We're becoming increasingly aware of sugar's negative effects on the body. But we still tend to think of them as physical effects, such as increased risk for diabetes and obesity. A connection between sugar and poor mental health might seem counterintuitive—especially given how much Americans seem to like comforting themselves with sweet food. A new study, however, found that men who consume high levels of sugar are more likely to develop depression or anxiety compared to those with low-sugar diets.
The findings come from an analysis by researchers at University College London of questionnaires submitted by more than 5,000 men and 2,000 women in the United Kingdom from 1983 to 2013. Participants reported on their diet and lifestyle, including surveys about their mental health and information about their weight and height.
Researchers used the reports to estimate how much sugar people were eating daily; the top third of participants were consuming more than 67 grams of added sugar, while the bottom third consumed less than 39.5 grams. (There are about 4 grams of sugar in one teaspoon.) According to the National Diet and Nutrition Survey published in 2013, men in the UK get about 75 percent of that added sugar from sweet foods and beverages.
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Previous studies had shown a link between sugar consumption and depression. But knowing there's a link only takes you so far; it doesn't prove causation. Do people who feel depressed eat more sugar, or does their sugar intake actually affect their mental state, leading to mood disorders such as anxiety and depression? That's one question researchers hoped to clarify.
"Sweet food has been found to induce positive feelings in the short-term. People experiencing low mood may eat sugary foods in the hope of alleviating negative feelings," Anika Knüppel, the paper's lead author, said in a statement. "Our study suggests a high intake of sugary foods is more likely to have the opposite effect on mental health in the long-term."
Using the data, researchers found that men among the top third for sugar consumption were 23 percent more likely to experience depression or anxiety over the next five years. That's after controlling for factors such as general health and socio-economic status. Interestingly, women did not show the same pattern, and researchers aren't yet clear why. But researchers did not find that men and women with mood disorders were more likely to consume sugar, strengthening the other possibility: that sugar does affect mental health.
"High sugar diets have a number of influences on our health but our study shows that there might also be a link between sugar and mood disorders, particularly among men," Knüppel added. "There are numerous factors that influence chances for mood disorders, but having a diet high in sugary foods and drinks might be the straw that breaks the camel's back." She also called for more research into the connection among a broader population.
The study arrives as governments around the world look for ways to curb sugar consumption. Canada's Northwest Territory is considering a sugar tax, and the UK already has a tax on sugary soft drinks set to go into effect next April. In the United States, as always, things are more complex: Berkeley, California, taxes sugar-sweetened beverages, with several other cities looking to follow its lead, but the sugar industry has lobbied the FDA to delay nutrition labels that would include a separate line about added sugars.
At the very least, the new study suggests that decreasing your sugar intake isn't just good for your body—it may just be good for your mind, too.
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