Do Zero-Sugar Drinks Age Your Brain? New Study on Sweeteners & Cognitive Decline

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Sugar Substitutes and the Brain: Do Zero Products Really Accelerate Brain Aging?

Posted on: 09/03/2026

Sugar Substitutes and the Brain: Do Zero Products Really Accelerate Brain Aging?

Zero-sugar sodas, sugar-free yogurts, low-calorie desserts, and protein bars have become a common part of many people’s diets. Many choose these products as an alternative to regular sugar — especially when trying to reduce calorie intake or limit added sugar consumption.

But a new study has raised questions about the possible effects of sugar substitutes on the brain. Does this mean Coca-Cola Zero and other sugar-free products are actually harmful? Let’s take a closer look at what researchers found and how concerning these results really are.

What Did the Study on Sugar Substitutes Show?

The study was published in the medical journal Neurology. Researchers used data from the large Brazilian ELSA-Brasil cohort and followed 12,772 adults for an average of about eight years. The average age of participants was approximately 52 years.

Participants provided information about their diets, and researchers estimated how much low- and no-calorie sweeteners they consumed from foods and beverages.

Throughout the follow-up period, participants also completed cognitive tests several times. Researchers evaluated different aspects of brain function, including:

* memory;

* information processing speed;

* verbal fluency;

* overall cognitive performance.

The researchers then compared how quickly cognitive test results changed among people with different levels of sugar substitute consumption.

How Much Faster Did Cognitive Function Decline?

Participants were divided into groups based on their intake of sweeteners.

People with the lowest intake consumed about 20 mg of sugar substitutes per day on average, while those in the highest-consumption group consumed around 191 mg per day.

After adjusting for factors such as age, sex, high blood pressure, cardiovascular disease, and other variables, researchers found that people in the highest-consumption group experienced an overall decline in cognitive function approximately 63% faster than those with the lowest intake.

Researchers estimated that this difference was roughly equivalent to 1.6 additional years of age-related cognitive decline.

However, it is important to understand what this number actually means.

This does not mean that someone’s memory became 63% worse. It refers to a statistical difference in the rate of change in cognitive test scores over approximately eight years of follow-up.

The “1.6 years of aging” comparison is simply a way researchers used to make the size of the difference easier to understand.

Which Sugar Substitutes Were Studied?

Researchers looked at seven low- and no-calorie sweeteners:

* aspartame;

* saccharin;

* acesulfame potassium;

* erythritol;

* sorbitol;

* xylitol;

* tagatose.

A link with faster cognitive decline was found for almost all of them — including aspartame, saccharin, acesulfame potassium, erythritol, sorbitol, and xylitol.

The strongest differences were seen in measures related to memory and verbal fluency.

However, these substances belong to different categories. For example, aspartame and saccharin are high-intensity sweeteners, while erythritol, sorbitol, and xylitol are sugar alcohols.

Therefore, the results cannot simply be interpreted as meaning that one specific type of sweetener is responsible.

Is One Can of Zero Soda Already Dangerous for the Brain?

No. The study does not allow us to make that conclusion.

The highest average intake of all studied sweeteners was around 191 mg per day. Researchers noted that if this amount came only from aspartame, it could be roughly comparable to the amount found in one can of diet soda.

But this does not mean that drinking one can of Zero every day has been proven to accelerate brain aging.

There are two important reasons:

First, participants consumed sweeteners from multiple sources, not just soda.

Second, this was an observational study. It can show a statistical association between two factors, but it cannot prove that sugar substitutes themselves caused faster cognitive decline.

Why Doesn’t This Study Prove That Sugar Substitutes “Kill the Brain”?

This is the key point that often gets lost in dramatic headlines.

The study was observational, not a controlled experiment where people were randomly assigned to consume certain amounts of sweeteners for years.

Researchers adjusted for many factors that can influence brain health. However, it is impossible to completely eliminate the impact of lifestyle, overall diet, and health conditions.

In addition, sugar substitute intake was estimated based on dietary information reported by participants themselves. This approach is commonly used in nutrition research, but it cannot perfectly measure someone’s actual consumption.

The authors highlighted several limitations, including self-reported dietary data, possible participant dropout effects, and remaining lifestyle-related factors that could influence the results.

Therefore, the most accurate conclusion is:

Higher consumption of certain sugar substitutes was associated with faster cognitive decline.

But claiming that sugar substitutes directly cause brain aging would go beyond what this study can prove.

Why Was the Association Stronger in People Under 60?

One of the most interesting findings was the difference between age groups.

The association between higher sugar substitute intake and faster cognitive decline was mainly observed among participants younger than 60 years old.

Among people over 60, researchers did not find a statistically significant association between sweetener intake and cognitive decline.

However, this does not mean that sugar substitutes become “safe for the brain” after 60. More research is needed to understand why the results differed between age groups.

What About People With Diabetes?

Researchers also looked at differences depending on whether participants had diabetes.

Among people with diabetes, higher sugar substitute consumption was associated with faster declines in memory and overall cognitive performance. In some analyses, the association appeared stronger compared with people without diabetes.

This is particularly interesting because people with diabetes often choose sugar-free products as an alternative to sugary drinks and desserts.

However, even here, the results do not prove a direct cause-and-effect relationship.

Does This Mean You Should Avoid Aspartame and Other Sweeteners?

Not based on this one observational study alone.

For example, established safety limits for aspartame consumption have not changed because of these findings. This research looked at the long-term association between sweetener intake and cognitive function, not whether a specific dose of sweetener is toxic.

At the same time, the results highlight why products labeled “sugar-free” should not automatically be considered healthy.

Sugar substitutes can be a useful tool if they help reduce added sugar intake. But “sugar-free” is simply a product characteristic — it is not a guarantee of nutritional value.

Should You Replace Regular Coca-Cola With Coca-Cola Zero?

There is no universal answer.

If someone regularly drinks large amounts of sugary soda, switching to a sugar-free version can reduce sugar and calorie intake/However, the goal should not necessarily be to drink the same amount of Zero soda forever.

If possible, some sweet drinks can gradually be replaced with water, sparkling water, unsweetened tea, or other beverages that do not maintain a constant preference for an intensely sweet taste.

The better question is not simply “sugar or aspartame?” but rather: what role do sweet drinks play in your overall diet?

What Should You Do After This Study?

There is no need to throw away every product containing sugar substitutes.

But it is also not a good idea to view sugar-free products as something you can consume without limits.

A balanced approach:

* do not make products with sugar substitutes the foundation of your diet;

* consider all sources of sweeteners, not just soda;

* choose water and unsweetened beverages more often;

* do not treat “zero sugar” as a synonym for “healthy”;

* evaluate your overall eating pattern.

It is also important not to go to the opposite extreme and return to consuming large amounts of sugar simply because a new study raised questions about sugar substitutes.

The label “sugar-free” only means that a product does not contain added sugar or contains it within the limits required for that label. It does not tell you how the product fits into your overall diet.

The most reasonable approach to sugar substitutes today is to use them as a tool to reduce sugar intake — not as a reason to maintain a habit of constantly consuming very sweet foods and drinks.

Sources:

Gomes Gonçalves N. et al. Association Between Consumption of Low- and No-Calorie Artificial Sweeteners and Cognitive Decline: An 8-Year Prospective Study.Neurology, 2025; corrected version — 2026.

American Academy of Neurology. Not so sweet: Some sugar substitutes linked to faster cognitive decline. Updated press release including the corrected study data.

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