Chocolate is good for you...
Eating dark chocolate helps restore flexibility to arteries and prevents white blood cells from sticking to the walls of blood vessels. Those two factors play key roles in the prevention of atherosclerosis—a buildup of plaque that limits the flow of oxygen-rich blood.
Middle-aged, overweight men participated in an eight-week study. They ate 70 grams of chocolate per day (about 2.5 ounces). Some of the men ate regular dark chocolate and some received a special chocolate with a higher level of flavonols. Both chocolates had similar amounts of cocoa, and both produced the same positive results.
...but it isn’t good for dogs
Chocolate can cause life-threatening health problems in dogs, so take care to keep it out of reach and off countertops.
“Dogs have no off button,” Tina Wismer, DVM, told the New York Times. “If you or I ate 10 percent of our body weight in chocolate, we’d have the same problems,” which can include vomiting, diarrhea, agitation, elevated heart rates, or seizures. “A 10-pound dog can easily eat a pound of chocolate,” said Dr. Wismer, who is the medical director of the ASPCA’s Animal Poison Control Center.
Dark chocolate is more toxic to dogs than milk chocolate. Dogs will show signs of poisoning 6 to 12 hours after ingestion of a toxic dose. Contact your veterinarian or an emergency clinic if symptoms arise.
“Why Dark Chocolate Is Good for Your Heart,” Federation of American Societies for Experimental Biology, 2/27/14
“Ask Well: The Problem with Dogs and Chocolate” by Catherine Saint Louis, New York Times, 2/14/14