Low-Sugar Diet Early in Life Linked to 46% Lower Alzheimer’s Risk

Sweet foods can be offered as a reward from the earliest stages of life. Yet the sugar we consume before we can even speak may leave traces in our brains that last for decades.

These effects may even begin while we’re in the uterus, before our earliest memories are formed.

According to a new study published in npj Aging, babies exposed to less sugar before and after birth had lower risks of dementia, Alzheimer’s disease, depression, and anxiety later in life.

The findings don’t prove that consuming less sugar directly prevents these conditions. However, they suggest that nutrition during the first 1,000 days – from pregnancy until around a child’s second birthday – may leave lasting marks on the brain.

“The first 1,000 days – a critical window when the brain undergoes rapid development and is highly sensitive to nutritional cues.” – geriatric medicine researcher Bing Zhang

During and after World War II, sugar was strictly rationed in the UK. Adult allowances were close to current dietary recommendations, while children under two received no separate sugar allowance.

When rationing ended in September 1953, average adult sugar consumption nearly doubled, rising from around 41 to 80 grams per day. Children’s candy consumption more than doubled.

This abrupt shift created a rare natural experiment, allowing researchers to compare people who spent their earliest years under rationing with those born shortly after it ended.

Researchers in China analyzed health data from 60,394 UK Biobank participants born between 1951 and 1956.

Compared with people who were not exposed to rationing during early development, those whose first 1,000 days coincided with sugar restrictions had a 27 percent lower risk of developing dementia from any cause and a 46 percent lower risk of Alzheimer’s disease.

They also had an 11 percent lower risk of depression and a 20 percent lower risk of anxiety. No similar association was found for Parkinson’s disease.

The associations were strongest when rationing continued after birth. Exposure only in the uterus produced few clear differences, apart from a lower risk of anxiety.

The researchers also examined MRI scans from a subset of participants to see whether early sugar exposure was associated with detectable differences in the brain.

Those exposed to rationing after birth had brains that appeared, on average, 0.39 years younger than their chronological age. They also had larger volumes in several subcortical regions, including the hippocampus and thalamus, which are involved in memory and other cognitive functions.

“We believe the lasting protective effect is rooted in metabolic programming during the first 1,000 days – a critical window when the brain undergoes rapid development and is highly sensitive to nutritional cues,” senior author Bing Zhang, a geriatric medicine researcher at Guangzhou Medical University, told ScienceAlert.

The brain scans may provide another clue.

Zhang says the larger hippocampal and thalamic volumes associated with early sugar restriction could give the brain more capacity to withstand age-related changes.

A 2017 study published in Alzheimer’s & Dementia similarly linked higher consumption of sugary drinks with lower total brain volume and poorer episodic memory. Researchers analyzed cognitive data from 4,276 people and MRI scans from 3,846 participants, although the observational findings could not establish cause and effect.

Metabolic health and inflammation may also be involved.

“Early high sugar intake predisposes to insulin resistance and chronic low-grade inflammation, both of which are well-established risk factors for dementia,” Zhang explains.

These mechanisms were not directly tested in the study, however. The brain images were also captured at only one point in time, so they cannot establish that sugar restriction caused the structural differences.

Although this was not a randomized clinical trial, the researchers argue that the abrupt end of rationing offers stronger evidence than a conventional observational nutrition study.

“We are quite confident that sugar restriction itself is a major driver,” Zhang says.

The researchers also accounted for factors including birth location, socioeconomic status, and genetic background. Still, the end of rationing coincided with wider changes in postwar Britain.

Nor could the researchers determine how much sugar individual mothers and children actually consumed.

The UK Biobank also consists of a predominantly White and generally healthier volunteer population, which could limit how widely the findings apply.

Only 307 participants developed dementia during follow-up, including 123 diagnosed with Alzheimer’s disease, meaning the risk estimates were based on relatively small numbers of cases.

The study therefore does not prove that reducing sugar during pregnancy or infancy will prevent dementia decades later.

Related: Large Review Shows What Sugary Diets May Be Doing to Your Memory

Zhang acknowledges that “no single study can change official guidelines overnight,” but says the results support limiting added sugar during pregnancy and early childhood.

“This is not only about immediate health,” he says.

“It is a long-term investment in brain health decades later.”

The study was published in npj Aging

This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know.