Hershey Kisses for Your Heart

Dark chocolate may help lower blood pressure and bad cholesterol and cardiovascular risk

/ Author:  / Reviewed by: Joseph V. Madia, MD

(RxWiki News) True or false: Chocolate is good for you. Yes, it's a trick question, so a couple of nutrition researchers set out to find out what kind of benefits chocolate does offer.

One of the ingredients in chocolate thought to offer some health benefits are flavanols, which are antioxidants that appear to help reduce inflammation.

Although various studies have shown a link between how many flavanols a person consumes and their reduced risk of cardiovascular disease, this association does not mean eating chocolate will prevent a heart attack.

"Consider eating a daily piece of dark chocolate in moderation."

But Christina Orsa, a masters candidate in nutrition at San Diego State University, and her colleagues wanted to find out whether dark chocolate could help protect against cardiovascular disease by lowering blood pressure and blood flow and by improving a person's blood lipid levels.

They conducted a very small study for a short period of time, so the study duration and participant number limit the value of the study. The study also has only been presented at a conference and has not yet been accepted to a peer-reviewed journal.

The researchers split 31 healthy participants into three groups. All the participants had normal blood pressure (less than 120/80) and were of a normal weight (18.5-25 body mass index).

One group had a daily serving (50 grams) of dark chocolate that contained 70 percent cocoa.

Another group had the same type of dark chocolate, but it had been overheated and therefore "bloomed" (where the surface has that white moldy-like texture). This type of chocolate was included to see if the blooming had any effect on the flavanols in dark chocolate.

The third group had a 50 gram daily serving of white chocolate, which contains no cocoa. All three groups ate their chocolate for 15 days. The researchers asked the participants to keep their daily diet the same during the two weeks of the study.

The researchers took readings on all participants' blood pressure, blood flow in the forearm skin, lipid profiles and blood glucose levels at the start and completion of the study.

The dark chocolate eaters (of both forms) had lower blood glucose and lower LDL "bad" cholesterol levels, along with higher levels of HDL, or "good" cholesterol, compared to the white chocolate munchers.

Those eating the normal dark chocolate had the largest decrease in blood glucose. The average reading for that group was 88 mg/dl on the first day of the study, which had dropped to an average 82 mg/dl on the 15th day of the study.

Those who ate the bloomed dark chocolate had an average glucose level of 83 mg/dl on the first day of the study, which dropped only slightly to 80 mg/dl on the last day.

Orsa told dailyRx that the study was too short to determine what longer-term effects of the dark chocolate might be on the participants' glucose levels.

"We don't know whether it would continue decreasing or stay lower or return to its previous levels," Orsa said. She said the slight increase that occurred in blood glucose levels of the white chocolate eaters - from 86 mg/dl to 88 mg/dl - may have been because they were consuming more fat and sugar on top of their regular diet.

In fact, Orsa said they had concluded that a person might be able to reduce some of their risk of cardiovascular disease by regularly eating dark chocolate, but it would be important to eat it only in moderation.

The data they collected on the participants' calorie intake showed a great caloric intake at the end of the study than the beginning, most likely because the participants were eating chocolate in addition to their normal diets.

Because of the high fat and calorie content in chocolate, Orsa said, a person who consumes it regularly would need to remove something else from their diet to ensure they are not eating too many calories.

The research team plans to conduct additional trials with more people eating chocolate for a longer period of time to learn more about its effects on cardiovascular risk.

The research was presented April 24 at the Experimental Biology 2012 meeting in San Diego. The study was funded internally by San Diego State University. Other than liking chocolate, the authors had no conflicts of interest.

Reviewed by: 
Review Date: 
April 25, 2012
Last Updated:
May 7, 2012