It’s tough news to hear on Halloween: a sugary diet in the first two years of life is linked to a higher risk of diabetes and high blood pressure decades later, according to an analysis of UK sugar rationing in the 1950s.

The amount of sugar a child consumed after turning six months old seemed to have the biggest effect on the risk of developing a chronic disease later in life. But people exposed to more sugar in the womb also had a higher risk of diabetes and high blood pressure compared to those who were conceived when access to sugar was limited.

Economist Tadeja Gračner was pregnant with her first child and on doctor-ordered bed rest when she and her colleagues first arrived at these conclusions, which are published in Science on 31 October¹. “I was like, ‘No, no, no. This is the last thing I need.’,” she says. “I was probably eating a chocolate at the time.”

The results do not mean that pregnant people and parents of young children need to eliminate added sugars from their own diet or their child’s, says Gračner, who works at the University of Southern California in Los Angeles. But there could be room for cutting back: in the United States, pregnant and lactating people typically eat more than three times the recommended amount of added sugar. “It’s all about moderation,” she says.

Childhood diet’s long shadow

The UK study is not the first to link early-life nutrition to disease risk later in life. Previous work has shown that experiencing famine while in the womb can double the risk of diabetes later in life.

But data from tragedies such as famines and war can be difficult to interpret, says Valentina Duque, an economist at American University in Washington DC. “Often, these big, historical shocks affect so many things,” she says. “You don’t know what’s because of nutrition, or stress, or changes in income or household dynamics.”

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Sugar rationing in the United Kingdom offered an opportunity to take a more detailed look at the impact of nutrition on later life. Economic hardship during the Second World War forced the government to institute food rations, and limits on sugar were not lifted until 1953, years after the war ended. By then, most other aspects of nutrition had normalized to meet standard daily recommendations.

Gračner first had the idea for the project years ago when she stumbled across an article about the lifting of the UK sugar rations and saw pictures of children flooding into bakeries when the restrictions ended.

By the time Gračner started her own research group and began piecing together a proposal with her colleagues to study the event, another tool had become available: the UK Biobank, a repository of genetic and medical data from half a million participants. After confirming that sugar intake had risen dramatically after the rations lifted, the team mined the biobank for people who had been conceived between October 1951 and June 1954, when the rations were in effect. They then compared the health of these people with the health of people who were conceived between July 1954 and March 1956, after the rations were removed.

Undeniable effect

The researchers found that the people conceived during the sugar limitations had a 35% lower risk of diabetes and a 20% lower risk of high blood pressure than people conceived after the rationing.

The magnitude of the effect is surprisingly large, says Duque. “It’s undeniable,” she says. “The big change here has to do with sugar.” Duque says that the results should add fuel to efforts to educate pregnant people about the importance of good nutrition.

Gračner agrees that education is crucial but doesn’t want anxious parents to overreact to her findings. “Pregnant people already have so much to worry about,” she says. “If it’s just a little sugar here and there, everybody’s going to be fine.”