At first glance, I am always quick to assume the worst in any candy or sweet, although in this case, chocolate has been shown in studies to promote stress relief. An experiment provided by the National Library of Medicine showed, "Mean stress scores decreased, on average, by approximately 2 and 3 points in DC and MC groups, respectively, at a 95% Confidence Interval."(Sunni, 2014). This represents a dramatic decrease in stress levels just from a simple sweet treat. The reasoning behind the sweets' power lies in the satisfaction. When indulging in a treat, your brain releases serotonin, the reaction of something that makes you feel much happier. Within this process, stress chemicals like cortisol are countered by the opposing feelings. Creating a stress-relieving effect within the participants. The study does show another major fact, including "The difference was more evident and statistically significant in female students as compared to the males."(Sunni, 2014) This does not mean that the males were not affected; The impact was just not as significant in the experiment on the males as compared to the females. The only thing I would change about this claim would be the fact that they don't specify the amount. If eaten in a moderate portion, I believe it is beneficial, but in the other case, if it is over done would it not hurt the consumer more than improve their mental wellbeing? Similar to the feeling you get when you eat too much and don't feel good after, would be a close example.
https://pmc.ncbi.nlm.nih.gov/articles/PMC4350893/
Al Sunni, Ahmed, and Rabia Latif. “Effects of chocolate intake on Perceived Stress: a Controlled Clinical Study.” International journal of health sciences vol. 8,4 (2014): 393-401.