A new study published in The British Journal of Psychiatry makes a strong case that processed junk food can trigger or contribute to depression, while eating whole and healthy food seems protective.
British and French epidemiologists analyzed food and mood data from 3,486 men and women (average age 55) in the Whitehall II study on London-based office staff. Each participant answered a food frequency questionnaire in which they were asked how often they had eaten a designated portion size of a food during the previous year (set responses ranged from "never" to "six or more times per day").
That data was then converted to a daily intake and two dietary patterns were identified: the "whole food pattern" (defined by a high daily intake of vegetables, fruits, and fish) and the "processed food pattern" (characterized by high consumption of sweetened desserts, chocolates, fried food, processed meat, pies, refined grains, high-fat dairy products, and condiments). Five years later, all the participants answered a short questionnaire designed to measure symptoms of depression in the general population.
After adjusting for variables such as age and sex, the scientists found that high consumption of processed food was associated with increased likelihood of depression, whereas those who had the highest consumption of whole foods were least likely to be depressed, and even less likely than those in the whole food pattern who ate fewer whole foods.
What it means
Junk food may taste good, but along with the detrimental effects of all that sugar and fat on your body, eating it makes you feel low as well. The researchers are pretty confident that they've uncovered a true cause-and-effect relationship.
"Our finding shows a strong association between diet and depressive symptoms after controlling for a large range of socio-demographic factors, and for health behaviors such as smoking, physical activity, and health status," notes lead study author Tasnime Akbaraly, PhD, an epidemiologist with the National Institute of Health and Medical Research in Montpellier, France. While it's possible that a healthy diet is a marker of some other factor that protects against depression, "the effect of diet on depressive symptoms didn't go down after we adjusted for other indicators of a healthy lifestyle, such as smoking, physical activity, and body mass, Akbaraly says. "What we found isn't a spurious association."
Here's how to eat for optimal mental, as well as physical, health:
- Pay attention to your patterns. In this study, those who ate the most processed foods every day were most likely to suffer from depression. "I suggest using our findings as your guide," says Akbaraly. "That is, reducing consumption of processed meat, fried food, refined grains, refined sugar, and high-fat dairy products, and making sure to eat fresh fruit and veggies every day.
- Eat breakfast. People who eat breakfast tend to have higher total calorie intakes throughout the day, but they also get significantly more fiber, calcium, and other micronutrients than skippers do. Breakfast eaters also tended to consume less soda and french fries (processed food pattern) and more fruits, vegetables, and milk (whole food pattern).
- Snack on whole foods. Substitute at least one processed snack a day for a whole foods version — swapping out, say, chips and choosing raw carrots, almonds, or cheese on a whole wheat cracker instead.
- Analyze food labels. A quick rule of thumb: The shorter the ingredients list, the healthier (read: less processed) the food. Stick with simple. Your psyche will thank you. Studies show people who read food labels first also consume fewer calories on average.
- Watch your salt. According to United States Dietary Association reports, most of the salt in the American diet comes from packaged and processed foods. Naturally occurring salt accounts for only 12 percent of total intake, while most of the rest is added by food manufacturers.
- Set the table. Children in families with more structured, sit-down mealtimes tend to exhibit healthier eating habits. No doubt, the same is true for adults, too. Aim to make a healthful, sit-down dinner for the family at least once a week. Maybe it'll become a habit — and your consumption of fast-food dinners will become history.
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