There are weeks when I become so busy that prepackaged processed foods work their way into my daily diet. At the end of these weeks, I feel guilty, somewhat lethargic, and in need of a big salad and a long session at the gym. Now, according to a study conducted at University College London, there is evidence suggesting processed foods are not only bad for your physical health, but they also increase risk of depression.

The study indicates middle-aged people who eat processed foods such as fried food, processed meat and refined grains are more likely to suffer depression than those who eat a diet of whole fruits, vegetables and fish. Many processed foods pose health risks due to additives and processing methods that change the make-up of the food. For instance, trans fats, which are linked to heart disease, can be found in many processed foods. Other additives such as high fructose corn syrup and sodium nitrite are thought to cause health problems such as diabetes and gastric cancer.

Researchers at University College London found that people who ate less processed food had a 26% lower risk of depression five years later, where as people with a diet high in processed food had a 58% higher risk of depression. Researchers acknowledge that more studies are needed to rule out factors not considered in the study, and to explore why certain foods may guard against depression, while others increase risk of depression.

To avoid processed food, buy whole vegetables, fruit, and lean meats. Be sure to check labels. If a jar of spaghetti sauce or salsa says it contains high fructose corn syrup, buy a different brand or make your own. If you’re too busy to cook every night, make extra when you do have time and put it in the freezer. For a quick snack, buy pre-cut vegetables or unsalted nuts.