From milkshakes to soda, cookies to donuts—modern life is undeniably sweet. But can this lifestyle affect the brain even before birth?
The health risks of a high-sugar diet are well known: obesity, Type 2 diabetes, heart disease and more. But new research from Dr. Kiran Soma’s lab at UBC suggests the effects may start even earlier.
In a recent study published in the Journal of Endocrinology, pregnant rats consumed sucrose (table sugar) making up about 26 per cent of their daily calories— on par with some sugar-packed human diets. The research team found that this diet triggered hormonal changes in the fetus that could influence brain function and behaviour later in life.
“During early development, the brain is particularly impressionable,” Dr. Soma explains. “The results of our study show that sucrose exposure might have large, long-lasting effects on the brain and behaviour.”
Hidden Stress Signals
While past studies have focused mostly on corticosterone, the primary stress hormone in rodents, the study by Dr. Soma’s team, funded by the Canadian Institutes of Health Research, takes a broader look. “We used advanced mass spectrometry techniques to measure many steroids at once, and therefore were able to detect these changes,” notes Michelle Jung, coauthor and PhD student in the Soma Lab. “If we just measured corticosterone, we would have missed critical information.” Although corticosterone was not yet affected at this developmental stage, the hormonal environment was already shifting.
“We saw alterations in the precursors and metabolites of corticosterone,” explains lead author Dr. Désirée Seib, a former postdoctoral research fellow in the Soma lab. “It seems there is stress in the mom and fetuses, but their bodies are able to stay in balance by diverting the increased stress away from corticosterone.”
One sign of this internal stress regulation was an increase in a compound called DHC in the amniotic fluid. The placenta seems to have been working overtime to convert excess corticosterone into a less harmful form and protect the fetus from the effects of stress. Also, the research team found that sucrose-fed mothers had smaller placental sizes, which could compromise both fetal protection and hormone production.
Sugar, Aldosterone and the Developing Brain
Another unexpected finding was the elevated levels of aldosterone in the fetal brain. Typically, this hormone is known for its role in regulating blood pressure and electrolyte balance. However, earlier human studies have linked heightened aldosterone to depression, a condition often associated with chronic stress.
“Our study indicates that the body may respond to stress by increasing aldosterone in early life,” explains Dr. Seib, currently an Assistant Professor at the University of Prince Edward Island. “Aldosterone also acts on microglia, the brain’s resident immune cells that play an important role in proper brain development.”
These findings add to growing evidence that increases in aldosterone may influence brain development and affect stress-related behaviours.
Changing the Brain’s Reward Circuitry
Elevated levels of sucrose can also affect brain systems involved in reward, increasing preferences for sucrose and other addictive substances like alcohol or other drugs. In a previous study published by the Soma lab, researchers found that a high-sucrose diet in rat mothers led to a number of behavioural effects on their adult offspring.
“Results showed that the male offspring had an increased preference for sugary and fatty foods,” Dr. Seib recalls. “In an operant conditioning task, they worked harder for sugar rewards when compared to the control group.”
The present study found that these differences may be related to androgens – “male” sex hormones – which were lower in the nucleus accumbens of these offspring. The nucleus accumbens is heavily involved in motivation and reward, and these subtle changes might affect food preference and motivation.
In humans, high sugar intake can also lead to stronger cravings for unhealthy foods and might even increase drug-seeking behaviours such as smoking.
Sex Differences Start Early
Interestingly, the previous study found that the effects of maternal sucrose consumption differed by sex. Adult female offspring were more affected in terms of stress hormone levels, while adult males showed greater changes in reward-seeking behaviour.
“There could be an interplay between stress and sex hormones like androgens and estrogens, resulting in these variations in response to stress and reward,” Dr. Seib says.
Different brain regions regulate these systems, and they may respond to hormonal changes in sex-specific ways, highlighting the importance of inclusive research.
Sugar vs. Stress: More Similar Than You Think?
This study adds to a growing body of evidence suggesting that a sugary maternal diet can influence offspring in ways mirroring maternal stress.
“There are some similarities between the effects of maternal stress and maternal high-sucrose diet,” Dr. Soma explains. “Both increase stress hormone levels in the mother and both have long-lasting, sex-specific effects on the offspring.”
Maternal stress during pregnancy is known to alter fetal brain development, increasing the risk of mood disorders, cognitive changes and other neurodevelopmental conditions in children. It’s a striking idea: that something as routine as consuming extra sugar might trigger similar hormonal disruptions—with similarly lasting consequences.
Implications for Humans
During World War II, sugar rationing by the United Kingdom cut down sugar intake in pregnant women. Remarkably, a study published in Science found that those exposed to sugar restrictions in the womb and during early life were much healthier, with delayed disease onset.
- 35 per cent lower risk of type 2 diabetes
- 20 per cent lower risk of hypertension
While Dr. Soma’s research is primarily with rat models, it still carries important implications for human health – understanding the details of how sucrose affects the developing brain will help us improve the health of the next generation.
What’s Next?
Future studies in the Soma lab will examine which component of sucrose – glucose or fructose – handles these hormonal changes.
Michelle is also investigating the generational effects of sucrose consumption.
“By continuing to feed offspring with a high-sucrose diet throughout adolescence, I’m investigating whether the combination of both maternal and offspring high-sucrose intake further alters hormones and behaviour in adulthood,” she explains.
There’s also growing interest in how these hormone shifts affect microglia in the brain, and how changes in early life may set the stage for behavioural differences observed later on.
The takeaway? Sugar doesn’t just sweeten your food. It could also leave a lasting imprint on the developing brain.
This feature was originally posted on the Djavad Mowafaghian Centre for Brain Health’s website.