Ultra-Processed Foods Associated with Increased Risk for Depression

The Nurses’ Health Study II found that depressed women were significantly more likely to take in ultra-processed foods and fluids, particularly those flavored with artificial sweeteners (JAMA Netw Open, 2023;6(9):e2334770). In this study of 31,712 women between the ages 42 to 62, 4840 cases of depression were found, including 2122 cases of severe depression. The depressed women were also more likely to be fatter, more likely to smoke, more likely to suffer from diabetes, high blood pressure and high cholesterol, and less likely to exercise regularly. Those who reduced their intake of ultra-processed foods by at least three servings per day were at lower risk of depression, compared to those who did not reduce their intake over the next four years of follow up.

How Could Ultra-Processed Foods Increase Risk for Depression?
Depression has been associated with faulty communication between nerves in the brain (Pharmacol Ther, 2021;224:107821), and additives such as artificial sweeteners may decrease communication between brain nerves (Nat Neurosci, 2022;25(2):191-200). Other studies have also associated ultra-processed foods with depression but with no specific cause-and-effect (BMC Med, 2019;17(1):78; Front Nutr, 2020;7:600449; the SUN Project, 2020;59(3):1093-1103).

What Are Ultra-Processed Foods?
Ultra-processed foods are foods that have been made by removing nutrients such as fiber, vitamins, minerals or antioxidants and adding dyes, preservatives, antioxidants, anticaking agents, flavor enhancers, sugars, fats, salt and other ingredients. Ultra-processed foods include soft drinks, fruit drinks, most dry breakfast cereals, frozen pizzas, frozen meals and entrees, breads, cakes, pies, cookies, snack bars including power bars, diet bars and energy bars, candy, crackers, salty snack foods such as potato chips, corn chips and pretzels, processed meats including those made from poultry or seafood, instant soups and noodle bowls, salad dressings and many others. In North America, almost 60 percent of calories and more than 90 percent of the sugar are consumed in “ultra-processed foods” (BMJ Open, March 9, 2016;6(3)).

My Recommendations
Nobody really knows what causes depression, but several recent studies show that an unhealthful diet may be a factor. I believe that most people should base their diets on fresh foods such as fruits, vegetables, whole (unground) grains, beans, seeds and nuts, while decreasing intake of processed foods that come in packages such as cartons, bottles and cans.