The day her study on the cardiovascular benefits of dark chocolate was published in the Journal of the American College of Nutrition, Mary B. Fngler, RN, PhD, MS, a professor at the University of California, San Francisco School of Nursing, got a call from the university press office, asking if she could do an interview for the CBS Evening News.
The television crew hung black drapes in her office to block the glare and asked if she had a model of a heart to use as a prop while they filmed. They shined a red light on the heart. They had her look at a university press person while she talked on a speaker-phone to the program director, who called from New York. They instructed her not to look at the phone or camera. The setup and taping took three hours. “They only showed 10 seconds,” Engler says, laughing. It was her induction into a place few nurse researchers ever bask — the national media spotlight.
Mary Engler and her identical twin sister, Marguerite M. Engler, RN, PhD, MS, FAHA, have been researching the relationship between nutrition and heart health since the early 1980s. Marguerite is also a professor at the UCSF School of Nursing and a coauthor of the chocolate study. The Englers’ previous research has included studies on the cardiovascular benefits of omega-3 fatty acids found in fish oils, and early nutritional interventions for children and adolescents who are at increased risk for coronary artery disease.
But the work that the media and a sweets-loving public have taken straight to heart is the Englers’ study showing a connection between dark chocolate rich in flavon-oids — antioxidant plant compounds — and improved blood flow. The study, released last June,2004, has resulted in media stories around the world and national television coverage. Fish oils, the Englers say, never generated such a response. They have received e-mails, phone calls, and requests for interviews for TV, radio, newspapers, journals, magazines, and websites. The chocolate study has been picked up by national and international medical and health science publications and has received more press coverage than any other research done by the school of nursing this year, according to the university press office and Kathleen Dracup, RN, DNSc, dean of the school of nursing. “I was overwhelmed,” says Mary. “It was nonstop.” She and Marguerite are sitting in a conference room down the hail from their offices in the school of nursing. They seem amazed at the response the chocolate study is still receiving. People continue to call with chocolate questions. What is the best dark chocolate? Can I eat chocolate every day? A company in Brazil was interested in making chocolate with a higher cocoa content because of its possible health benefits. A food magazine editor asked if a chocolate dessert would be a healthy end to a holiday meal. Cardiovascular colleagues in Italy have expressed interest in future research collaborations. Mary and Marguerite suspect the chocolate study received so much attention because so much of nutrition news tells people something is bad for them. “It was nice for people to get some good news,” Mary says. “A lot of people wrote, ‘Thank you for doing this study, it’s so important,”’ says Marguerite.
The Englers are striking women, tall and blonde with soft, high voices and elegant, expressive hands. They often finish each other’s thoughts and sometimes each other’s sentences. They laugh a lot and exchange bemused glances when they talk about how colleagues and students have sometimes mistaken one of them for the other. Even Dracup says she initially had trouble telling them apart. The closeness between them has served them well in the demanding field of research. Dracuo says. Research partners must rely on each other to meet deadlines, do the work properly, and carefully, and follow through on a project. “You have to create a relationship built on trust,” Dracup says. “I think they both brought that to their professional relationship.” ~~Who could you trust more than your sister?” asks Mary. “And I know Marguerite’s exceptional background and training.”
The Englers’ career paths are almost as identical as they are. They went to nursing school together in Virginia and received advanced degrees in biology and physiology from American University and Georgetown University in Washington, D.C. They both did doctoral research training at the National Institutes of Health in Bethesda, Md., and worked on critical care and cardiovascular surgery units there. They came to UCSF in 1988 to teach physiology and help establish a cardiovascular graduate nursing program at the School of Nursing. At UCSF they have separated a bit, following new interests, Dracup says. Mary has become interested in genetics and is the director of the nursing school’s new genetics program, and Marguerite has focused on clinical trials, she says. But their offices are next-door and they share a house. “They’re still very knowledgeable about each other’s research,” Dracup says.
While caring for patients before and after open-heart surgery on the cardiovascular unit at the NIH, the Englers talked to them about their diets and lifestyle habits. ‘After seeing how invasive heart surgery was, we thought, ‘There has to be a better way,”’ Mary says. Prevention of heart disease through diet and exercise seemed like a logical answer. This led to their interest in nutrition and specifically the effects of omega-3 fatty acids on vascular health. They spent more than 10 years doing laboratory research. Among other important discoveries, they found that the major omega-3 fatty acid, docosahexaenoic acid (DHA), could cause significant dilation in certain arteries. They designed a study in the late 1 980s that involved giving omega-3 fatty acids supplements to patients after heart surgery to see if it would improve vascular function, but they could not interest cardiologists in the project.
Power of flavonoids
Things are different now, the Englers say. The medical community has a better perception of the importance of nutrition in health and disease. Mary believes consumers are driving the interest. “People are interested in being in charge of their own health and eating right,” she says. She got the idea for the chocolate study after noting research that showed diets high in fruits and vegetables may help protect against heart disease. She researched foods and beverages high in flavo- noids, which intrigued her as much as omega-3 fatty acids. Flavonoids are anti-oxidant chemicals believed to prevent oxidation of low-density lipoprotein (LDL), the so-called “bad cholesterol” that is the early step of atherosclerosis in the arteries. Dark chocolate, she found, contained considerably more flavonoids and was a more powerful antioxidant than any other food or beverage including berries, spinach, Brussels sprouts red wine, or tea.
She designed a randomized, placebo controlled, double-blind study to see what effect high-flavonoid dark chocolate had on blood flow. Eleven lucky subjects ate a 1.6-ounce bar of dark, flavonoid-rich chocolate every day. Ten others ate an identical low-flavonoid bar. After two weeks, the research team measured the diameter of the subjects’ arteries and discovered a statistically significant improvement in endothelial function the ability of the artery to dilate and an indicator of vascular health in those who had eaten the flavonoid rich chocolate. They also saw an eightfold increase of the chocolate flavonoid epicatechin, in this group.
The results make sense, Mary says, when you consider that flavonoids found in fruits and vegetables come from plants and sg does chocolate, derived from the cocoa bean. Until recently most chocolate was processed in a way that destroyed from 25% to 50% of its flavonoids. Now some companies are changing the way they process chocolate to preserve as much as 70% to 95% of the flavonoids. Chocolate with 70% or more cocoa content will be high in flavonoids, Mary says. I wanted to make sure that (the chocolate study) didn’t come across as frivolous or that this was just another fun study she says. “Everything was gold standard top of the line. I wanted to make sure the science was clearly evident.” The UCSF School of Nursing funded the study, and the American Cocoa Research Associa-tion, a trade organization, provided identical high and low-flavonoid dark- chocolate Dove Bars.
The Englers’ study was the longest one to show improvement in vascular function
from eating flavonoid-rich dark chocolate daily over an extended period of time, Mary says. Previous studies showed benefits either after a single dose or several doses of chocolate over a few days, she adds. A study in Greece, done after the Englers’ study, showed improved blood vessel function for about three hours after subjects ate 100 grams of dark chocolate. That study has led at least one German insurance company to recommend its clients eat small amounts of dark chocolate regularly. Scientists writing for the British Medical Journal included dark chocolate as part of a “polymeal” that also consists of red wine, fish, fruits and vegetables, garlic, and almonds, and’ estimate that people who eat these foods every day — with the exception of fish, which they should only eat four days a week — may cut their risk of heart disease by 76%.
Moderation is best
Recommendations on chocolate consumption will not be coming anytime soon from the American Heart Association, says Linda Van Horn, RD, PhD, a professor of preventative medicine at Northwestern University in Chicago and a member of the American Heart Association Nutrition Committee. Van Horn has seen the Englers’ chocolate study and believes it is a good one, but she says much more research on much larger groups of people is needed before chocolate can be recommended as a heart-healthy food. Also, she notes, chocolate is high in calories, contains fat and sugar, and could contribute to obesity if consumed in large amounts. “No one would suggest that eating chocolate in moderation is a bad thing for you, but we’re not going to go out on a limb and say it’s a good thing for you, either,” she says.
The Englers are quick to emphasize the importance of the “in moderation” aspect of any chocolate-consumption recommendations. “Even though we have a long way to go before we understand all of chocolate’s effects,” Mary says in the press release accompanying the study, “for now, there’s little doubt that in moderation and in conjunction with a healthy, balanced diet and exercise~ we can enjoy and even benefit from — moderate amounts of high-flavonoid dark chocolate.”
The Engers believe flavonoids could eventually prove as beneficial as omega-3 fatty acids have turned out to be. They felt vindicated when European studies came out showing how omega-3 fatty acids benefited the heart and vascular system in many ways. They note that food producers are adding omega-3s to eggs, orange juice, infant formula, and other products, including puppy chow. In a literature review, published last November , 2004, in Nutrition Research, the Englers listed studies supporting a variety of vascular benefits from cocoa flavonoids, including antioxidant properties, improvement in endothelial function, lowered blood pressure, decreased platelet activation which can prevent clotting and modulation of immune function and inflammation.
“We’re just at the tip of the iceberg with flavonoid research,” Mary says. Current results show a need for larger and more long-term studies on the effects of flavo-noids in chocolate, cocoa, and other foods and beverages, she says. “We have our research cut out for us for a number of years,” notes Marguerite. Besides the chocolate studies, the Englers have recently published studies, with Marguerite as the lead author, showing how antioxidant vitamins C and E and the omega-3 fatty acid DHA improve endothelial function in children with high cholesterol. They have a grant from National Institute for Nursing Research to look at early nutritional interventions in children who have a family history or other risk markers for heart disease.
The Englers’ work and the public attention it has received are inspiring to students and other nurse researchers, Dracup says. “We welcome that attention to nursing research,” she adds. “In their research, nurses are usually not discovering the cause of diseases or a new form of intervention.” Most nursing research focuses on symptom management, reducing risk factors, and managing chronic illness. “That’s not the stuff of high drama.” The Englers say they have always been chocolate connoisseurs, though Mary says she has converted to eating dark instead of milk chocolate as a result of the study. Marguerite has always preferred dark chocolate. When they were in high school, their favorite candy was, naturally, M&M’s. They even dressed as M&M’s one Halloween. Mary was plain; Marguerite was peanut. “Who’d have predicted,” says Mary, “that years later we’d be doing a chocolate study.” and finding out that, at least in moderation, it may actually be good for you.
***Cathryn Domrose is a staff writer for Nurseweek.
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(February 14, 2005 / Vol. 6, No. 4)
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