A new study suggests that limiting sugar intake during pregnancy and the first two years of life may have lasting benefits for brain health, reducing the risk of dementia decades later. The research, published in the journal Science Translational Medicine, draws on a natural experiment created by Britain's wartime sugar rationing.
During and after World War II, the UK government imposed strict limits on sugar consumption. Rationing ended in 1953, and average daily sugar intake nearly doubled, from about 41 grams to 80 grams. This sharp change allowed researchers to compare people whose early development occurred under sugar scarcity with those born after restrictions were lifted.
The team, led by Jiazhen Zheng of the Hong Kong University of Science and Technology in Guangzhou, analysed data from nearly 65,000 British adults. Participants were grouped by their exposure to rationing: before birth and during the first year of life, before birth and up to age two, or born after rationing ended. Using medical records from around age 55, the researchers tracked dementia diagnoses over the following 15 years.
Results showed that people exposed to sugar rationing before birth and during their first year had a 21% lower risk of dementia than those born after rationing ended. For those exposed up to age two, the risk reduction was 23%. Among those who did develop dementia, the diagnosis came on average 2.6 years later in the rationed group.
Why early nutrition matters
The findings add to a growing body of evidence that the first 1,000 days of life—from conception to age two—are critical for long-term health. "Limiting sugar during the earliest stages of life may have lasting benefits for brain health," Zheng said. "These results highlight the potential importance of early-life nutrition in reducing the risk of dementia decades later."
The study also examined brain health markers, such as brain volume and cognitive function, in a subset of participants. Those exposed to lower sugar levels early in life showed more favourable profiles, suggesting that the protective effect may be linked to structural differences in the brain.
"Sugar restriction in the first 1,000 days was associated with lower dementia hazards, delayed onset, and more favorable brain-health profiles," the researchers wrote. They added that the findings support reducing sugar intake early in life as a potential strategy to lower dementia risk.
While the study is observational and cannot prove causation, it offers a rare glimpse into the long-term effects of dietary policy. The UK's rationing programme was not designed as an experiment, but it created a clear before-and-after comparison that is difficult to replicate ethically today.
Zheng stressed that further research is needed to understand the mechanisms linking early sugar exposure to dementia risk. "Limiting added sugars during pregnancy and infancy may be one beneficial step that families and communities can take," she said, but cautioned that the findings should not be overinterpreted.
The study comes as European health authorities grapple with rising rates of obesity and type 2 diabetes, conditions that are themselves risk factors for dementia. In countries like Germany, France, and the Nordic states, public health campaigns have already pushed for reduced sugar consumption, but this research suggests the benefits may begin even earlier than previously thought.
For policymakers, the findings reinforce the importance of early-life nutrition. As chronic stress has been linked to faster brain ageing, dietary factors may play a similarly influential role. The study also echoes broader concerns about the health impacts of industrial food systems, which often rely on high-sugar processed products.
While the study focused on the UK, its implications extend across Europe, where dietary habits vary widely. In southern Europe, traditional Mediterranean diets are naturally lower in added sugar, but even there, consumption of sugary drinks and snacks has risen in recent decades. The findings suggest that public health interventions targeting sugar intake in pregnant women and young children could yield significant long-term dividends.
As dementia rates continue to climb across the continent, with an estimated 10 million people living with the condition in Europe, identifying modifiable risk factors is crucial. This study points to a simple, early-life intervention that could have a profound impact on brain health in later life.
