Most research points towards a link between diet and neurological disorders, such as dementia risk. Many dietary experts purport the Mediterranean and MIND diets for longevity and better health in life. Diets that prioritize whole foods such as fruits, vegetables, whole grains, lean proteins and legumes and are linked with better cognitive function.
However, there are certain foods which are detrimental to brain function and may cause cognitive decline. While sugar has never avoided scrutiny, once being accused of causing ADHD in children, recent research explores sugar’s interaction with genetics to impact brain health.
Big picture
A study published in The Journal of Prevention of Alzheimer’s Disease evaluated dietary data from more than 158,000 people in the UK Biobank. They investigated the relationship between sugar intake and increased dementia risk, and whether genetics influences this relationship. Over a decade, they monitored the number of participants who were diagnosed with dementia. The studies connect higher total and free sugar intake with greater dementia incidence over the 10 year period of follow-up.
What the new study asked
The study looked at both free sugars (which are found in foods like syrup and fruit juices) and natural sugars (found in fruits and dairy). The natural sugars were found to have some increased dementia risk, but smaller than that of free sugars. Two key points were highlighted to guide the analysis: Firstly, whether added or total sugars raise dementia risk, and does genetic traits alter that relationship. The studies assessed total sugar, free sugar, and subtypes (sucrose, fructose, lactose) and investigated other influences, including potential sex differences.
Key findings
In summary, the report shows that higher intakes of free sugars were linked to a 43% higher risk of developing dementia. Separate analyses found higher total sugars and specific subtypes, including sucrose, fructose and lactose, were associated with increased risk, particularly among women. The study also demonstrated that genetics influences sugar metabolism and other factors which subsequently influences dementia risk.
Genetics and the gut-brain axis
Genes linked to poor sugar metabolism, higher risk of dementia or poor gut microbes were more vulnerable to sugar’s influence. Oscillospira and Ruminococcaeceae UCG-014 were two gut bacterias that researchers highlighted as influential modifiers in coverage of the study. Papers explicitly evaluating genetic susceptibility report both free and non-free sugars as independent risk factors, with gene scores modifying risk.
Why added sugars are riskier
Free sugars include added sugars and those in syrups, honey, and juices. They are absorbed rapidly in the gut. Free sugars also spike blood glucose and insulin levels quickly. Whereas whole foods contain fiber and protective nutrients, sugars lack these components. Whole foods provide fiber, vitamins, minerals, and antioxidants that help protect health. Research data specifically pinpoint sugars from sugary drinks as contributors to dementia risk.
How this fits prior evidence
Multiple UK Biobank studies link higher sugar intake to higher dementia and Alzheimer’s risk. Researchers report non-linear dose-response curves for absolute and relative sugar intake. Specific sugars, like sucrose and non‑milk extrinsic sugars, show higher risk links. Some analyses find stronger associations in women than in men. Multiple cohorts connect higher sugar intake, including subtypes, with greater dementia risk. Studies also link total sugar and high‑sugar diets to Alzheimer’s disease. Free sugars in drinks show especially clear, roughly linear risk patterns.
Practical risk reduction
Research shows that reducing intake of free and added sugars benefits and protects brain health and cognition. Swap sweetened yogurts for plain unsweetened yogurts, replace sugary snacks with whole foods, and choose unsweetened drinks. Other strategies to use in tandem with reducing sugar intake for better cognition include adequate vitamin D, physical activity, and consuming whole foods. Also research shows limiting alcohol and getting consistent sleep is crucial for memory and inflammation control.
Studies demonstrate a link between excessive alcohol to Alzheimer’s disease and dementia risk. Vitamin D performs various functions in the body which includes protecting and promoting better cognition and brain health. A vitamin D deficiency is linked to higher dementia risk. A study demonstrated that over 1,600 older adults with a moderate Vitamin D deficiency have a 50-70% higher risk of developing dementia. Experts state that supplements are one of the most effective ways to rectify and avoid Vitamin D deficiency.
Limits and what to watch
The research shows links between sugar intake and dementia risk. However, UK Biobank participants are generally healthier than the wider population. They also are less diverse, with most participants identifying as white. This “healthy volunteer” bias can limit how widely we apply the findings.
Dietary recalls can misestimate sugar intake because people misreport what they eat. Studies show links but cannot prove causation. Even so, multiple independent analyses point in the same direction across sugar subtypes and intake levels. Studies also show stronger signals for sugars from sugary beverages, suggesting source or type of food matters for risk. These consistent patterns deserve clinical attention and careful counseling on sugar reduction.
Read More: Researchers Discover Vitamin With Potential to Help Control Blood Sugar Levels