If you’re prone to the holiday season blues (depression), a study published in the journal Medical Hypotheses suggests that this holiday season you might want to say “bah humbug” to offers of sugar plum pudding, caramel corn, and chocolate babka. A team of clinical psychologists at the University of Kansas suggests eating added sugars, which are so very common in so many holiday foods, can trigger metabolic, inflammatory, and neurobiological processes tied to depressive illness.
Creating the “perfect storm”
When you pair the added sugar with less light during wintertime as well as the corresponding changes in sleep patterns, high sugar consumption could result in a “perfect storm” that adversely affects mental health, according to the researchers.
“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, KU associate professor of clinical psychology.
Ilardi, who co-authored the study with KU graduate students Daniel Reis (lead author), Michael Namekata, Erik Wing, and Carina Fowler (now of Duke University), said these symptoms of “winter-onset depression” could prompt people to consume 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.”
Avoiding add sugar can be difficult
However, the researchers believed that avoiding added dietary sugar might be especially challenging because sugar offers an initial mood boost, leading some with depressive illnesses to seek its temporary emotional lift during this, “the most wonderful time of the year”.
“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.”
Researchers reached their conclusions by analyzing a range of studies investigating 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.
The team cautioned it might be appropriate to view added sugar, at high enough levels, as physically and psychologically harmful, akin to drinking a little too much liquor.
“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.”
Systemic inflammation
Their analysis revealed that inflammation is the most important physiological effect of dietary sugar related to mental health and depressive disorder and that sugar’s impact on the microbiome may also be a potential contributor to depression.
“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.”
“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 into a state of anxiety, stress, and depression. They’re also highly inflammatory.”
To avoid seasonal blues the team recommends trying to stick to a minimally processed diet rich in plant-based foods and Omega-3 fatty acids for optimal psychological benefit. But when it comes to added sugars, the researchers suggest that we use caution not just during the holidays, but all 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.”
