Chocolate: Pros and cons of this sweet treat

Is chocolate really good for the heart and brain, or is it just wishful thinking?

With Valentine's Day right around the corner, it's only a matter of time before the media starts salivating over the latest research touting the health benefits of chocolate. According to the headlines, chocolate is "good for you," "heart-healthy," and able to "sharpen seniors' brains." But does this indulgent treat live up to its hype?

The answer is yes—and no.

"The media snatch up a cocoa story and say, 'Eating chocolate is good for you, go out and eat chocolate bars.' That's not it," says Dr. Eric Ding, a scientist in the Department of Nutrition of Harvard School of Public Health.

The reality is that ingredients in cocoa can be healthy, but the high-calorie chocolate bars that contain it aren't necessarily good for you. Cocoa comes from roasted cacao seeds. It's high in plant compounds called cocoa flavonoids, which have been shown in studies to have beneficial effects on heart disease risks, as well as on blood flow to the brain. Chocolate is the candy that's made by adding sugar, milk, and other ingredients to cocoa powder. Those ingredients also add fat and sugar, which counteract some of cocoa's health benefits.

Cocoa and heart health

The flavonoids in cocoa—specifically catechin, epicatechin, and procyanidins—are thought to help the cardiovascular system by lowering cholesterol, reducing inflammation, and preventing blood clots. When Dr. Ding and his colleagues analyzed the results of 24 studies on the effects of cocoa flavonoids on heart risks, they found that flavonoids reduced blood pressure and unhealthy LDL cholesterol, increased healthy HDL cholesterol, improved blood flow, and lowered insulin resistance (a condition in which the body doesn't use insulin effectively, which is associated with type 2 diabetes and heart disease).

So far, researchers have only confirmed cocoa's short-term benefits on heart risks—not the outcomes of lowering those risks. In other words, cocoa flavonoids may counteract the high blood pressure, high cholesterol, and other factors that contribute to a heart attack, but whether they actually prevent one from happening isn't yet known. "In terms of actual direct heart attack prevention, the jury's still out," Dr. Ding says.

Cocoa on the brain

Scientists are also discovering that cocoa may be healthy for the brain. Another team of researchers at Harvard Medical School found that older adults who drank two cups of cocoa a day for 30 days had improved blood flow to parts of their brain needed for memory and thinking.

Another study, this one published in the journal Hypertension in 2012, offers even more direct evidence of cocoa flavonoids' effects on the brain. Researchers in Italy found that older adults with mild cognitive impairment (mild problems with memory and thinking skills that increase the risk for dementia) who drank high-flavonoid cocoa performed better on tests of mental function and speaking ability than those who drank low-flavonoid cocoa. These studies don't prove that cocoa can prevent dementia or other kinds of mental decline, but it does appear to play some brain-protective role.

Best cocoa sources

The average dose of flavonoids in the studies Dr. Ding reviewed was 400 milligrams a day. "The problem is, that's about the equivalent of eight bars of dark chocolate or 30 bars of milk chocolate," he says. "When you eat these actual chocolate bars, all the calories and sugar come with them."

To get the health advantages of cocoa flavonoids without the fat and calories, you can buy a more concentrated cocoa product. Some cocoa supplements on the market contain up to 250 milligrams of cocoa flavonoids per serving.

If you do want to indulge in a small piece of chocolate each day, make it dark. The higher the cocoa content of the bar, the better it is for your health (look for bars with 70% cocoa or more). Although a couple of chocolate squares may not do wonders for your heart and brain, they will please your taste buds without adding too many inches to your waist.