Those prone to depression may do well to avoid high-sugar treats this holiday season. New research by a team of clinical psychologists at the University of Kansas (KU) found that consuming foods with a high ratio of added sugars can trigger metabolic, inflammatory, and neurobiological processes linked to major depressive illnesses. The findings are published in the online journal Medical Hypotheses.
Seasonal Depression Disorder (SAD) is a tale we all know too well, having become so ubiquitous in Western society that most people approach the prospect of winter-time depression with an acerbic acceptance — an unavoidable cross to bear (for those who choose to live on the Northern Hemisphere).
“For many people, reduced sunlight exposure during the winter will throw off circadian rhythms, disrupting healthy sleep and pushing 5% to 10% of the population into a full-blown episode of clinical depression,” said Ilardi.
The lack of light that leads to SAD induced depression is also what incites people to crave sweets. It’s a pretty vicious Catch 22 — the less access to light, the more depressed the individual, and the more likely that individual is to crave sugary sweets that only exacerbate the feelings of depression, compounding the cycle of unhealthy habits.
A Western propensity
Ironically, the privilege afforded by living a developed, high-calorie consuming Western country also poses a challenge for those who have access to high-calorie foods.
It’s estimated that Americans derive “14% of all calories from supplementary sugars,” the researchers said. To put this into perspective, that’s the equivalent of consuming “18 teaspoons a day.” Before you exempt yourself from the data, bear in mind that most of this consumption is involuntarily made — sweeteners are even found in an estimated 75% of all packaged foods. Luckily, the transparency of nutrition labels makes moderating sugar intake easier.
“U.S. dietary guidelines now advise limiting the consumption of added sugars, both to promote better overall health and to help reduce the burgeoning toll of obesity,” the researchers asserted.
An inflamed brain is a depressed brain
To conduct the study, the researchers considered a thorough array of findings on the adverse health effects of consuming added sugar, including the Women’s Health Initiative Observational Study, the NIH-AARP Diet and Health Study, and studies of Australian and Chinese soda-drinkers. Qualifying this collection of data, they discovered inflammation to be the most significant physiological agitator of sugar-related depressive disorder.
“Elevated systemic inflammation is recognized as a potent physiological trigger of depression…added sugars have a profound effect on inflammatory processes within the body and brain, and inflammation may serve as a key mediator of sugar-induced depression onset,” they posited.
In addition, the studies also identified four other depressive physiological byways affected by sugar intake. “… disruption of the gut-brain axis, oxidative stress, insulin resistance, and the production of toxic advanced glycation end products (AGEs)—are also associated with increased inflammation.” Our body hosts millions of microbes that our physiologically beneficial, but, according to Ilardi, there are certain “parasitic microbes” that exacerbate stress and anxiety in the brain.
“They’re also highly inflammatory,” said Ilardi.
Breaking the sweets cycle
There’s no doubt that food-contingent depression is more pervasive during the holiday season. But, by evidencing that holiday depression an environmental factor, the findings actually allow for a more sunny conclusion: depressive symptoms can be controlled.
“…healthy and unhealthy diets, respectively, each appear to exert independent effects on mental health, which suggests that depressogenic processes can be affected both by the relative absence of key nutrients and by the excessive presence of harmful food,” said Ilardi.
This offers some semblance of control for those who struggle with seasonal depression, though moderation can be challenging during the wintertime when tempting sweets are abounding.
In these exceptional cases, Ilardi allows for some realistic leniency. “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,” he said. But, if you need a hard figure to stand by in the wake of the approaching holiday festivities, Ilardi recommends sticking to the American Heart Association guidelines, which is 25 g of added sugars per day.
Unfortunately for those who hope to circumvent the negative effects of pastries for a boozy alternative, the same rules apply. “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,” said Ilardi.
The researchers posit that their findings on the correlation between dietary sugar and depression not conclusive. While the findings are “persuasive,” Ilardi concedes that “rigorous experimental manipulations of added sugar intake” are still necessary on a larger, more diverse group of people. Nonetheless, the evidence thus far is one of many pieces of evidence that underline the link between diet and mental health.