Excess Sugar Intake Can Increase Dementia Risk By 43%, New Study Shows
Research has long shown a link between diet and dementia risk. Eating patterns such as the Mediterranean diet and MIND diet, which prioritize whole foods (vegetables, fruits, whole grains, lean proteins, and legumes), are consistently linked to improved cognitive function. On the other hand, certain foods and ingredients can increase your risk of cognitive decline.
Not surprisingly, sugar has been under a lot of scrutiny. While we know that excess intake can harm both brain and overall health, researchers of a new study actually explored how sugar interacts with your genetics to impact long-term brain health1.
Here’s what you need to know.
About the study
For this study, researchers asked the questions:
- Does sugar intake (added and total sugar) increase the risk of dementia?
- Does a person’s genetic makeup change this relationship?
To find out, they evaluated dietary data from more than 158,000 people in the UK Biobank, a massive study tracking how genetics, lifestyle, and environment influence disease. They also calculated genetic risk scores for sugar metabolism, gut bacteria (due to the role of the gut-brain axis), and dementia risk.
Over nearly 10 years, they monitored the number of participants diagnosed with dementia.
Added sugar raises dementia risk
Results confirmed those of past studies. Sugar intake increased the risk of dementia.
More specifically, higher intakes of free sugars (those added to foods or found in foods like syrups and fruit juices) were linked to a 43% higher risk of dementia.
Even sugars naturally found in foods like fruits and dairy were linked to some increased risk, though the effect was smaller (although the presence of protective fiber and antioxidants in these foods outweighs any potential downside).
The study also showed that genetics does influence risk. Participants with genes tied to poor sugar metabolism, certain gut microbes, or higher dementia risk were more vulnerable to sugar’s effects.
Two gut bacteria, Oscillospira and Ruminococcaceae UCG-014, stood out as particularly influential.
Why are added sugars especially harmful?
Added sugars and free sugars (those found in pure sugar sources like syrup, honey, and fruit juice), are quickly absorbed into the bloodstream, spiking your blood sugar and insulin. And, these foods lack the fiber and nutrients that protect your brain, which may make them especially harmful over time.
How to actually lower your dementia risk
Reducing intake of free and added sugars is a great way to protect your cognition. That can look like opting for plain Greek yogurt over sweetened ones, replacing carby processed snacks with whole food snacks (like one of these), swap sugar drinks with unsweetened ones (here’s what you can add to your coffee instead), and cook most meals at home.
Other science-backed ways to reduce dementia risk include:
- Limit alcohol intake: Studies show that excessive alcohol intake increases the likelihood of dementia and Alzheimer’s disease. If you currently consume alcohol, it’s a smart idea to reduce the volume and frequency at which you do so.
- Take a vitamin D supplement: Vitamin D has a lot of important roles in the body, including protecting your cognition. One study of over 1,600 older adults found that even those with a moderate vitamin D deficiency had a 50-70% higher risk of dementia. Supplementation is the most effective way at preventing (or correcting) a deficiency. These are the expert-approved vitamin D supplements we recommend.
- Stay physically active: Exercise isn’t just good for your heart. It also helps your brain. A 2024 study shows that everyday physical activity, from walking the dog to household chores, can improve cognitive processing speed—keeping your brain sharp.
- Prioritize sleep: Getting enough quality sleep is one of the most powerful factors in maintaining cognitive health. Sleep supports memory retention and recall and reduces brain inflammation.
The takeaway
Diet and lifestyle aren’t the only factors that influence dementia risk, but they certainly play an important role. Reducing added sugar intake is a simple yet powder tool in protecting your long-term cognition.
