Britain’s hardships during World War II famously included weeks of bombing during the Blitz, the mass evacuation of children, and food rationing. That rationing, researchers report, holds cautionary lessons for today on the health impact of consuming sugar early in life.
Black-and-white wartime photos capture long queues in the shops when supplies of meat, dairy, sugar, and other food were limited. Rationing began in 1940 but lasted long after peace was declared in 1945.
Restrictions on sugar ended in September 1953, a perfect turning point for a natural experiment in nutrition before and after birth. Pregnant mothers and children had fewer sweet foods to eat before rationing expired, but almost immediately after restrictions ended, sugar consumption nearly doubled, from 41 grams to 80 grams per day. The daily ration for sugar had been the equivalent of about 6 to 7 teaspoons of sugar, an amount comparable to today’s dietary guidelines from the World Health Organization, which say sugars should equal no more than 10% of total calories.
Did the health of children conceived just before and just after that cusp differ later in life?
Decades later, researchers have seized on that moment, impossible to recreate in a randomized clinical trial, to compare the impact of sugar during pregnancy and up to the first two years of life, before and after this inflection point. Those 1,000 days revealed significant differences between the two groups, based on their health data held in the U.K. Biobank.
The group of children who consumed less sugar in the womb or into toddlerhood had a 35% lower risk of type 2 diabetes and a 20% lower risk of hypertension than those who had more sugar before and after birth. If people in the earlier cohort developed these conditions, they did so at an older age: four years later for type 2 diabetes and two years later for hypertension, the study published Thursday in Science found. Less exposure to sugar during pregnancy was tied to one-third of the reduced risk of diabetes and hypertension, with another drop in relative risk at six months of age, a time the authors linked to kids’ first solid foods.
Among the more than 60,000 people studied, nearly 4,000 developed type 2 diabetes and almost 20,000 had hypertension. Risk for these conditions rose with age, but not as fast for those who experienced sugar rationing. (Rationing for butter ended in May 1954 and for all foods in July 1954.) Obesity was 30% lower in the sugar-rationed group. People conceived after rationing ended continued to eat more sugar into their 60s, the study said.
What does this study, which happened to be released on the candy-intense holiday of Halloween, mean for children today?
“This is a very good and interesting study that very nicely exploits a natural history experiment. Since it is essentially an uncontrolled cohort study, I don’t think they conclusively demonstrate causality,” Bob Siegel, director of the Center for Better Health and Nutrition at Cincinnati Children’s Hospital, told STAT. He was not part of the research. “My own opinion is that limiting sugar is a good idea. It adds to the overwhelming evidence that sugar consumption is just plain not good for you.”
Study author Tadeja Gracner, a health economist at the Center for Economic and Social Research at the University of Southern California, pointed out that the environment in the study — 1950s Britain — wasn’t the extreme food deprivation you’d find in a famine. Sugar wasn’t banned; it was rationed to what experts now see as a healthy amount. Disease onset was delayed, but not eliminated.
“We don’t say, eat less sugar and you’re never going to have disease,” Gracner said in an interview. “We’re saying you’re probably going to get a few extra years without it, which is pretty valuable.”
The researchers tried to account for other factors affecting the groups born within a few months of each other. Fruit and vegetable consumption remained flat before and after rationing, for example. Diagnoses of type 1 diabetes, which is not related to diet, also remained stable. They also acknowledge that the Biobank cohort is not representative of the U.K. population because it tends to be white as well as healthier and wealthier.
This study has inspired other research on when food preferences are formed and how they affect health, Gracner said. Her working paper, posted by the National Bureau of Economic Research but not peer-reviewed, explores that issue. How much of a sweet tooth you develop may depend on your exposure, Gracner said, and that preference develops early.
“We find that a sugar-rich diet early in life elevated free sugar consumption across lifespan, consistent with evidence that life-long dietary preferences and habits form early, and that sugar may be addictive,” the working paper says.
Caroline Apovian, an endocrinologist who co-directs the Center for Weight Management and Wellness at Brigham and Women’s Hospital, sounded a similar theme, linking early preferences to the high prevalence of obesity among children in the U.S.
“This study really gets me very excited because it just basically says, my God, if you’re exposed in utero to sugar, years later you develop more diabetes,” she told STAT. She was not involved in the research. “We’ve got so much more ultra-processed food now than then. If we acquire the taste, let’s say, to eat high-sugar food, then that may be indicative of all of the cravings, not just for sugar but salty food and all the ultra-processed foods that we’re eating.”
Apovian lamented the omnipresence of ultra-processed foods and also who is most affected by their availability. It’s not preference as much as the environment, she said.
“The prevalence of obesity has really most affected those people in the United States in the lowest socioeconomic class,” she said. “We know that there are food deserts. They can’t go to Whole Foods and get their fruits and vegetables because it’s too expensive, it’s not around. ”
While Gracner’s research underscores the importance of early life intervention in nutrition, she does not want to blame pregnant women or parents.
“I want to stress that it is extremely hard to eat healthy, with the abundance of added sugar around,” she said. “This shouldn’t be about, pregnant women shouldn’t eat croissants anymore.”
Amanda Adler, a professor of diabetic medicine and health policy from the University of Oxford, called it “intriguing and entirely possible” that lower exposure to sugar before birth might lead to life-long health benefits.
“This study is an open invitation to clinical trialists to clarify the ‘right’ levels of sugar to add to the diet for pregnant or lactating women, and for their infants,” she said in a statement posted by the Science Media Centre.
Grancer hopes to examine the question in other pathways: epigenetics, gut health and the microbiome, who is getting affected and when.
“There’s so much to understand.”
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