Early-Life Sugar Restriction and Long-Term Risk of Cancer: A Natural Experiment Study in the UK

Objective: To examine whether early-life exposure to sugar rationing is associated with reduced risk of cancer and cardiometabolic disease in adulthood, leveraging a natural experiment created by the abrupt end of post-war sugar rationing in the United Kingdom on 26 September 1953. Design: Natural experiment study using an event-study design based on variation in the duration of exposure to sugar rationing during the first 1000 days of life (from conception to age 2 years). Setting: UK Biobank, a large prospective cohort recruited from across the UK. Participants: 64,761 UK Biobank participants born between 1951 and 1956, a window spanning the 1953 de-rationing event. Exposure to sugar restriction was determined by birth date relative to the policy change. Individuals with multiple births, adoption, birth outside the UK, or pre-existing disease were excluded. Main outcome measures: Adult incidence of major cancers, digestive (liver, rectum), respiratory (lung), and hormonesensitive (prostate, breast), estimated using Cox proportional hazards models. We also assessed long-term behavioural outcomes (dietary patterns) and biological markers (leukocyte telomere length; circulating Granzyme B). Results: Longer exposure to sugar rationing during early life was associated with lower risk of multiple diseases in adulthood. Participants exposed in utero plus one to two years had lower incidence of digestive cancers (liver: hazard ratio 0.31, 95% confidence interval 0.18 to 0.49; rectum: 0.60, 0.51 to 0.69), respiratory cancer (lung: 0.59, 0.50 to 0.68), and hormonesensitive cancers (prostate: 0.48, 0.43 to 0.55; breast: 0.64, 0.58 to 0.70). Mechanisms: Two complementary mechanisms were identified: (1) a behavioural programming pathway, wherein early-life restriction led to a persistent hedonic shift resulting in lower sugar intake and healthier dietary habits five decades later; and (2) a biological imprinting pathway, evidenced by 0.05 SD longer leukocyte telomere length (≈ 2.2 years less biological ageing) and lower circulating Granzyme B levels. Conclusion: Exposure to sugar restriction during the first 1,000 days was associated with lower cancer and slower biological ageing, offering rare causal evidence that early-life nutrition can permanently shape disease susceptibility. During rationing, adults consumed about 40 g/day of sugar, well within WHO-recommended levels, whereas intake doubled to roughly 80g/day once controls ended. This natural contrast shows that maintaining WHO-level sugar intake in early life can yield lasting health benefits. With current consumption far above recommended thresholds, the case for early-life sugar reduction is both urgent and highly consequential.