The health benefits are derived from the cocoa bean, or cocoa. Today's common chocolates are typically a mix of cocoa, sugar and milk with less than optimal amounts of cocoa for health benefits and far too much sugar. As sugar should definitely be avoided, if you plan on adding any type of chocolate to your diet (I have), cocoa or if you can't tolerate cocoa on its own, at a minimum dark chocolate with a minimal amount of sugar added should be selected.
Remember, not all dark chocolate is created equal - some have a lot more sugar than others - check the percentage of cocoa. There is dark chocolate available with 60% cocoa (which means 40% is sugar) as well as 95% cocoa (only 5% sugar), yet both are called dark chocolate.
Here is a link to an interesting, detailed article about the many health benefits of cocoa:http://www.medicinehunter.com/cocoa-health-miracle
I have read that in order to maximize the health benefits, you need to consume 3 1/2 to 7 ounces of pure cocoa daily (ouch, that is an awful lot and realistically may not be possible to do). And the only way to do this properly in reality is by consuming pure cocoa (100% cocoa, 0% sugar). I recently began making my own kefir (a fermented milk product loaded with probiotics) and mix 4 tablespoons of pure cocoa (about 1 1/4 ounces) with 1 cup of kefir and have this twice a day. For those of you with a sweet tooth, you likely will not enjoy this but the combination offers tremendous health benefits!
Here is a link to an article that outlines the many health benefits of kefir:http://authoritynutrition.com/9-health- ... -of-kefir/
Making kefir is easy. If you plan on adding kefir to your diet, do not buy kefir in the supermarket as it is loaded with sugar. It is really, really simple to make at home and it should be made ONLY with milk from grass fed cows which will not be readily available at your local supermarket. If you are fortunate enough to have a Whole Foods store in your neighborhood, milk from grass fed cows is readily available.