A new study has found that eating small amounts of dark chocolate, which is high in an antioxidant called polyphenol, can increase feelings of calmness and contentedness.

While eating too much chocolate is obviously still bad for you - no matter how high it is in antioxidants - the research is good news for all of us who just indulged in lots of dark chocolate over the long weekend. Unfortunately, the mental health benefits didn't hold for those who ate chocolate with little or no polyphenol, such as white chocolate.

"Anecdotally, chocolate is often linked to mood enhancement," said lead author of the study, Matthew Pase from Swinburne University of Technology in Australia. "This clinical trial was perhaps one of the first to scientifically demonstrate the positive effects of cocoa polyphenols on mood."

Pase and his team were looking into the effect of polyphenols on both mood and cognitive function. While there was no increase in cognitive function after the participants enjoyed chocolate for 30 days straight, the researchers did see an improvement in mood.

The research was conducted with 72 healthy men and woman aged between 40 and 65. The participants were given a dark chocolate mix to drink for 30 days with 500 mg, 250 mg, or 0 mg of cocoa polyphenols. Those enjoying 500 mg of polyphenols a day reported an increase in calmness and contentedness throughout the study period.

There are some limitations to the research - firstly, participants had to rate their own mood on 16 different scales to measure how they were feeling before the experiment, and then again after the 30 days of chocolate-eating. Self-reporting isn't the most reliable measure of mood, seeing as so many other factors can be involved, but there aren't many more reliable ways of measuring how content, calm, or happy someone is without asking them.  

It's also important to note that the study didn't find a causal link between the polyphenols and improved mood, so we can't definitively say that the dark chocolate was the cause of the better mood, or point to some kind of biological process that might have been involved. Maybe the participants were simply happier because they were consuming something they enjoyed.

We should also keep in mind that most research related to chocolate's health benefits have been shown to be overstated, and eating too much chocolate is still going to make you put on weight. But this study builds on previous evidence that dark chocolate could be good for you in small doses – other studies have found it can lower your risk of Alzheimer's and benefits platelet and vascular function.

More research is now needed to figure out whether polyphenols are the cause of this increased calmness and contentedness, and if so, whether they can be used to help those with anxiety or other mood disorders. Either way, we're just happy to have another reason to enjoy chocolate.

This research was published in the Journal of Psychopharmacology.

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