For 13 years, from 1940 to 1953, sugar was rationed in the United Kingdom as a result of World War II and its aftermath. Adults were allowed about 40 grams a day, while children received less. Babies and very young children were not expected to consume added sugar.
Decades later, the restrictions have become an unusual source of scientific evidence about how sugar consumption in early life may affect health well into adulthood.
Researchers have used the experience of people born before and after rationing ended to investigate the long-term consequences of early exposure to sugar. Their findings link lower sugar consumption during pregnancy and the first two years of life to reduced risks of several chronic conditions, including Type 2 diabetes, high blood pressure and anxiety disorders.
The studies also suggest a possible association with slower biological aging and lower rates of age-related diseases. Researchers caution, however, that the evidence comes from a natural experiment rather than a clinical trial, meaning individual mothers’ and children’s sugar consumption was not measured precisely.
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A natural experiment created by wartime rationing
Under Britain’s rationing system, adults could consume approximately three tablespoons of sugar, or 40 grams, a day. The allowance had to cover all uses, from sweetening tea to baking and confectionery. Children were limited to less than one tablespoon daily, while infants and very young children were not expected to receive additional sugar.
Restrictions began to ease in 1953. Rationing of sweets and chocolate ended in February, and sugar rationing was fully abolished in September. By the second half of 1954, average sugar consumption in Britain had almost doubled.
This abrupt change created two groups of people whose early-life environments differed substantially in their exposure to sugar. Some had experienced the restrictions only in the womb, others throughout infancy and childhood, and those born after rationing ended were not exposed to the restrictions even before birth.
The circumstances provided researchers with a rare opportunity to compare long-term health outcomes among people born relatively close together but exposed to different levels of sugar availability during the first 1,000 days from conception to approximately age 2.
Dr. Tadeja Gračner of the Center for Social and Economic Research at the University of Southern Californiaand her colleagues began investigating the issue using data from the UK Biobank, a large British health database. Their initial findings were published in the journal Science in 2024.
Gračner told To BHMA-Science that the end of rationing produced a rapid increase in sugar consumption, while consumption of most other foods changed relatively little.
Comparing medical records from the two groups decades later allowed researchers to examine the long-term health effects associated with early exposure to sugar more reliably than conventional observational studies, she said.
But she emphasized an important limitation: “This was a natural experiment, not a clinical trial. We know the dietary environment the population was exposed to, but not exactly how much sugar each mother and child consumed.”
Lower risks of diabetes and high blood pressure
The initial findings linked restricted sugar consumption during the first 1,000 days of life with significant health benefits in middle age and beyond.
People who experienced sugar rationing during their first two years had a 35% lower risk of developing Type 2 diabetes and a 20% lower risk of hypertension than those who were never exposed to the restrictions.
The findings also suggested that early-life sugar restriction delayed the diagnosis of Type 2 diabetes by approximately four years and hypertension by about two years.
The benefits appeared to increase the longer low sugar consumption continued after birth.
Further analyses of UK Biobank data have since linked lower sugar exposure early in life to reduced risks of problems affecting several bodily systems, including the cardiovascular and respiratory systems, the liver and the brain. Researchers also found an association with a lower likelihood of developing dementia.
A study published in Nature Communications in July by researchers at the Hong Kong University of Science and Technology found that people exposed to Britain’s sugar restrictions during their early years had a lower incidence of age-related diseases and a biological age at least one year younger than that of people who were not exposed to rationing.
Early sugar exposure and mental health
The potential effects may also extend to mental health.
In August, researchers from the University of Surrey, led by Professor Nophar Geifman, reported in the journal Translational Psychiatry that people who experienced sugar rationing during their first 1,000 days of life had a 33% lower risk of being diagnosed with an anxiety disorder than those born after restrictions had ended.
Geifman told To BHMA-Science that the association appeared to persist even though sugar consumption among those who had experienced rationing increased after the restrictions were lifted.
“Our findings suggest that diet early in life has a long-term association with mental health,” she said.
The researchers also observed that some people exposed to sugar restrictions during their early years appeared to have less of a preference for sweets in adulthood.
What the findings mean for today’s parents
The research adds to evidence supporting efforts to limit added sugar during pregnancy and early childhood. It does not, however, establish a specific safe upper limit for sugar consumption.
Gračner stressed that a distinction must be made between added or free sugars and sugars naturally present in foods such as fruit, vegetables and milk.
Existing health recommendations provide guidance. The World Health Organization advises keeping free sugars below 10% of total daily energy intake, with a further reduction to below 5% recommended for additional health benefits.
The American Heart Association recommends that children younger than 2 consume no added sugar. For children ages 2 to 18, it recommends a limit of 25 grams a day, equivalent to about six teaspoons.
Gračner also emphasized that Britain’s wartime rationing reduced sugar consumption rather than eliminating it entirely. This distinguishes the experience from wartime famines, including those in the Netherlands, where prolonged shortages of numerous nutrients—not just sugar—were associated with adverse health effects.
The British experience therefore offers a different perspective on the consequences of dietary restriction: it provides an opportunity to examine what may happen when sugar consumption is reduced while most other foods remain available.
Hidden sugar remains a concern
Researchers say the issue today is not occasional consumption of sweets but the routine exposure to added sugar, including sugar hidden in processed foods marketed to infants and young children.
Gračner argued that parents need support from public authorities, schools, advertisers and the food industry, rather than being left to shoulder the responsibility alone.
Geifman similarly warned that growing evidence points to adverse health effects from processed—and particularly ultraprocessed—foods high in sugar, with some effects potentially beginning before birth.
For parents seeking to protect young children’s health during a critical period of development, she said, avoiding processed foods containing hidden sugar could be an important step.
The studies, she added, represent one part of the evidence needed to shape public health policies and recommendations for future generations.
The broader message is that dietary habits in pregnancy and early childhood may have consequences lasting well into adulthood. While the research does not establish that sugar restriction alone accounts for all the observed benefits, it provides further evidence for minimizing added sugar during the earliest stages of life.