By Dr. ALETHEA TURNER, ABC News Medical Unit

You've heard of eating comfort food to make you feel better, but did you know eating fast food may be linked to clinical depression?

Researchers in Spain claim that depression is 51 percent more likely to occur in people who consume large amounts of fast food - like hamburgers, hot dogs and pizza - compared to those who don't.

"The more fast food you consume, the greater the risk of depression," Almudena Sanchez-Villegas, lead author of the study, said in a statement.

And don't forget about other junk food items, like doughnuts and croissants. According to the study, they are also linked to mood problems.

But experts suggest that it may not be the food that is causing the depression.

"Higher intake of fast food may very well increase risks of depression by causing poor health in general," said Dr. David  Katz, director of Yale University's Prevention Research Center in New Haven, Conn. "But depression may also increase fast food intake."

"We use the term 'comfort food' for a reason," he added. "It can help alleviate stress, anxiety, and depression. So it may be that people with depression are turning to [fast food] for relief."

Katz suggested that other factors may also be at play. Poverty, for example, is linked to both fast food intake and mental health problems.

Researchers also noted that subjects were less active and more likely to smoke and work greater than 45 hours per week.

"Let's be real and keep it in context here," said Keith Ayoob, a registered dietitian and associate professor at the Albert Einstein College of Medicine in New York. "This is reflective of a lifestyle with many unhealthy aspects.

"It does not mean that if you go eat a hamburger you are going to become depressed," Ayoob said. "I think this represents a reflection of depression, not the cause."