Study after study proves that dark chocolate – sweet, rich, and delicious – is good for more than curing a broken heart. The secret behind its powerful punch is cacao, also the source of the sweet's distinct taste. Packed with healthy chemicals like flavonoids and theobromine, this little bean is a disease-killing bullet.

Stick to healthy chocolate with at least 70 per cent cacao (or cocoa, which is cacao in its roasted, ground form). As long as the content is that high, says Mary Engler, Ph.D., a professor of physiological nursing at the University of California at San Francisco, you can reap the benefits from eating only small amounts. Because of its high fat and sugar content, limit yourself to 7 ounces, or about four dark chocolate bars, a week. Here are nine sweet health benefits of dark chocolate.

1. A healthier heart
The latest research backs up claims that chocolate has cardiovascular benefits: In a nine-year Swedish study of more than 31,000 women, those who ate one or two servings of dark chocolate each week cut their risk for heart failure by as much as a third.

Another long-term study in Germany found that about a square of dark chocolate a day lowered blood pressure and reduced risk of heart attack and stroke by 39 per cent. Most of the credit goes to flavonoids, antioxidant compounds that increase the flexibility of veins and arteries. But since those antioxidants come with a generous portion of sugar, milk, and butter, eating chocolate isn't an excuse to skip your workout. Chocolate and exercise actually work surprisingly well together. Another recent study in Australia showed that eating chocolate high in healthy antioxidants reduced the blood pressure-raising effects of exercise on overweight individuals. So go ahead and reward yourself. A chocolate bar has five times the flavonoids of an apple, after all.

2. Weight loss
If you are wondering how you can add dark chocolate to your diet plan without putting on pounds, the good news is that it is easier than you expect. Researchers from the University of Copenhagen found that dark chocolate is far more filling, offering more of a feeling of satiety than its lighter-coloured sibling. That is, dark chocolate lessens cravings for sweet, salty, and fatty foods.

3. Happier kids
Women who ate chocolate daily during their pregnancy reported that they were better able to handle stress than those who abstained. Also, a Finnish study found their babies were happier and smiled more.

4. Diabetes prevention
In an Italian study, participants who ate a candy bar's worth of dark chocolate once a day for 15 days saw their potential for insulin resistance drop by nearly half. "Flavonoids increase nitric oxide production," says lead researcher Claudio Ferri, M.D., a professor at the University of L'Aquila in Italy. "And that helps control insulin sensitivity."

5. Reduced stress
UC San Diego researchers recently confirmed: When times get tough, people tend to dip into the chocolate stash more often than they might otherwise. And as it turns out, that kind of emotional eating might not be such a bad thing. Swiss scientists found that when very anxious people ate an ounce and a half of dark chocolate every day for two weeks, their stress hormone levels were significantly reduced and the metabolic effects of stress were partially mitigated. After a breakup, break out a dark chocolate bar rather than a pint of ice cream.

6. Sun protection
London researchers recently tested chocolate flavanols' sun-protecting prowess. After three months of eating chocolate with high levels of flavanols, their study subjects' skin took twice as long to develop that reddening effect that indicates the beginning of a burn. Subjects who ate conventional low-flavanol chocolate didn't get the same sun protection.

7. Higher intelligence
Next time you are under pressure on a work project, don't feel so guilty about grabbing a dark chocolate bar from the vending machine. Not only will it help your body ward off the effects of stress, but it'll boost your brain power when you really need it. A University of Nottingham researcher found that drinking cocoa rich in flavanols boosts blood flow to key parts of the brain for 2 to 3 hours, which could improve performance and alertness in the short term.

Other researchers from Oxford University and Norway looked at chocolate's long-term effects on the brain by studying the diets of more than 2,000 people over 70 years of age. They found that those who consumed flavanol-rich chocolate, wine, or tea scored significantly higher on cognitive tests than those who didn't.

8. Cough Relief
One study found that chocolate quieted coughs almost as well as codeine, thanks to the theobromine it contains. This chemical, responsible for chocolate's feel-good effect, may suppress activity in a part of the brain called the vagus nerve.

Maria Belvisi, a professor of respiratory pharmacology at the National Heart and Lung Institute in London, says, "It had none of the negative side effects." Codeine makes most people feel sleepy and dull – and doesn't taste anything like fine chocolate.

9. Diarrhoea relief
Both South American and European cultures have a history that dates back to the 16th century of treating diarrhea with cocoa. Modern-day science has shown they were onto something. Scientists at the Children's Hospital Oakland Research Institute found that cocoa flavonoids bind to a protein that regulates fluid secretion in the small intestine, potentially stopping the trots in their tracks.