Reducing sugar intake during the first two years of life may be linked to better brain health and a lower risk of dementia in later years, according to a new study. However, researchers and independent experts caution that the findings show an association rather than proving that sugar directly causes the disease.
The study examined a unique period in the United Kingdom following the end of post-World War II sugar rationing in September 1953. After rationing ended, average daily sugar consumption nearly doubled from about 41 grams to 80 grams, allowing researchers to compare the long-term health outcomes of people exposed to different levels of sugar early in life.
Researchers from the Hong Kong University of Science and Technology analysed health data from nearly 65,000 participants in the UK Biobank.
They found that individuals who spent their first two years of life during the sugar rationing period had a 23% lower risk of developing dementia compared with those born after restrictions ended.
Among participants who later developed dementia, the condition was diagnosed an average of 2.5 years later in those who experienced lower sugar exposure during infancy.
The findings were published in the journal Neurology.
Experts urge caution
Lead researcher Jiaxin Zheng said the results suggest that limiting sugar intake during early childhood could have long-term benefits for brain health. However, Zheng emphasised that further research is needed to determine whether sugar itself is responsible for the observed differences.
Independent experts echoed that caution.
Rachel Richardson, a researcher affiliated with Cochrane, said the study was observational and could not establish a direct cause-and-effect relationship. She also noted that researchers were unable to measure each participant's actual sugar intake.
Professor Ian Maidment of Aston University said the findings should be interpreted carefully because people born in the 1940s and 1950s experienced very different diets, lifestyles and healthcare conditions from those of modern populations.
Dr Sarah Rodriguez of Alzheimer's Research UK described the research as a valuable contribution but said it does not demonstrate that reducing sugar alone can prevent dementia.
She added that maintaining a balanced diet and healthy lifestyle remains one of the best-supported ways to promote long-term brain health.
Importance of early nutrition
Researchers highlighted that the first 1,000 days of life—from pregnancy until around a child's second birthday—are widely recognised as a critical period for brain and physical development.
Previous research has also linked the sharp rise in sugar consumption after the end of UK rationing with higher risks of type 2 diabetes and high blood pressure later in life.
While the study adds to growing evidence that early nutrition may influence long-term health, researchers stressed that its findings should not be directly applied to today's children because of significant differences in diet and living conditions over the past several decades.
