Sugar Linked to 43% Higher Dementia Risk

A new study suggests that eating a lot of sugar (particularly added sugar) may raise your risk of developing dementia—and your genes could make that risk even higher. For a new study, researchers tracked more than 158,000 mostly middle-aged adults over nearly a decade and found that higher sugar intakes were linked to a significantly greater chance of developing dementia, with certain genetic traits amplifying that risk.

While dementia is often viewed as a disease of old age, its biological groundwork can be laid decades earlier. In the United States, about 1.7% of adults aged 65 to 74 are living with a diagnosed form of dementia, with rates climbing sharply after age 75. This study followed people in their mid-50s to assess whether sugar intake at that stage of life was linked to a greater risk of developing dementia over the following decade—before symptoms typically appear.

Previous research has linked high added sugar intake to a greater risk of dementia, but few studies have explored how that risk may vary based on a person’s genetic makeup. This new study helps fill that gap, offering a more personalized view of how sugar and genetics may work together to influence long-term brain health.

How Was the Study Conducted?

The study was conducted by a team of medical researchers based in China with expertise in nutrition, epidemiology and chronic disease. They used data from the UK Biobank, a large ongoing health study that includes over 500,000 adults ages 37 to 73 from England, Scotland and Wales. For this analysis, the researchers focused on 158,408 participants—with an average age of 56—who had completed repeated 24-hour dietary recalls and provided genetic samples. 

This allowed the team to estimate each person’s intake of added sugars (like those added to soda, candy and baked goods) and naturally-occurring sugars (naturally found in fruit and dairy) and to calculate genetic risk scores for traits related to sugar metabolism, gut bacteria and dementia susceptibility.

Participants were followed for almost 10 years, and dementia cases were identified through national health records including hospital and death registry data.

What Did the Study Find?

Over the follow-up period, about 0.7% of participants were diagnosed with dementia. That may sound low, but it’s notable considering most people were in their 50s at the start—an age when dementia is still rare.

In addition, the researchers found that people who consumed the most added sugar had a 43% higher risk of developing dementia compared to those who consumed the least. Even sugars naturally found in foods were linked to some increased risk, though the effect was smaller.

Genetics also appeared to make a difference. Participants with certain gut-related genetic traits—specifically a lower score for Ruminococcaceae UCG-014 or a higher score for Oscillospira—were more sensitive to the effects of sugar on dementia risk. These gene-diet interactions suggest consequences depending on their biology.

That said, like all research, this study has limitations. UK Biobank participants are, on average, more health-conscious, less likely to have obesity and more affluent than the general UK population, which means the results may not apply equally to all groups.

It’s also worth noting that about 90% of participants were white. This study didn’t include a racially diverse enough population to explore how sugar, genetics and dementia risk may differ across racial or ethnic groups. Finally, the dietary information was also self-reported, which can introduce some inaccuracy. And while the study found strong links between sugar intake and dementia risk, it doesn’t prove that sugar directly causes the disease. 

How Does This Apply to Real Life?

Dementia affects millions of people and their families. This study suggests that what you eat in your 50s—especially your sugar intake—might influence your brain health years down the road. Sugar intake is a adjustable risk factor, and cutting back on added sugars is smart advice for most people. For those with a genetic predisposition for dementia, doing so might be especially important.

And just because you decide to cut back on added sugar doesn’t mean you can’t satisfy your sweet tooth. Added sugars had a larger impact on dementia than natural sugars, like those found in fruit, so fruit-forward options like Lemon-Raspberry Frozen Yogurt Bites and No-Sugar-Added Mini Apple Pies can be great recipes to work into your routine.

And we have some other simple dessert options—like High-Fiber Black Bean Brownies and Mini New York Cheesecakes—that can add sweetness to your day without giving you a major sugar rush. If you need help resetting your routine to have less added sugar, a meal plan like our weeklong No-Sugar, High-Protein Meal Plan for Beginners could do the trick.

Our Expert Take

What you eat in midlife may have long-term effects on brain health. This study suggests that higher sugar intake—especially in combination with certain genetic traits—may increase the risk of developing dementia. While more research is needed, particularly in more diverse populations, reducing added sugars is a simple, proactive way to support cognitive health as you age.