Restricting sugar consumption in utero and in early childhood significantly reduces risk of midlife chronic disease

Published in Science, the study finds that children who experienced sugar restrictions during their first 1,000 days after conception had up to 35% lower risk of developing Type 2 diabetes and as much as 20% less risk of hypertension as adults. Low sugar intake by the mother prior to birth was enough to lower risks, but continued sugar restriction after birth increased the benefits.

Taking advantage of an unintended "natural experiment" from World War II, researchers at the USC Dornsife College of Letters, Arts and Sciences, McGill University in Montreal, and the University of California, Berkeley, examined how sugar rationing during the war influenced long-term health outcomes.

The United Kingdom introduced limits on sugar distribution in 1942 as part of its wartime food rationing program. Rationing ended in September 1953.

The researchers used contemporary data from the U.K. Biobank, a database of medical histories and genetic, lifestyle and other disease risk factors, to study the effect of those early-life sugar restrictions on health outcomes of adults conceived in the U.K. just before and after the end of wartime sugar rationing.

"Studying the long-term effects of added sugar on health is challenging," says study corresponding author Tadeja Gracner, senior economist at the USC Dornsife Center for Economic and Social Research. "It is hard to find situations where people are randomly exposed to different nutritional environments early in life and follow them for 50 to 60 years. The end of rationing provided us with a novel natural experiment to overcome these problems."

Sugar intake during rationing was about 8 teaspoons (40 grams) per day on average. When rationing ended, sugar and sweets consumption skyrocketed to about 16 teaspoons (80 grams) per day.

Notably, rationing did not involve extreme food deprivation overall. Diets generally appeared to have been, in fact, within today's guidelines set by the U.S. Department of Agriculture and the World Health Organization, which recommend no added sugars for children under two and not more than 12 teaspoons (50g) of added sugar daily for adults.

The immediate and large increase in sugar consumption but no other foods after rationing ended created an interesting natural experiment: Individuals were exposed to varying levels of sugar intake early in life, depending on whether they were conceived or born before or after September 1953. Those conceived or born just before the end of rationing experienced sugar-scarce conditions compared to those born just after who were born into a more sugar-rich environment.

The researchers then identified those born around this time in the U.K. Biobank data collected over 50 years later. Using a very tight birth window around the end of sugar rationing allowed the authors to compare midlife health outcomes of otherwise similar birth cohorts.

While living through the period of sugar restriction during the first 1,000 days of life substantially lowered the risk of developing diabetes and hypertension, for those who were later diagnosed with either of those conditions, onset of disease was delayed by four years and two years, respectively.

Notably, exposure to sugar restrictions in utero alone was enough to lower risks, but disease protection increased postnatally once solids were likely introduced.

The magnitude of this effect is meaningful as it can save costs, extend life expectancy and, perhaps more importantly, quality of life, say the researchers.

In the United States, people with diabetes incur annual medical expenditures of about $12,000 on average. Further, earlier diagnosis of diabetes means significantly shorter life expectancy, with every decade earlier that a diagnosis of diabetes is made cutting three to four years off of life expectancy.

These numbers underscore the value of early interventions that could delay or prevent this disease, the researchers note.

Experts' concerns about children's long-term health as they consume excessive amounts of added sugars during their early life, a critical period of development, continue to mount. Adjusting child sugar consumption, however, is not easy -- added sugar is everywhere, even in baby and toddler foods, and children are bombarded with TV ads for sugary snacks, say the researchers.

"Parents need information about what works, and this study provides some of the first causal evidence that reducing added sugar early in life is a powerful step towards improving children's health over their lifetimes," says study co-author Claire Boone of McGill University and the University of Chicago.

Co-author Paul Gertler of UC Berkeley and the National Bureau of Economics Research adds: "Sugar early in life is the new tobacco, and we should treat it as such by holding food companies accountable to reformulate baby foods with healthier options and regulate the marketing and tax sugary foods targeted at kids."

This study is the first of a larger research effort exploring how early-life sugar restrictions affected a broader set of economic and health outcomes in later adulthood, including education, wealth, and chronic inflammation, cognitive function and dementia.