Sugar exposure during the first 1,000 days after conception is linked with type 2 diabetes and hypertension later in life, according to a new study.
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Limiting sugar during the first 1,000 days after conception—the period including pregnancy and the two years after birth—may reduce a child’s risk of diabetes and hypertension in adulthood.
Scientists reached this conclusion, detailed last week in the journal Science, after studying the effects of sugar rationing in the United Kingdom during World War II.
Researchers and public health practitioners have long wondered how a person’s fetal and childhood nutrition might affect their health later in life. But accurately measuring any such connection is challenging, because it’s difficult to design randomized, controlled experiments that are ethical, feasible and fine-tuned enough to test for causation. For example, researchers can’t force groups of mothers to feed their babies different diets, then follow those babies into adulthood to see how they fare.
But scientists came up with a clever workaround to these hurdles. They used the conditions of World War II to set up a “natural experiment” that evaluated differences between people conceived and born during and after sugar rationing.
In January 1940, the British government began rationing certain foods, including sugar. Adults were limited to roughly 40 grams of sugar per day. After sugar rationing ended in September 1953, people began consuming roughly twice the amount of sugar they ate during rationing, with adults eating around 80 grams daily.
To understand the effects of sugar rationing on human health, researchers turned to a large biomedical database called the UK Biobank. They analyzed the health records of roughly 60,000 adults born between October 1951 and March 1956—some who were conceived during rationing, and some who were conceived after rationing ended. The two groups were similar in terms of race, sex and levels of family history of type 2 diabetes and heart disease—meaning the main difference was how much sugar they were exposed to during the first 1,000 days after conception.
Across all the participants, more than 3,900 became diagnosed with type 2 diabetes and 19,600 became diagnosed with hypertension (high blood pressure). But the prevalence and age of onset for these conditions were different across the two groups.
Those who were conceived during rationing were 35 percent less likely to develop type 2 diabetes and 20 percent less likely to develop hypertension, with the largest differences seen after they reached their mid-60s. If they did develop either condition, it happened later in their lives compared to those conceived after rationing—four years later, on average, for type 2 diabetes, and two years later, on average, for hypertension.
Those who were conceived and born during sugar rationing had the lowest risk of developing either disease. Those who were conceived during sugar rationing, but born after rationing ended, were at greater risk of developing the conditions. This demonstrates what’s known as a “dose-response relationship,” reports Science’s Catherine Offord. The longer babies spent under sugar rationing, the lower their risk for disease later in life.
“It’s a really exciting analysis,” Jack Bowden, a biostatistician at the University of Exeter in England who was not involved with the study, tells Science.
The results align with past research that has found connections between sugar consumption and chronic diseases. But the protective effects of sugar rationing were significant—similar to quitting smoking or a lifelong adherence to a vegetarian diet, reports Popular Science’s Lauren Leffer.
“What we found is, in one sense, not that surprising, because we already had a lot of knowledge about the association between sugar and poor health outcomes,” study co-author Claire Boone, a health economist at McGill University in Canada, tells Popular Science. “But the magnitude of our findings were kind of surprising.
Researchers were able to pinpoint sugar as the likely culprit behind these differences, because the amount and proportion of other foods in people’s diets didn’t change much during and after rationing. They also found no links between rationing and health conditions that aren’t related to diet, such as type 1 diabetes, which is mainly genetic, and nearsightedness. This suggests that people conceived or born during rationing were just as healthy overall as those born after, and they were not simply more likely to be diagnosed with any health condition.
But how and why did sugar make such a big impact? The study wasn’t designed to answer that question, but researchers have come up with a few hypotheses. One possible explanation is that exposure to sugar early on can give people more of a sweet tooth, leading them to consume more sugar later in their lives.
“Studies show that—while most humans like sweet—significant sugar exposure in early life can strengthen this preference,” study co-author Tadeja Gračner, an economist at the University of Southern California, tells the BBC’s James Gallagher.
Another possibility is that exposure to sugar in the womb affects fetal development in some way that makes a person more susceptible to diseases related to processing nutrients. People also ate fewer overall calories as they consumed less sugar during rationing. The difference between 40 and 80 grams of sugar is roughly 155 calories, per the New York Times’ Gina Kolata.
Still, other factors might have been at play.
“It may be that at the same time rationing ended and people consumed more sugar, they also changed other habits becoming, for example, less physically active,” says Amanda Adler, a doctor and health policy expert at the University of Oxford in England who was not involved with the research, to the Telegraph’s Sarah Knapton.
Whatever the explanation, the findings suggest that parents should limit sugar consumption during pregnancy and in a baby’s first few years of life, the researchers say. That doesn’t necessarily mean cutting out sugar entirely, but just being more mindful and sticking closer to the recommended levels. Scientists add that parents should not be blamed or shamed for feeding their kids sugar snacks periodically.
“I don’t want parents to be feeling guilty for giving their toddlers sugar sometimes,” says Gračner to Science News’ Skyler Ware.
She adds: “We all want to improve our health and give our children the best [start in] life… The takeaway is that reducing added sugar early is one of the powerful steps in that direction.”
