Why Might Eating Too Much Chocolate Lead to Clinical Depression?

Another piece of evidence has been found regarding the harm caused by excessive sugar consumption: Joining the series of studies pointing to the link between sugar intake and obesity, diabetes, or heart disease, a new study has found a connection between excessive sugar consumption and mental health.

In a study that followed 8,000 adults for 22 years, researchers from University College London found that men who reported consuming foods containing 67 grams of sugar a day had a 23 percent higher risk of being diagnosed with clinical depression five years after the study began.

For the study, researchers examined a group of adults who participated in the Whitehall II study, a longitudinal study that followed data regarding the health and stress levels of civil servants aged 35 to 55. Every few years, participants filled out questionnaires about their diet and other health markers, including whether they were diagnosed with or without depression and anxiety. All participants began the study as mentally healthy individuals without any diagnosed mental health issues.

Five years after the beginning of the study, researchers found that those who consumed 67 grams or more of sugar per day—more than twice the maximum daily amount according to the American Heart Association—were significantly more likely to develop mental health problems, particularly clinical depression, even if they were not overweight.

Another disturbing finding showed that the observations about the participants' mental health persisted even in the years when they reported lower sugar intake—meaning the damage from excessive sugar consumption was prolonged.

Interestingly, there was no equally clear link found between sugar intake in women and the risk of depression or anxiety.

Why might excessive sugar consumption lead to the development of mental health issues? The leading scientific theory suggests that sweet food is quickly broken down by the body, causing blood sugar levels to rise immediately—and then drop. This drop puts the body into a stress state, which it responds to by releasing hormones like cortisol and adrenaline, which over time lead to the development of depression or anxiety.