Diet and Depression continued...
The biological changes that occur with high consumption of ''bad'' fats may explain both the heart disease and depression link, the researchers say.
The ill effects of bad fats on heart disease are believed to be due to increases in LDL “bad” cholesterol and reductions in HDL “good” cholesterol. There are also inflammatory changes, and these changes have also been linked with depression, the researchers say.
Inflammation may interfere with the brain's neurotransmitters, such as serotonin, Sanchez-Villegas says, and a lack of serotonin adversely affects mood.
The new research adds to a growing body of evidence about the importance of the type of fat eaten, says Jian Zhang, MD, DrPH, a researcher at Georgia Southern University in Statesboro, who has also studied the link between dietary fat and depression and published a study.
Increasingly, Zhang says, studies are ''suggesting physical health and mental well-being are sharing nutritional factors related to subtypes of fatty acids."
Studies have found some conflicting results. In Zhang's research, the epidemiologist found gender differences regarding fat intake and mood. Zhang found that an increased intake of oleic fatty acids, a monounsaturated fatty acid, was linked with a reduced risk of depressed mood among women, while an increase in linoleic fatty acids, an unsaturated fatty acid, was linked with an increased risk of depressed mood among men.
Despite the conflicting results, Zhang says, ''almost all evidence, anecdotal or scientific, consistently pointed out olive oil is good."
Sanchez-Villegas says the study looked at university graduates in a Mediterranean setting, so the finding of high olive oil intake is not surprising.
Their consumption of trans fats was fairly low overall. The intake in the highest of the five groups was 1.5 grams a day, and that amount is low compared to other populations, including the U.S., Sanchez-Villegas says.
For that reason, the suggestion to watch your intake of trans fat might be especially important, Sanchez-Villegas says, in the U.S. and other locations where the population tends to eat higher amounts.