Researchers followed 43,000 women who started off without depression over a period of 12 years and found that those with diets linked to inflammation were 29 to 41 percent more likely to suffer some form of depression by the end of the study.
The specific diet triggers were soft drinks, fatty red meat and refined grains such as pasta, white bread and chips.
Dr. Michael Lucas, a Harvard researcher who co-authored the study, said the causes of mood disorders are hard to pinpoint. He said it's not clear how inflammation affects mental health, but there does appear to be a link.
Food choices that help keep inflammation down include olive oil, coffee, wine, carrots, sweet potatoes and leafy greens, Lucas said.