They found that the more women consumed added sugars and refined grains and the higher their score on the glycemic index (GI) — a measure of the rate carbohydrates are broken down and absorbed by the body — the more they were at risk of new-onset depression.
Those who had a different sort of diet — one with more dietary fiber, whole grains, vegetables and non-juice fruits — had a decreased risk.
"This suggests that dietary interventions could serve as treatments and preventive measures for depression," wrote James Gangswisch, an assistant professor of psychiatry at Columbia University Medical Center, and his co-authors.
The researchers explained that refined foods trigger a hormonal response in the body to reduce blood sugar levels. That is believed to lead to the "sugar high" and subsequent "crash" some people say they feel after eating such foods. This can lead to mood changes, fatigue and other symptoms of depression.