Rice, roti, poha, upma — carbohydrates show up on almost every Indian plate, often more than once a day. New research is asking a question most of us have never stopped to consider: does it matter which carbs we choose, not just how many?

• A 13-year study of over 200,000 UK adults linked carbohydrate quality to dementia risk
• Diets rich in low-glycemic-index carbs were tied to a 16 percent lower risk of Alzheimer's disease
• Diets high in fast-digesting, high-glycemic-index carbs showed a 14 percent higher dementia risk
• Carbohydrates make up roughly 55 percent of daily calories for most people, so quality matters a lot
• Whole grains, legumes, and fruit were the foods most consistently linked to lower risk

Yes, the type of carbohydrate you eat appears to matter for brain health, not only how much you eat. A large study from researchers at Universitat Rovira i Virgili and the Pere Virgili Health Research Institute in Spain, published in the International Journal of Epidemiology, followed over 200,000 adults in the UK for an average of more than 13 years. None of them had dementia at the start. By the end of the study, 2,362 people had developed the condition. Adults whose diets leaned toward low-to-moderate glycemic-index carbohydrates — the ones that raise blood sugar slowly — had a 16 percent lower risk of developing Alzheimer's disease. Those who ate mostly high-glycemic-index carbohydrates, the fast-digesting kind, had a 14 percent higher risk of dementia overall. Carbohydrate quality, in other words, seems to be doing real work in protecting the aging brain.

What the Study Actually Measured

To understand the findings, it helps to know what glycemic index actually measures. It's a ranking of how quickly a carbohydrate-containing food raises blood sugar after you eat it — white bread and sugary cereals rank high, while lentils, oats, and most vegetables rank low. The Spanish research team used detailed dietary questionnaires to estimate both the glycemic index and glycemic load of each participant's diet, then tracked who went on to develop dementia over more than a decade. Study director Monica Bullo summed up the takeaway plainly: a diet rich in low-glycemic-index foods could decrease the risk of cognitive decline and dementia.

Why Fast Carbs May Be Hard on the Brain

The likely explanation lies in blood sugar and insulin. Carbohydrates make up about 55 percent of the average person's daily calories, so how the body handles them has an outsized effect on metabolic health. Foods that spike blood sugar repeatedly can, over years, push the body toward insulin resistance, a state where cells stop responding properly to insulin and blood sugar stays elevated. Insulin resistance is already linked to type 2 diabetes, and a growing body of research connects it to Alzheimer's disease too, partly because insulin also plays a role in how brain cells communicate and clear away waste proteins. Slow-digesting carbs avoid these repeated spikes, which may be why they showed up as protective in the study.

The Foods That Came Out Ahead

The researchers pointed to fruit, legumes, and whole grains as the low-glycemic-index foods worth building a diet around. What these foods tend to have in common is dietary fiber, which slows down digestion and blunts the blood sugar spike that refined, processed carbohydrates cause. This is also why whole, minimally processed grains behave so differently in the body compared to their refined counterparts, even when the calorie count looks similar on paper.

Traditional Indian Kitchens Already Had the Right Idea

Long before glycemic index became a research term, Indian kitchens were already leaning on low-glycemic staples — ragi, jowar, bajra, and a rotation of dals that digest slowly and keep blood sugar steadier through the day. Millets like ragi, or finger millet, have one of the lowest glycemic indices among Indian grains, which is part of why they quietly stayed a staple in traditional diets for generations, even as polished white rice and maida took over urban plates. This kind of small, low-effort dietary shift is exactly the sort of thing we explore in The Wellness Imperative — changes that compound over years rather than promising anything overnight.

If you're looking for a simple low-glycemic swap for your snack drawer, our iHTF Baked Ragi Chips are made from finger millet and baked, not fried — a small change rooted in exactly the kind of traditional wisdom this research is now confirming.

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Frequently Asked Questions

1. What is glycemic index and why does it matter for brain health?

Glycemic index measures how quickly a food raises blood sugar after eating it. High-glycemic-index foods, like white bread and sugary snacks, cause sharp blood sugar spikes, while low-glycemic-index foods, like whole grains and legumes, raise it slowly. Research links repeated blood sugar spikes to insulin resistance, which may increase dementia and Alzheimer's disease risk over time.

2. Which foods have a low glycemic index?

Low-glycemic-index foods include most legumes such as lentils, chickpeas, and beans, whole grains like oats and millets such as ragi, most fruits, and non-starchy vegetables. These foods digest slowly because of their fiber content, which prevents the rapid blood sugar spikes associated with refined carbohydrates like white rice, maida, and sugary packaged snacks.

3. Can changing my diet really lower dementia risk this late in life?

Diet is one of several modifiable factors researchers link to dementia risk, alongside exercise, sleep, and managing blood pressure. A 2025 study of over 200,000 adults found low-glycemic-index diets were linked to a 16 percent lower Alzheimer's risk, suggesting dietary changes at almost any age may offer meaningful, long-term protective benefits for the brain.

4. Are traditional Indian grains like ragi and jowar good for brain health?

Millets like ragi and jowar have a naturally low glycemic index compared to polished rice or refined wheat flour, meaning they release sugar into the bloodstream more slowly. Since low-glycemic diets are linked to reduced dementia risk, regularly including these traditional grains in meals may be a simple, practical way to support long-term brain health.