Quality and Quantity of Carbs Matter in Dementia Risk
Carbs have often been demonized by everyone from fitness gurus to functional nutrition professionals. In reality, we need some carbohydrates to fuel our bodies and brains, but obviously, the type and amount matter.
A recent, long-term study found that eating a diet high in fast-acting carbs that quickly increase blood sugar was associated with a higher risk of dementia. Subjects who consumed more low-glycemic foods, like beans, fruit, and whole grains had a significantly lower risk for Alzheimer’s. The type and quality of carbs, and not just how much is consumed, are important for brain health.
Diets designed around slow-digesting carbs were found to be associated with a reduced risk of dementia, while carbs that spiked blood sugar increased the risk. Eating whole grains, fruit, and legumes may protect the brain against dementia over time.
A study done by the Nutrition and Metabolic Health (NuMeH) research group at the Universitat Rovira i Virgili (URV), the Centre for Environmental, Food and Toxicological Technology (TecnATox), and the Pere Virgili Health Research Institute (IISPV), suggests that the type and amount of carbohydrates that people consume may significantly impact their risk of dementia development. The study was published in the scientific journal International Journal of Epidemiology.
We can’t stop aging, which is the most significant risk factor for dementia, though scientists note that lifestyle choices also have an important role. A nutritious diet can help support healthy aging and slow cognitive decline. Carbohydrates comprise over 50% of daily calorie intake. As carbs directly impact blood sugar and insulin levels, the quantity and quality can have a huge effect on metabolic health and conditions linked to brain function, such as Alzheimer’s.
Why the Type of Carbs Matters
The glycemic index (GI), a measure of how fast foods containing carbs raise blood sugar after eating, was the main focus of the study. The GI scale, ranges from 0 to 100, ranks foods based on their blood sugar response. Foods like white bread and potatoes score high, meaning they cause rapid blood sugar spikes, while whole grains, legumes, and most fruits score lower and produce slower rises in blood sugar.
To evaluate long-term effects, researchers reviewed data from over 200,000 adults in the UK who didn’t have dementia at the start of the study. Subjects completed detailed questionnaires, which allowed researchers to measure the glycemic index and load of their typical diets. During an average follow-up time of 13.25 years, 2, 362 subjects were diagnosed with dementia.
With modern statistical methods, the researchers discovered the point where higher nutritional glycemic index values were associated with higher dementia risk. This method helped distinguish how long-term eating habits could impact brain health later in life.
Less Risk with Lower Glycemic Diets
The research uncovered a clear pattern.
The analysis revealed a clear pattern. Eating patterns that included lower glycemic index foods were linked with a reduced chance of developing dementia, while higher GI diets were associated with a larger risk. In those whose diets were considered in the low to moderate glycemic range, a 16% lower risk of developing Alzheimer’s was observed. Conversely, diets with higher glycemic values were linked with a 14% increased risk.
Study leader Mònica Bulló, a professor in the URV's Department of Biochemistry and Biotechnology, a researcher at ICREA, and director of the URV's TechnATox Centre, noted, “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 and other types of dementia”.
Conclusions for Dementia Prevention
The results of this study aren’t surprising. It’s not just the amount of carbohydrates you eat, but the type that matters. Evaluating carbohydrate quality may be an important way to reduce dementia risk and promote long-term brain health.
Below are tips to reduce the glycemic index of your food:
1. Choose whole grains over refined when possible. These include brown rice, whole grain breads and cereals, and ancient grains such as bulgur, farro, and quinoa.
2. Enjoy berries regularly, which are a low-glycemic index fruit that are rich in antioxidants.
3. Add beans or lentils to soups, salads, or as a side. Go for three (1/2 cup) servings per week or more.
4. Limit highly processed snacks and desserts like chips, pretzels, cookies, and snack cakes.
5. Avoid sugar-sweetened beverages, including soda, sports drinks, and sweet tea.
6. Choose whole fruit over fruit juice for more fiber.
7. Include leafy greens in your diet regularly. As part of the MIND diet, these may help reduce the risk of dementia. 2
8. Enjoy dark chocolate (in moderation) over milk chocolate. It’s lower in sugar and fat.
9. Have nuts for a snack in place of chips. They’re full of healthy fats and lower in sugar.
10. Limit alcohol intake. Alcohol contributes nothing nutritionally to your diet and may increase the risk of dementia. 3
Lisa Andrews, MEd, RD, LD
References:
Nil Novau-Ferré, Javier Mateu-Fabregat, Christos K Papagiannopoulos, Christos V Chalitsios, Laura Panisello, Georgios Markozannes, Konstantinos K Tsilidis, Mònica Bulló, Christopher Papandreou. Glycemic index, glycemic load, and risk of dementia: a prospective analysis within the UK Biobank cohort. International Journal of Epidemiology, 2025; 54 (6) DOI: 10.1093/ije/dyaf182
Halloway S, Aggarwal NT, Arfanakis K, Sacks FM, Barnes LL, Dhana K. Effect modifiers of the MIND diet for cognition in older adults: The MIND diet trial. Alzheimers Dement. 2025 Oct;21(10):e70731. doi: 10.1002/alz.70731. PMID: 41058007; PMCID: PMC12504047.
Zahr NM. Alcohol Use Disorder and Dementia: A Review. Alcohol Res. 2024 May 23;44(1):03. doi: 10.35946/arcr.v44.1.03. PMID: 38812709; PMCID: PMC11135165.