Study links ultra-processed foods to increased risk of depression

Consumption of ultra-processed foods appears to increase the risk of depression, warns a vast international study involving hundreds of Quebecers.

The association was particularly notable among young adults aged 18 to 34.

The association with depression persisted and even seemed to increase in women aged 35 and over. On the other hand, among adults aged 35 and over, and particularly women, a diet rich in fruit, vegetables, nuts, and fish was associated with a lower risk of depression.

“In our results, we can clearly see that the usual variables such as obesity, smoking, not having a job or being inactive are associated with the presence of higher depressive symptoms,” said Dr. Sylvain Iceta, head of the Quebec component of the study, who is a psychiatrist and researcher at the Research Centre of the Institut universitaire de cardiologie et de pneumologie de Québec-Université-Laval.

“But we’ve also just shown that diet itself will be associated with a higher risk. And in the various foods we have studied, ultra-processed foods, junk food, but also very prepared meals, will be associated with a higher risk in women.”

The international ALIMENTAL study was coordinated by a French doctor, Dr. Guillaume Fond. It was conducted online between 2021 and 2023 and involved more than 15,000 participants in nine countries, including 500 in Quebec.

More than a third of the 15,000 or so participants, who had no chronic illness or current psychotropic treatment, were nevertheless classified in the depression group.

“The idea was really to focus on a general population, on the average person, to see what might be happening in terms of the links between diet and depression,” explained Dr. Iceta.

The results highlight the importance of a personalised approach to public health. According to the press release, “individuals probably do not have the same level of risk or the same sensitivity to diet,” depending on their age and sex.

By identifying the groups most at risk, this study could help to develop more appropriate prevention programmes, it added.

“The data from the study do not allow us to determine with certainty why the risk of depression seems to increase over time, but there is probably some logic behind it,” said Dr. Iceta.

“It looks like there’s a cumulative risk,” he explained. “As if, as the years go by, this accumulation of bad food could increase the risk.”

The authors of the study also found that nutritional knowledge was associated with a reduced risk of depression – in other words, that people with better nutritional knowledge were less likely to have depressive symptoms.

“All of this is interesting,” said Dr. Iceta, because it “could be interesting avenues for intervention in the general population, to provide better information about these foods and to better educate the population from a nutritional point of view.”

“I think that the link between diet and mental health is too often neglected,” concluded the researcher. “It’s too simple to say that people are depressed because they’re obese, or that they’re obese because they’re depressed. We really need to take a closer look at what’s going on. And then we see that the quality of food ultimately counts for a lot when we’re talking about mental health.”

–This report by La Presse Canadienne was translated by CityNews