A six-year follow up of over 12,000 men and women showed that those who regularly consume trans-fats (fats present in artificial form in industrially-produced pastries and fast food) are 48 percent more likely to develop depression in the long run.

This comes while these participants were just eating 1.5 grams of trans-fats from natural sources such as cheese and whole-fat milk per day, according to the online journal PLoS ONE.

Those who were used to consume more amounts of trans-fats, on the contrary, were also at a greater risk of developing depression besides other health hazards caused by eating fatty food, wrote Almudena Sanchez-Villegas of the University of Las Palmas de Gran Canaria, Spain.

Researchers also found that men and women who eat healthier fats such as olive oil were at a lower depression risk. Eating more than 20 grams of olive oil per day, similarly, reduced the risk of developing depression by 30 percent.

While referring to the growing number of depressed individuals, which already stand at 150 million worldwide, researchers added "on this basis we derive the importance of taking this effect into account in countries like the US, where the percentage of energy derived from these fats is around 2.5 percent."

They also linked the dramatic rise in the prevalence of depression "to radical changes in the sources of fats consumed in Western diets, where we have substituted certain types of beneficial fats -- polyunsaturated and monounsaturated in nuts, vegetable oils and fish -- for the saturated and trans-fats found in meats, butter and other products such as mass-produced pastries and fast food."

Scientists believe too much consumption of trans-fats contributes to inflammatory changes as well as atherosclerosis (plaque build-up in the arteries and brain), boosting the risk of heart disease and mood problems.