A number of studies show the benefits of dark chocolate.

Does that make dark chocolate sound like a superfood?

Maybe so--especially when you factor in the effect eating dark chocolate can have on how happy you feel.

Recent research from University College London studied over 13,000 people and found that individuals who reported eating any dark chocolate in two 24-hour periods were 70 percent less likely to report clinically-relevant depressive symptoms than those who ate no chocolate at all.

Or in non-research-speak, eating dark chocolate can make you feel happier.

How? Dark chocolate contains psychoactive ingredients that produce feel-good results; one is phenylethylamine, a neuromodulator that helps regulate mood. Plus, dark chocolate contains a higher concentration of antioxidants that reduce inflammation, a condition linked to the onset of depression.

But before you reach for a candy bar, keep in mind there's a catch: All participants needed was half an ounce of chocolate per day.

And there's another catch: If you're watching your weight, even a small amount of chocolate has a calorie impact.

A half-ounce of dark chocolate typically contains between 70 and 80 calories, depending on the percentage of cacao solids, the paste that results from fermenting, roasting, and crushing cocoa beans. The cacao then gets mixed with other ingredients like milk and sugar to produce a wide range of chocolates.

While "dark chocolate" can contain as little as 45 to 50 percent cacao solids, research shows the greatest benefits come from dark chocolates containing at least 60 percent cacao solids.

And there's one more catch, but this time a good one. Since some dark chocolates contain as much as 85 percent cacao solids, you might be tempted to think venturing way over into the dark side will make you even happier.

Yet the evidence suggests mood improvements only occur if you enjoy the chocolate you eat, suggesting the experience of eating the chocolate is a factor as well.

Sure, the chemical ingredients can make an impact. But so can the taste.

All of which means the relationship between dark chocolate and mood may be more correlated than causal. As the researchers say:

This study provides some evidence that consumption of chocolate, particularly dark chocolate, may be associated with reduced odds of clinically relevant depressive symptoms. However, further research is required to clarify the direction of causation--it could be the case that depression causes people to lose their interest in eating chocolate, or there could be other factors that make people both less likely to eat dark chocolate and to be depressed.

But then again, past studies found that consuming chocolate may help improve your mood and make you feel calmer and more content, partly because dark chocolate stimulates the production of endorphins, the chemicals in the brain that create feelings of pleasure. And dark chocolate also contains serotonin, an antidepressant that can elevate mood.

Sounds pretty causal to me.

So if you enjoy chocolate, don't see a half-ounce as a diet killer. Even if you think it is, there's a simple solution: Eat your half-ounce, then take a 15-minute walk, preferably with a loved one or friend.

You'll burn off the calories while strengthening a relationship...and double-dip on chocolate's emotional benefits and the impact of walking on mood and cognitive ability.

Win-win-win-win.

Give it a try. (I am, especially since I love chocolate. That, to me, is an immediate "win.")

After all, if you find that eating a half-ounce of dark chocolate a day makes you happier and less likely to feel depressed...who cares how it works?