Several studies have linked excess consumption of added sugar (not the natural sugars in foods such as milk and fruit) to depression. However, they didn’t resolve whether eating too much added sugar causes depression, or if depression leads to craving more sweets. A longer study published in Scientific Reports supports the idea that the culprit is too much sugar, at least in men.
The study used questionnaires to track the diets and health of more than 8,000 people in the United Kingdom, collecting data multiple times over a 22-year period. Compared with men who consumed the least sugar (less than 39.5 grams a day) from sweets such as cake, cookies, and soda, men who consumed the most (at least 67 grams a day) were 23 percent more likely to have symptoms of depression, anxiety, or other common mood disorders over a five-year period. For perspective, a 12-ounce can of soda contains about 40 grams of sugar.
No association was seen in women, however, perhaps because of their smaller number in the study, gender differences in depression pathology, or chance.
Previous studies have suggested that habitual sugar consumption may cause inflammation and other biological changes that can lead to depression. This study, which was published in 2017, doesn’t prove that added sugar causes depression. Nevertheless, it’s a good idea to reduce sugar intake for a variety of health reasons. Less than 10 percent of calories should come from added sugars, according to U.S. dietary guidelines.