A new study has found that a low-sugar diet in utero and in the first two years of life can meaningfully reduce the risk of chronic diseases in adulthood. This provides compelling new evidence of the lifelong health effects of early-life sugar consumption.

A study published in the journal Science reveals that children who had sugar restrictions during their first 1,000 days after conception faced up to a 35% lower risk of developing Type 2 diabetes and a 20% reduced risk of hypertension in adulthood. The research indicates that low sugar intake by mothers during pregnancy was sufficient to lower these health risks, and maintaining sugar restrictions after birth further enhanced the benefits.

Using 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 presents challenges,” explains Tadeja Gracner, a senior economist at the USC Dornsife Center for Economic and Social Research and the study’s corresponding author. “It is difficult to identify situations where individuals are randomly exposed to different nutritional environments early in life and tracked over a span of 50 to 60 years. The end of rationing provided us with a unique natural experiment that helped us overcome these obstacles.”

On average, during rationing, sugar intake was about 8 teaspoons (40 grams) per day. 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 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 no 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 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 later diagnosed with either of those conditions, the 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 researchers say the magnitude of this effect is meaningful as it can save costs, extend life expectancy, and, perhaps more importantly, improve quality of life.

In the United States, individuals with diabetes face average annual medical expenses of approximately $12,000. Additionally, an earlier diagnosis of diabetes is associated with a significantly reduced life expectancy; specifically, for each decade that diagnosis occurs earlier, life expectancy decreases by three to four years.

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

Experts continue to raise concerns about children’s long-term health as they consume excessive amounts of added sugars during their early life, a critical period of development. 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 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.