From the earliest stages of life, sweet foods can serve as rewards. However, the sugar consumed in infancy might leave lasting imprints on the brain. These effects might even begin in the womb, before memory formation.
A study in npj Aging suggests that reduced sugar exposure before and after birth correlates with lower risks of dementia, Alzheimer’s disease, depression, and anxiety later in life.
While the study does not confirm that less sugar directly prevents these conditions, it indicates that nutrition during the first 1,000 days—from pregnancy to a child’s second birthday—can have enduring effects on brain health.
“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, the UK imposed strict sugar rationing. Adult allowances were near current dietary guidelines, and children under two had no separate sugar allowance.
When rationing ended in September 1953, adult sugar intake nearly doubled from about 41 to 80 grams daily, and children’s candy consumption more than doubled.
This sudden change provided a unique opportunity to compare individuals who grew up during rationing with those born just after it ended.
Researchers in China studied health data from 60,394 UK Biobank participants born between 1951 and 1956.
Those whose first 1,000 days occurred during sugar rationing had a 27% lower risk of developing dementia and a 46% lower risk of Alzheimer’s disease compared to those not exposed to rationing. They also had an 11% lower risk of depression and a 20% lower risk of anxiety. No similar link was found for Parkinson’s disease.
The strongest associations were observed when rationing continued after birth. Exposure only during pregnancy showed fewer differences, except for a reduced risk of anxiety.
Researchers also analyzed MRI scans from some participants to check for brain differences linked to early sugar exposure.
Participants exposed to rationing after birth had brains appearing on average 0.39 years younger than their actual age. They also had larger volumes in subcortical areas like the hippocampus and thalamus, crucial for memory and 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,” Bing Zhang, a geriatric medicine researcher at Guangzhou Medical University, stated to ScienceAlert.
The brain scans might offer further insight.
Zhang suggests that larger hippocampal and thalamic volumes from early sugar restriction may help the brain handle age-related changes.
A 2017 study in Alzheimer’s & Dementia also connected high sugary drink intake with reduced brain volume and poorer episodic memory. Researchers reviewed cognitive data from 4,276 people and MRI scans from 3,846 participants, but the observational results couldn’t establish a cause-and-effect relationship.
Metabolic health and inflammation may also play a role.
“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 weren’t tested directly in the study. The brain images, captured at one point in time, can’t confirm that sugar restriction caused the structural differences.
Though not a randomized clinical trial, researchers argue that the sudden end of rationing provides stronger evidence than traditional observational studies.
“We are quite confident that sugar restriction itself is a major driver,” Zhang says.
The study considered factors like birth location, socioeconomic status, and genetic background. Still, the end of rationing coincided with broader postwar changes in Britain.
Researchers couldn’t determine individual sugar intake for mothers and children.
The UK Biobank primarily includes a predominantly White, generally healthier population, which might limit the findings’ applicability.
Only 307 participants developed dementia during follow-up, with 123 diagnosed with Alzheimer’s, so risk estimates are based on relatively small case numbers.
Thus, the study doesn’t 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 suggests the results support limiting added sugar during pregnancy and childhood.
“This is not only about immediate health,” he adds.
“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.
