Fact Check
T hey were born into a Britain still recovering from the hardships of war. Though the air-raid sirens had fallen silent, many everyday foods remained rationed, including sugar. Adults were restricted to about 3 tablespoons (40g) a day to stretch between cups of tea, baking and desserts; children were limited to less than a tablespoon.
Babies and very young children were expected to have little or no added sugar. Then, in 1953, the brakes came off. Separate restrictions on sweets and chocolate were lifted in February, followed by sugar in September.
By the second half of 1954, average sugar consumption had almost doubled. A London shopkeeper puts up a sign announcing the new price of sugar, as announced in the budget in September 1939. The price has risen by a penny a pound.
Photograph: Fox Photos/Getty Images The lifting of postwar sugar rationing inadvertently created a natural experiment, whose consequences scientists are only beginning to unpick. A flurry of recent studies suggests that spending the first 1,000 days of life under sugar rationing may have left traces on people’s health more than seven decades later. “What makes the end of sugar rationing particularly interesting is the nature of the exposure,” said Dr Jiazhen Zheng at Hong Kong University of Science and Technology in Guangzhou, China, who worked on several of the recent studies.
“In September 1953, sugar availability changed quite abruptly at the population level, largely because of policy rather than individual choice. In a sense, history created an experiment that we could never deliberately run over a human lifetime.” The first of this recent wave of sugar rationing studies was published in the journal Science two years ago. Dr Tadeja Gračner at the University of Southern California and her colleagues used data from the UK Biobank to compare the health of people born shortly before and after sugar rationing ended in the UK.
Some had been exposed to this low sugar environment only during their time in the womb; others remained exposed for months or years, while those conceived once rationing ended were not exposed at all. Gračner found that the longer people had spent under rationing, the lower their risk of developing type 2 diabetes and high blood pressure in mid- to later life: those exposed throughout their first 1,000 days had a 35% lower risk of type 2 diabetes and a 20% lower risk of high blood pressure than those who had never experienced rationing. The findings prompted Zheng and others to wonder whether these effects might extend to other organ systems.
Over the past few months, further studies drawing on UK Biobank data by his group and others have linked reduced sugar exposure to lower risks of a growing list of health conditions. Schoolboys clamber to enter a sweet shop in 1945. Photograph: Hulton Deutsch/Corbis/Getty Images “I have been more struck by the consistency across different organ systems than by any single effect estimate,” Zheng said.
“In our work, we have seen associations with cardiovascular disease, liver disease, respiratory health, dementia and, more recently, broader measures of ageing. Our ageing study , for example, found a lower overall incidence of diseases linked to the hallmarks of ageing and modestly younger biological and organ ages among people exposed to rationing early in life.” Gračner is not entirely surprised. “Many of these outcomes are connected,” she said.
“Diabetes, hypertension and obesity are major risk factors for cardiovascular disease, cognitive decline and several other conditions, so if early-life sugar restriction affects those upstream risks, associations across a broad set of related outcomes are what one would expect.” Perhaps more surprising is the suggestion that the effects could extend beyond physical health. In August, Prof Nophar Geifman at the University of Surrey and her colleagues reported that people who had spent the full first 1,000 days of life under sugar rationing had a 33% lower risk of being diagnosed with anxiety than those born after rationing ended. They were also less likely to report a preference for sweet foods decades later.
“Despite increased sugar consumption after rationing, early nutritional environments appear to have lasting relevance for mental health,” Geifman said. How such a relatively brief difference in sugar exposure might leave traces detectable many decades later remains uncertain. Gračner said: “ We can show that growing up with less sugar was protective decades later, but not how: whether through sugar itself, through taste preferences formed early, or through a metabolic response set in early life.” A confectionery ad from 1942.
Photograph: John Frost Newspapers/Alamy Her team’s latest research , now under peer review, suggests that growing up under rationing may weaken the influence of genes that predispose people to a higher body weight. “Importantly, while we observe that people exposed to rationing do consume less free sugar in adulthood, we find that dietary difference is similar across genetic-risk groups,” Gračner said. “That points to a response that is not purely behavioural: early nutrition may act on physiological pathways such as metabolic programming, insulin sensitivity, appetite and satiety regulation, or adipose-tissue [fat tissue] development.” Explaining the anxiety finding is slightly trickier.
Geifman says the brain undergoes rapid development in the womb and during the first few years of life, which could make it particularly sensitive to its nutritional environment. High-sugar diets have also been linked to inflammation and an altered gut microbiome – both possible routes through which sugar could affect brain function. A busy shop in April 1953 after rationing ended.
Five months later, sugar availability changed quite abruptly at the population level. Photograph: Grace Robertson/Getty Images Zheng’s ageing study offers another potential clue. It found that people exposed to rationing scored about a year younger on several measures of biological age.
The researchers also detected differences in proteins involved in pathways that help cells respond to nutrients and have been implicated in ageing. “I therefore see biological ageing as a possible shared upstream pathway, rather than necessarily a completely separate phenomenon,” Zheng said. The idea that early-life nutrition can have lasting effects is not new.
Since the 1970s, researchers have used famines as natural experiments to investigate the consequences of severe nutritional deprivation early in life. Much of this research has focused on the Dutch “hunger winter” of 1944-45, when German restrictions on food transport left millions in the western Netherlands facing severe shortages. Because this famine began and ended abruptly in a previously well-nourished population, and because food rations were recorded and detailed birth records survived, researchers have been able to compare those exposed during different stages of pregnancy with those born before the famine or conceived after it ended.
“The most reliable findings are an increased risk of overweight, obesity and type 2 diabetes,” said Prof LH Lumey, an emeritus professor of epidemiology at Columbia Mailman School of Public Health in New York. “People are likely to be more overweight starting from when they are 20 or 30, and they are more likely to have diabetes at age 50 or 60.” A woman shopping in wartime London has coupons removed from her ration book after buying a week’s supply of butter and sugar, circa 1942. Photograph: Chris Ware/Getty Images Although the British rationing studies might appear to point in the opposite direction, the conditions were very different.
“British sugar rationing was not famine, and it did not involve severe overall caloric deprivation. Rather, it selectively constrained sugar intake while the broader diet remained relatively adequate,” Zheng said. The lesson, then, is not simply that less nutrition is better.
“It suggests that the quality and timing of nutrition during early development can have consequences that extend across the life course,” Zheng said. So where does this leave us? Fascinating as the findings are, they don’t prove that differences in early-life sugar consumption caused the later health differences.
“There’s no causality implied,” Geifman said. “It is an association.” A woman registers her family with a grocer for rations of bacon, ham, butter and sugar, circa 1939. Photograph: Fox Photos/Getty Images Many of the recent studies also draw on overlapping groups of UK Biobank participants, meaning they cannot be regarded as independent replications.
“The strongest evidence will ultimately come from triangulation across independent datasets and research designs,” Gračner said. Lumey said the findings represented “a great first step, not the final word. They should be further examined, not to answer the question: is there an association or not?
But is the risk really 30% higher or 50% higher, and does it relate to the first 1,000 days, or only the period in gestation?” Even if the associations eventually prove causal, these current studies cannot tell parents exactly how much sugar is too much. Nor can they pinpoint a single critical window. The evidence so far suggests that exposure during pregnancy matters, but some associations become stronger when rationing continued beyond about six months of age – around the time babies begin eating solid foods.
A Mars bar ad in a magazine in 1943. Photograph: John Frost Newspapers/Alamy “The emerging picture is that the whole first 1,000 days may matter, with pregnancy and the transition to solid foods representing potentially important windows,” Zheng said. “While these findings support existing recommendations to limit unnecessary free or added sugars, they should not be interpreted as evidence that severe dietary restriction is beneficial.” Yet, this postwar experiment may be less divorced from modern life than it first seems.
Sugar consumption under rationing was broadly comparable to levels recommended by current UK guidelines, which state that free sugars – those added to foods and drinks, or naturally present in honey, syrups, smoothies and fruit juices – should not exceed 30g a day for adults and children aged 11 and over, with lower amounts for younger children. “Sugars should not be added to food or drinks given to babies,” NHS guidance says. In practice, average UK consumption is roughly twice the recommended level.
The question raised by these studies is not, therefore, whether today’s infants should experience wartime deprivation, but whether keeping sugar intake closer to already recommended levels may have benefits that extend much further into later life than previously recognised.
Source: The Guardian
