May is Mental Health Month and I’ve been getting questions about food’s effect on mental health, especially junk food. One common question is , “ Do diet drinks affect the brain and cause depression?” Yes. In particular, the artificial sweetener aspartame , found in diet soda, is often blame d . Aspartame has been studied for its potential effects on the nervous system, including mood . Unfortunately, two studies have found that drinking aspartame-containing beverages increased risk of depression and one study also worsened symptoms in those who already had diagnosed depression . If aspartame causes depression, why do you say, "Everything in moderation?" One single can of diet soda doesn't cause depression. One teaspoon of aspartame in your tea or coffee doesn't cause your existing depression to worsen. Even one can of soda a day in addition to one teaspoon of aspartame add...