Sugar rationing in the first 1,000 days tied to lower anxiety risk in adulthood

For children born in Britain in the early 1950s, how much sugar they got as babies depended on the calendar. Sugar was rationed after the Second World War, and the termination of UK sugar rationing in September 1953 meant that some babies spent their first two years on a restricted diet while others, born months later, did not.

A study in Translational Psychiatry, led by researchers at the University of Surrey, used that accident of timing to look at mental health decades later. Among 46,448 people, those rationed from conception to about age 2 were about a third less likely to have been diagnosed with anxiety.

What anxiety disorders are

Everyone feels anxious sometimes. Anxiety disorders are different: MedlinePlus describes them as conditions in which anxiety does not go away and can get worse over time. They include generalized anxiety disorder, panic disorder and phobias, and they are among the most common mental health conditions.

Their causes include genes, stress and life events. Researchers have also asked whether early nutrition plays a part, because the brain develops fastest in the first 1,000 days, from conception to a child’s second birthday.

How the sugar rationing natural experiment works

Most diet studies ask people what they eat and compare their health, which mixes diet up with everything else about their lives. Rationing is different. Nobody chose whether they were born before or after September 1953, so people born on either side of that date should be similar in most other ways.

The Surrey team used UK Biobank, a large study of middle-aged and older adults, and took people born between October 1951 and March 1956. Participants were grouped by duration of exposure to sugar rationing, from those rationed only in the womb to those rationed for about 1,000 days, and compared with people conceived after rationing ended. Anxiety and depression diagnoses came from linked health records.

What the Surrey sugar rationing study found

People rationed for about the first 1,000 days had reduced hazards of anxiety, about a third lower than people who were never rationed. They also had a lower risk of depression, but that link weakened once other factors were taken into account.

The anxiety result held up when the researchers checked it several ways, including adjustment for later-life sugar intake, so it was not simply explained by people eating less sugar as adults. The authors conclude that early rationing was associated with reduced risk of anxiety in adulthood.

“What we have found is that rationing of sugar in early life is linked to reduced sweet liking and lower risk of anxiety,” said Professor Nophar Geifman, the study’s senior author, in a university statement.

Brain scans and a taste for sugar

The team also looked at brain scans taken later in life. According to the university, 80 of the 139 brain regions they measured differed in gray matter volume between the rationing groups, and 11 differed between most rationed groups and people who were never rationed.

Sweet tastes differed too. The group rationed longest reported a slightly lower liking for sweet foods than people conceived after rationing, a small gap on the study’s scale. The researchers suggest early exposure may shape food preferences for life, although taste preference is one of many things that could link early diet to later health.

How it fits with other sugar rationing studies

This is the fourth analysis of the same natural experiment published this year to look at mental health, and they point the same way. A study in Molecular Psychiatry of 64,381 people found that those rationed in the womb and up to age 2 had a 23% lower hazard of anxiety and 17% lower for depression, a result we covered in an earlier article. A General Psychiatry analysis found rationing delayed the first diagnosis by approximately 2 years for anxiety. An npj Aging study reported lower risks of dementia and anxiety, with the anxiety risk 20% lower.

That agreement is less independent than it looks. All four drew mainly on UK Biobank participants born in the same years, so they are largely different analyses of the same people. The Molecular Psychiatry team added a stronger check: similar inverse associations were observed in the English Longitudinal Study of Ageing, a separate cohort, but not in a US study of people who never lived under British rationing.

What the sugar rationing studies cannot show

Rationing was not a controlled trial. Babies born before and after 1953 also grew up as other foods came off ration and postwar Britain changed, so sugar may not be the only difference between the groups. Nobody’s infant diet was actually measured; exposure is inferred from birth dates.

UK Biobank volunteers are healthier and better off than the population as a whole, and anxiety counts only when it was diagnosed and recorded. The brain scan findings come from the press release, and differences in brain volume say nothing on their own about whether a person feels anxious.

What guidelines say about sugar

The study does not test any advice, and current guidance does not rest on it. The World Health Organization (WHO) recommends keeping free sugars below 10% of daily energy for adults and children, and adds that a further reduction to below 5% or roughly 25 grams (6 teaspoons) per day would provide additional health benefits. That guidance is based on weight and tooth decay rather than mental health.

“Knowing the full impact that sugar can have on our physical and mental health, across our lifespan, could help inform public health policy and reshape our diets,” said Dr Hana Navratilova, who led the work at Surrey.