The Australian Bureau of Statistics estimates that 2.1 million Australians, or 9.3 per cent of our population, are suffering from some form of depression.
A growing body of research indicates that what we eat plays a role in determining our risk of depression. While there is good evidence connecting ultra-processed foods (UPF) — foods that are energy-dense, hyperpalatable and ready to eat (mostly anything in plastic packaging at your local supermarket) with various health issues, there is less data on their link to depression. Past studies have found it difficult to associate short-term diet data (over a week or month) with diagnoses of depression, or how these processed foods interact with other factors.
Now new research delves into the potential link between UPF, its components, and the onset of depression. This research used data on women involved in the Nurses Health Study, conducted in the United States between 2003 and 2017. Among other information, researchers collected diet data using food frequency questionnaires every four years (which get people to report what they eat and how often). These foods were then categorised according to their degree of processing. They also checked whether these women had depression, indicated by clinical diagnosis and antidepressant use. The study included almost 32,000 women with an average age of 52.
The researchers found those who ate ultra-processed foods more often had a higher BMI, higher rates of smoking, and were more likely to have hypertension and diabetes. And compared to those in the lowest fifth of ultra-processed food consumption, those in the highest fifth had a 49% increased risk in depression. That was even after adjusting for known confounding factors for depression – things like smoking, physical activity, age, income and marital status. Digging into the specific components of an ultra-processed food that may be harmful, they found that artificially sweetened drinks and artificial sweeteners more broadly were linked to greater risk of depression but weren’t able to identify particular other components of ultra-processed foods associated with depression.
While the exact mechanism by which UPF influence someone’s risk of depression is still unclear, recent findings suggest that artificial sweeteners might affect certain brain transmissions that could be linked to the development of mood disorders. As ever, Michael Pollan’s advice on foods is cogent: “Eat food. Not too much. Mostly plants.” He might even consider adding a fourth line – “Nothing in plastic!”
Consumption of Ultra-processed Food and Risk: JAMA Network