea that all dietary carbohydrates are negatively associated with chronic disease risk and all-cause mortality. The study’s co-author told Nutrition Insight how important carbohydrates are for older adults.

Another paper revealed that a person’s metabolic health determines how blood sugar responds to certain carbohydrates. Researchers at Stanford Medicine, US, suggested creating personalized prevention treatment strategies for prediabetes and diabetes based on a patient’s blood sugar response patterns.

In other previous research exploring dietary effects on dementia risks, scientists did not find any evidence that calcium increases the long-term risk of dementia in older women. This debunks previous theories that the mineral supplements could impact cognitive health.

However, any amount of alcohol consumption was found to raise dementia risk, challenging the previously held beliefs on the benefits of light drinking, according to one trial September 2025. Meanwhile, a separate study revealed that eating processed red meat was linked to an increased risk of dementia and cognitive decline compared with people who eat very little meat.