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Study: To Help Avoid Winter-Time Depression, Skip the Sweet Treats

If you’re prone to depression, you might want to avoid indulging in sweet treats this holiday season.

A new study, published in the journal Medical Hypotheses, suggests that eating added sugars can trigger metabolic, inflammatory and neurobiological processes tied to depressive illness.

Together with dwindling light in wintertime and corresponding changes in sleep patterns, high sugar consumption could result in the “perfect storm” for poor mental health.

“For many people, reduced sunlight exposure during the winter will throw off circadian rhythms, disrupting healthy sleep and pushing five to 10% of the population into a full-blown episode of clinical depression,” said Stephen Ilardi, an associate professor of clinical psychology at the University of Kansas.

Ilardi said these symptoms of “winter-onset depression” could prompt people to eat more sweets.

“One common characteristic of winter-onset depression is craving sugar,” he said. “So, we’ve got up to 30% of the population suffering from at least some symptoms of winter-onset depression, causing them to crave carbs — and now they’re constantly confronted with holiday sweets.”

Ilardi said avoidance of added dietary sugar might be especially challenging because sugar offers an initial mood boost, leading some with depressive illness to seek its temporary emotional lift.

“When we consume sweets, they act like a drug,” said the KU researcher, who also is author of “The Depression Cure” (First De Capo Press, 2009). “They have an immediate mood-elevating effect, but in high doses they can also have a paradoxical, pernicious longer-term consequence of making mood worse, reducing well-being, elevating inflammation and causing weight gain.”

For the study, the research team analyzed a wide range of research on the physiological and psychological effects of consuming added sugar, including the Women’s Health Initiative Observational Study, the NIH-AARP Diet and Health Study, a study of Spanish university graduates, and studies of Australian and Chinese soda-drinkers.

Ilardi says it might be appropriate to view added sugar, at high enough levels, as physically and psychologically harmful, similar to drinking a little too much alcohol.

“We have pretty good evidence that one alcoholic drink a day is safe, and it might have beneficial effect for some people,” he said. “Alcohol is basically pure calories, pure energy, non-nutritive and super toxic at high doses. Sugars are very similar. We’re learning when it comes to depression, people who optimize their diet should provide all the nutrients the brain needs and mostly avoid these potential toxins.”

The researchers found inflammation is the most important physiological effect of dietary sugar related to mental health and depressive disorder.

“A large subset of people with depression have high levels of systemic inflammation,” said Ilardi. “When we think about inflammatory disease we think about things like diabetes and rheumatoid arthritis — diseases with a high level of systemic inflammation.”

“We don’t normally think about depression being in that category, but it turns out that it really is — not for everyone who’s depressed, but for about half. We also know that inflammatory hormones can directly push the brain into a state of severe depression. So, an inflamed brain is typically a depressed brain. And added sugars have a pro-inflammatory effect on the body and brain.”

In addition, the researchers identify sugar’s impact on the microbiome as a potential contributor to depression.

“Our bodies host over 10 trillion microbes and many of them know how to hack into the brain,” Ilardi said. “The symbiotic microbial species, the beneficial microbes, basically hack the brain to enhance our well-being. They want us to thrive so they can thrive.”

“But there are also some opportunistic species that can be thought of as more purely parasitic – they don’t have our best interest in mind at all. Many of those parasitic microbes thrive on added sugars, and they can produce chemicals that push the brain in a state of anxiety and stress and depression. They’re also highly inflammatory.”

Ilardi recommends a minimally processed diet rich in plant-based foods and Omega-3 fatty acids for optimal psychological benefit. As for sugar, he recommends caution — not just during the holidays, but year-round.

“There’s no one-size-fits-all approach to predicting exactly how any person’s body will react to any given food at any given dose,” Ilardi stated. “As a conservative guideline, based on our current state of knowledge, there could be some risk associated with high-dose sugar intake — probably anything above the American Heart Association guideline, which is 25 grams of added sugars per day.”

Ilardi coauthored the study with KU graduate students Daniel Reis (lead author), Michael Namekata, Erik Wing and Carina Fowler (now of Duke University).

Source: University of Kansas

Study: To Help Avoid Winter-Time Depression, Skip the Sweet Treats

Traci Pedersen

Traci Pedersen is a professional writer with over a decade of experience. Her work consists of writing for both print and online publishers in a variety of genres including science chapter books, college and career articles, and elementary school curriculum.

APA Reference
Pedersen, T. (2019). Study: To Help Avoid Winter-Time Depression, Skip the Sweet Treats. Psych Central. Retrieved on November 30, 2020, from
Scientifically Reviewed
Last updated: 27 Dec 2019 (Originally: 27 Dec 2019)
Last reviewed: By a member of our scientific advisory board on 27 Dec 2019
Published on Psych All rights reserved.