Among dark chocolate’s most researched benefit is its role in preventing heart disease. British researchers analyzed seven studies on chocolate and cardiovascular health involving more than 114,000 people in the United States, Germany, Japan, the Netherlands, and Sweden and found that people who ate more chocolate significantly reduced their risk for heart disease. Researchers concluded that people who ate the most chocolate weekly had a 37 percent lower risk of any heart disease than those who ate the least amounts of dark chocolate.

Along the way, the benefits of dark chocolate have pushed its popularity. You’ve probably seen dark chocolate listed among “must-eat healthy foods” in compilations written by various nutrition experts. Yet depending on how it’s made, dark chocolate also can be high in calories, fat, sugar, and preservatives. So, what’s the real deal? Is dark chocolate healthy?

Your dark chocolate of choice should also be made from cocoa butter, not palm and/or coconut oils. Also look out for any hydrogenated or partially hydrogenated oils in the ingredient list. Now that huge commercial chocolate makers are responding to the love of dark chocolate and making their own versions, you have to be careful. A label that reads “dark chocolate” doesn’t automatically make it a healthy choice. The healthiest or best dark chocolate is made from cacao or cocoa that’s organic, minimally processed and definitely not dutched.
Chocolate tastes sinfully sweet, but you may no longer need to feel guilty about indulging in an ounce or two a few times a week. A growing number of studies show that chocolate, especially antioxidant-rich dark chocolate, has health benefits that put it squarely on the latest list of superfoods. A key reason chocolate has so many health benefits is that it is rich in flavonoids, which are naturally occurring substances found in plants that can provide a serious boost in antioxidant action for you.
Elevated blood glucose harms blood vessels. Blood vessel damage is the major cause of the vascular complications of diabetes, leading to other problems, such as damage to blood vessels in the brain and eyes causing retinopathy. Studies of long-term diabetics show progressive brain damage leading to deficits in learning, memory, motor speed, and other cognitive functions.
Can't remember where you put your keys or why you walked into a particular room? Chocolate may help: Recent research suggests that antioxidants called flavanols found in cocoa can helpimprove function in the area of the brain responsible for this type of age-related memory loss. Participants in the study were placed on a special diet high in raw cocoa flavanols called epicatechin. At the end of the three-month period they scored significantly higher on memory tests than the control group. 

Promotes weight loss – Researchers from the University of Copenhagen found that dark chocolate is far more filling, offering more of a feeling of satiety than its lighter-colored sibling. That is, dark chocolate lessens cravings for sweet, salty, and fatty foods. So if indulging in a bit of healthy dark chocolate should not only make it easy for you to stick to the small portion recommended for optimal health, but it should make it easier for you to stick to your diet in general.
Herbert had softer stool for all the days of the challenge, and on seven out of the 14 days she went to the bathroom more than once. "This is not normal for me, but everything was 'smoother'. I started using Xylitol [a sweetener] towards the end, but it upset my stomach. This was a side-effect that made it more difficult to sustain the challenge."  
The samples were classified into 24 different categories covering products from the plant kingdom, products from the animal kingdom and mixed food products. Information about sample processing (raw, cooked, dried etc), if any, was included, along with all sample specifications, i.e. product name, brand name, where the product/sample was procured and country of origin. The product information in the database was collected from the packing of the product, from supplier or purchaser. When this information was not available or the samples were handpicked, only country of origin is presented. Each sample is assigned to only one category. The classification was done according to information from the supplier or purchaser, or according to common traditional use of the food. Some foods may therefore be categorized otherwise in other food cultures. For products in the categories "Herbal/traditional plant medicine" and "Vitamin and dietary Supplements" some products may rightfully be classified as both an herbal medicine and a supplement, but are still assigned to only one category. All berries, fruits, and vegetables were fresh samples unless otherwise noted in the database. The Antioxidant Food Table contains 3139 samples. About 1300 of these samples have been published before [16,17,28] but for comparison and completeness we have included them in the present publication. All individual samples previously published are identified by a comment in the Antioxidant Food Table. The categories and products in the database are presented in alphabetic order. Information about brand names and product trademarks does not imply endorsement by the authors, and are reported as descriptive information for research applications only. The Antioxidant Food Table will in the future be available online as a searchable database. In addition to the products mentioned in this paper, other foods will in the future be analyzed and incorporated into the online version, which will be posted on the University of Oslo's web site.