Researchers in Spain followed 12,059 people over six years, analyzing their diets, lifestyles and medical problems. The people who ate the most trans fats, which are commonly found in pastries and fast food, had a 48% increased risk of depression compared with people who did not eat trans fats. Individuals who ate a lot of polyunsaturated fats—a healthier type of fat that is found in olive oil, for example—had a lower risk of depression. The study was conducted on a population of people that, traditionally, does not consume a diet that is high in trans fats. Nevertheless, the connection between a higher trans-fat intake and depression was still noticeable.