Many studies show that poor diet plays a role in depression and some inflammatory disorders, including heart disease. An imbalance of certain dietary fats may be to blame, according to a study published April 23 in Psychosomatic Medicine.
Omega-3 polyunsaturated fatty acids—plentiful in fish, nuts, and vegetables—are thought to protect against heart disease, Alzheimer’s disease, and depression. But another type of fatty acid, omega-6, may contribute to both depression and inflammation.
Omega-6s are found in processed vegetable oils. The typical American diet contains about 20 times as many omega-6s as the more beneficial omega 3s. Some studies suggest a link between this ratio and depression.
Janice Kiecolt-Glaser of Ohio State University and colleagues examined 43 men and women, ages 40 to 86. About half were caring for spouses with Alzheimer’s disease, making the group more prone to stress and depression than a cross-section of people.
Those with a higher ratio of the “bad” omega-6 fatty acids, combined with depressive symptoms, showed drastically higher levels of inflammatory cytokines. Because inflammation plays a role in diseases from arthritis to many cancers, the finding shows the importance of a healthy diet, for those with and without depression.
It also lets omega-3s share the spotlight. “Omega-3s are beneficial, but they’re not the whole story,” Kiecolt-Glaser notes. “Another good choice is to reduce levels of omega-6s by eating more fruits and vegetables and fewer processed foods that contain vegetable oils.”