In a recent study published in the Nutrition Journal, researchers examined a prospective population-based United Kingdom (U.K.) Biobank cohort to examine associations between free and intrinsic sugar sources and the risk of dementia.

Study: Association of sugar intake from different sources with incident dementia in the prospective cohort of UK Biobank participants. Image Credit: Valerii__Dex / Shutterstock

Background

Dementia is characterized as a decline in cognitive function beyond the level associated with normal aging. There are approximately 55 million cases of dementia across the world, and the incidence increases by 10 million cases each year. Furthermore, while age is an established risk factor for dementia, obesity and overweight during mid-life are believed to increase the risk of dementia. However, despite the extensive research conducted on dementia and its risk factors, there are no effective treatments to date, and lifestyle and dietary interventions remain the primary approaches to slow the progression of the disease.

Dietary interventions to slow the progression of dementia often also address problems of obesity and overweight. A low-carbohydrate diet is believed to improve glucose control and reduce low-grade inflammation while providing promising results in delaying dementia. However, the absence of diverse food choices is often a limitation to achieving a low-carbohydrate diet, as adherence to the diet might require excluding foods such as whole grains, legumes, and some fruits and vegetables that are thought to improve cognition. Therefore, recent studies have focused on limiting specific carbohydrates such as sugars.

About the study

In the present study, the researchers examined the association between an increased risk of dementia and the consumption of free and intrinsic sugar sources. Free sugars are those that are added to foods during manufacturing, cooking, or consumption, while intrinsic sugars naturally occur in foods, such as those in vegetables, fruits, honey, and dairy products.

The World Health Organization recommends that the consumption of free sugars be below 10% of the total energy intake and less than 5% per day. To understand whether consumption of free sugars from various sources, such as solid foods, beverages, and subtypes of solid foods and beverages, was associated with an increased risk of dementia, the researchers conducted a prospective cohort study using a population of U.K. Biobank participants.

The researchers hypothesized that the correlation between free sugar consumption and incident dementia would be dependent on the source of free sugars, with free sugars from beverages and beverage subtypes showing a positive association with incident dementia but a similar association being absent between free sugars from solid foods. They also examined whether consumption of intrinsic sugars was associated with an increased dementia risk.

The study included U.K. Biobank participants who had filled out at least one online dietary questionnaire assessing the 24-hour dietary intake. Those participants for whom information on lifestyle risk factors, socioeconomic factors such as household income, Townsend deprivation index, ethnic background, and educational qualifications, and health parameters such as systolic blood pressure and body mass index were missing, as well as those who had been diagnosed with dementia before the administration of the questionnaire, or had a history of diabetes, were excluded from the study.

Sugar intake was assessed based on the specific food types reported in the web-based questionnaire, such as fruit juices, milk-based drinks, coffee, tea, treats, sauces, toppings, and breakfast cereals. The examined primary outcome was the incidence of all-cause dementia.

Results

The results reported a linear association between the consumption of free sugars in beverages such as fruit drinks, sodas, and milk-based drinks and the risk of dementia. Free and intrinsic sugar intake showed significant associations with the risk of dementia, with a J-shaped association and the lowest hazard ratios being observed at 8% and 9% of intrinsic and free-sugar consumption, respectively.

While the consumption of free sugars in beverages showed a significant and linear association with the risk of incident dementia, no significant association was observed between dementia risk and the consumption of free sugars through solid foods.

Furthermore, within the various subtypes of beverages that were examined, fruit drinks, sodas, and milk-based drinks showed a positive and significant association with the risk of dementia, while juices showed similar associations, but to a lesser extent. Tea and coffee did not show any significant association with dementia risk.

Conclusions

Overall, the findings reported that consuming free sugars, primarily through beverages such as fruit, milk-based drinks, and sodas, increased the risk of incident dementia. Fruit juices showed a similar association, but to a lesser extent, while consuming free sugars through coffee and tea was not associated with an increased risk of dementia. Free sugars consumed through solid foods were not linked to an increased risk of dementia.

Written by

Dr. Chinta Sidharthan

Chinta Sidharthan is a writer based in Bangalore, India. Her academic background is in evolutionary biology and genetics, and she has extensive experience in scientific research, teaching, science writing, and herpetology. Chinta holds a Ph.D. in evolutionary biology from the Indian Institute of Science and is passionate about science education, writing, animals, wildlife, and conservation. For her doctoral research, she explored the origins and diversification of blindsnakes in India, as a part of which she did extensive fieldwork in the jungles of southern India. She has received the Canadian Governor General’s bronze medal and Bangalore University gold medal for academic excellence and published her research in high-impact journals.