I already mention on the health supplements page that there are definitely supplements to invest in before healthy chocolate. But since many of us want to eat chocolate anyway, it's worthwhile to find the type that will add to our health rather than take from it.
Likewise, if you really wanted the optimal health benefits of "chocolate," you'd go right back to the source -- raw cacao. No, this isn't chocolate. But all chocolate is made from cacao. And this is what gives chocolate its healthy qualities. (Cacao nibs are shelled cacao beans, and are used to produced cocoa liquor.)
Cacao is loaded with magnesium -- in fact, it may be the richest food source of magnesium available. This is great for muscles and nerves, the heart, the immune system, the bones, and much more. It helps to regulate blood sugar and blood pressure, and is otherwise involved in hundreds of biological functions. It is also the #1 deficiency among macro minerals in the average American diet. This is one reason why cacao can be an important nutritional supplement in our culture.
Cacao also contain a good deal of sulfur, as well as calcium, zinc, iron, copper, and potassium. And famously, it's a great source of theobromine, which is the active ingredient in cacao and in chocolate and gives chocolate its stimulant quality. (Contrary to popular belief, there may not be caffeine in cacao. However, this is still under debate.)
Perhaps the most marketed quality of cacao is its antioxidant capacity, with more flavanoids than red wine, green tea, or blueberries. This is what gives chocolate -- especially dark chocolate -- its high ORAC score. (ORAC stands for Oxygen Radical Absorbance Capacity. Free radicals cause all sorts of damage to the body. Antioxidants are able to "absorb" or eliminate free radicals, so getting plenty of them is important. More about this on the ORAC page.)
Best of all, compared to many of the nutritional supplements available today, cacao nibs are not expensive. You can get them for about $1 per ounce. By comparison, raw chocolate typically costs about $3 to $5 per ounce.
Having said that, most cacao is bitter (unless you get the best beans), and a lot of people would have a hard time eating it directly. So again, most of us will turn to chocolate, and the goal is to get the healthiest kind.
All dark chocolate will provide health benefits along the same lines as cacao (from antioxidants, magnesium, and other nutrients), but not to the same degree -- for instance, some chocolates use more cacao, some are closer to the natural state, etc. At the same time, many companies will add other ingredients to their dark chocolate to provide additional health benefits. More on that within my reviews of specific products.
Now before we're finished with the topic of cacao, it's important to understand the types of beans available. Much like coffee or wine, there are big distinctions between basic cacao and premium.