Reach for a "sugar-free" sweet or a diet cola, and it feels like the safe choice — zero sugar, zero guilt. But a new study is asking whether that trade-off might be quietly costing us something else entirely: our brain's pace of aging.

• A new 8-year study of 12,772 adults linked higher intake of common sugar substitutes to faster cognitive decline
• Adults with the highest sweetener intake showed cognitive aging roughly 1.6 years faster than low consumers
• Six of the seven sweeteners studied, including aspartame, saccharin, and sorbitol, were tied to memory decline
• Tagatose, a lesser-known sweetener, was the one exception with no link to cognitive decline
• The effects were strongest in adults under 60 and in people living with diabetes

Yes, a large new study suggests that regularly consuming certain low- and no-calorie sweeteners may be linked to faster brain aging. Published in Neurology, the journal of the American Academy of Neurology, on July 18, 2026, the research tracked 12,772 adults in Brazil for close to eight years, comparing sweetener intake with performance on cognitive tests. Adults who consumed the most sweeteners, roughly the amount of aspartame in one diet soda a day, showed cognitive decline about 62 percent faster than those who consumed the least, a gap researchers estimated at around 1.6 years of extra brain aging. It is an observational study, so it cannot prove cause and effect on its own, but the pattern was consistent enough that the researchers are urging caution.

What the researchers actually measured

The study followed participants from Brazil's long-running adult health cohort, collecting detailed dietary questionnaires at the start and cognitive assessments at the beginning, middle, and end of the roughly eight-year period. Participants were split into three groups based on total sweetener intake: the lowest group averaged about 20 mg a day, while the highest averaged around 191 mg a day. Cognitive testing covered verbal fluency, working memory, word recall, and processing speed. Even the middle-intake group showed 35 percent faster decline than the lowest group, equal to about 1.3 years of additional cognitive aging, suggesting the effect was not limited to only the heaviest consumers.

Which sweeteners were involved, and which one was not

Seven sweeteners were examined in total: aspartame, saccharin, acesulfame K, erythritol, xylitol, sorbitol, and tagatose. Sorbitol had the highest average individual intake at 64 mg a day, often from sugar-free gums and diet foods. Six of the seven were associated with faster memory decline. Tagatose stood apart, showing no measurable association with cognitive decline, though researchers note it is used far less widely than the others, so more data is needed before drawing firm conclusions about it.

Why sweeteners might affect brain aging

Scientists do not yet fully understand the mechanism, but a few theories are gaining attention. Some researchers point to how non-nutritive sweeteners can alter the gut microbiota, the community of bacteria that communicates with the brain through the gut-brain axis. Others suggest certain sweeteners may influence blood vessel function or metabolic signalling in ways that natural sugars and whole foods do not. As one of the study's authors put it, "Low- and no-calorie sweeteners are often seen as a healthy alternative to sugar, however our findings suggest certain sweeteners may have negative effects on brain health over time." The researchers were careful to note that self-reported diet data has its limits, and that this study shows association, not proof of cause.

Who should pay closer attention

The link to faster cognitive decline was strongest in adults under 60 and in people with diabetes. That is a meaningful detail, since many people with diabetes turn to aspartame and similar sweeteners specifically to manage blood sugar. It does not mean these choices are wrong for everyone, but it is a reason to talk to a doctor about which sweeteners, if any, make sense for your situation, rather than assuming all "sugar-free" options are automatically the safer pick.

What this means for your everyday choices

None of this means you need to panic over the occasional diet drink. But it is a good nudge to look at how often sweeteners show up in your day, and to lean more on foods that are naturally sweet instead of chemically sweetened. Traditional Indian sweeteners like dates and jaggery bring natural sugars alongside fibre, potassium, and other nutrients, which is part of why we build treats like our Dry Fruit Ladoo around whole dates and nuts rather than refined sugar or artificial sweeteners. Small, consistent swaps like this add up over years, which is exactly the timescale this study was measuring.

If you are looking to cut back on artificial sweeteners without giving up something sweet at the end of the day, our Nutri Choco Ladoo is a simple place to start, made with cocoa, dates, nuts, and seeds, and no refined sugar.

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Frequently Asked Questions

1. Do artificial sweeteners cause dementia?

Not proven. This 2026 Neurology study found an association between higher intake of certain sweeteners and faster cognitive decline over eight years, but it is observational, meaning it cannot confirm that sweeteners directly cause dementia. Researchers called for further studies to establish whether the link is truly cause and effect.

2. Which sweeteners were linked to faster brain aging in the study?

Six of the seven sweeteners studied were linked to memory decline: aspartame, saccharin, acesulfame K, erythritol, xylitol, and sorbitol. Tagatose was the only one with no measurable association. Sorbitol had the highest average daily intake among participants, largely from sugar-free gums and packaged diet foods.

3. Is aspartame safe to consume?

Health authorities including the WHO and food safety agencies still classify aspartame as safe within set daily limits. This new study adds a note of caution around long-term brain health at higher intakes, but it does not overturn existing safety guidance. It is a reason for moderation, not alarm.

4. Should people with diabetes avoid artificial sweeteners because of this study?

Not necessarily. The study found stronger effects in people with diabetes, which is worth discussing with a doctor, but sweeteners still help many people manage blood sugar. The better takeaway is to vary sweetener sources, favour whole foods where possible, and get personalised advice rather than stopping cold turkey.

5. What is tagatose and why is it different?

Tagatose is a naturally occurring, low-calorie sugar found in small amounts in dairy and some fruits. In this study, it was the only sweetener among seven tested that showed no link to faster cognitive decline, though researchers note it is used far less often, so more research is needed to confirm this pattern.