- Consuming less sugar before birth and during the first 1 to 2 years of life was tied to a lower risk of dementia decades later, U.K. Biobank data showed.
- The study used the abrupt end of World War II rationing as a natural experiment to test whether early-life sugar exposure was associated with late-life dementia.
- Previous research has linked early-life sugar rationing to less risk of diabetes and hypertension in adults and better cardiovascular outcomes.
People who consumed less sugar in utero and before age 2 had a lower risk of developing dementia later in life, data from 65,000 U.K. Biobank participants suggested.
The study used the abrupt end of World War II sugar rationing in the U.K. as a natural experiment to test whether sugar exposure during different windows in the first 1,000 days from conception was tied to later all-cause dementia, Alzheimer’s disease, or vascular dementia.
Compared with people not exposed to sugar rationing, risks of all-cause dementia (HR 0.79, 95% CI 0.66-0.94) and Alzheimer’s disease (HR 0.77, 95% CI 0.59-1.00) were lower for people who had sugar rationing in utero and their first year of life, reported Jiazhen Zheng, PhD, of the Hong Kong University of Science and Technology in Guangzhou, China, and colleagues. Associations with vascular dementia were not significant.
Similar relationships emerged for in utero exposure to sugar rationing plus the first 1 to 2 years of life (all-cause dementia HR 0.77; Alzheimer’s disease HR 0.72), Zheng and co-authors wrote in Neurology.
Rationing in utero that extended to ages 1 to 2 years was tied to dementia being delayed by 2.55 years. Incident type 2 diabetes and hypertension jointly mediated 25.5% of the association.
In an imaging substudy, early-life sugar rationing was associated with higher total gray matter volume, lower white matter hyperintensity volume, and better performance in processing speed and reasoning, the researchers added.
Several pathways may explain these findings, Zheng suggested. “Excessive sugar exposure during pregnancy may contribute to maternal hyperglycemia, insulin resistance, and inflammation, potentially affecting placental function and fetal brain development,” he told MedPage Today.
“Early-life nutrition may also shape synaptic maturation, myelination, and long-term cognitive reserve, although these potential mechanisms were not directly examined in our study,” Zheng added. “In our analysis, diabetes and hypertension jointly explained about one-quarter of the association, suggesting that metabolic and vascular health may also play an important role.”
Previous research has linked early-life sugar rationing to less risk of diabetes and hypertension in adults and better cardiovascular outcomes.
“Most of the work so far has gone into establishing that these long-term effects exist. What actually carries them is much less studied,” said Tadeja Gracner, PhD, of the University of Southern California in Los Angeles, who has researched this cohort but wasn’t involved with the current study.
“In our work, we’ve tried to pin down a few. One is that the diet itself persists: Sweet preferences form early, and we find that people rationed as infants or toddlers were still eating less added sugar and more fiber 50 years later,” Gracner told MedPage Today.
“We also find that rationing shifted schooling, occupation, and wealth and those could shape later health, including cognition,” she continued.
“Interestingly, the effects do not seem evenly spread,” Gracner pointed out. “They concentrate among people genetically predisposed to obesity: In our current work in progress, we showed that early sugar restriction narrowed the genetic gap in adult obesity by about 40%. None of these rule each other out, and how much each contributes is still very much open.”
Zheng and colleagues studied 64,737 U.K. Biobank participants who were born before and after World War II sugar rationing. Sugar became widely available again in 1953.
Other foods were rationed but sugar was the only one with a rapid rise in consumption when rationing ended, the researchers noted. “According to National Food Survey data, sugar intake rose by over 50% post-rationing, while fat consumption showed a modest increase, and most other commodities changed minimally,” they wrote.
The cohort included 56.4% women. Overall, 40,963 participants were exposed to sugar rationing during fetal or early childhood life, and 23,774 participants were unexposed.
Participants were 55 years old on average when they entered the study. ICD-10 codes from medical records were used to determine incident dementia diagnoses up to 15 years later. Brain MRI and cognitive function were assessed in a subcohort with a mean age of 62.
Sugar intake during rationing aligned with current U.S. dietary guidelines and American Heart Association recommendations, the researchers noted.
The study findings do not support restricting overall calories or essential nutrients during pregnancy or infancy, Zheng emphasized.
“Rather, they suggest that guideline-consistent reductions in added and free sugars during the first 1,000 days may have long-term brain-health benefits,” he said. “As this was an observational natural experiment study, further research is needed before drawing causal conclusions.”
