By MICHELLE L. BRANDT
Among the things that participants learned at Stanford's recent Controversies in Cardiovascular Nutrition conference was that the event was aptly named. Presenters on Saturday had strong, often conflicting opinions and you practically needed a flow chart to keep up with the dietary recommendations and disease implications.
Aside from controversy, audience members — three-fourths of whom were medical professionals — were treated to lively debate, comedic presentations and detailed descriptions of heart-healthy diets. "We designed the conference so everyone would walk away with a sense of what's best for them or their patients," said John Cooke, MD, PhD, associate professor of medicine and event organizer.
Although presenters at the all-day conference discussed issues ranging from nutritional supplements to medical ethics, much of the time was spent on cardiovascular benefits of three categories of diets.
Dean Ornish, MD, clinical professor of medicine at UCSF, opened by discussing the benefits of his ultra-low-fat, no-animal-protein diet. He presented studies showing it can reduce cardiac disease risk, pointing to research from Robert Vogel, MD, director of clinical vascular biology at the University of Maryland. The studies, which Vogel later presented, show that a single meal high in saturated fat can impair the endothelium (lining of the blood vessels) within one hour. This can boost the risk of a cardiac event.
Gerald Reaven, MD, professor of medicine at Stanford, followed Ornish, sharing his reservations about the low-fat approach. He said the diet involves replacing saturated fats (mostly from animal sources) with carbohydrates, which can have dangerous affects on the roughly 50 million Americans who have hyperinsulinemia. When these people consume carbohydrates, their bodies produce too much insulin, which can lead to hypertension, diabetes, decreased levels of "good" (HDL) cholesterol and increased heart disease risk.
"Given that 25 percent of Americans are insulin-resistant, I see no reason to run the risk of giving patients these problems," he said of the low-fat diet.
Reaven also noted that Ornish's diet includes lifestyle changes, such as smoking cessation, weight loss, exercise and stress management. These factors — not the diet itself — may be responsible for cardiac benefit. "Ornish's evidence was not based on diet alone," he said. "It's impossible to evaluate the independent effect of diet when multiple changes are being made."
Penny Kris-Etherton, PhD, professor of nutrition at Penn State University, later presented her case for a moderate-fat diet, such as the Mediterranean diet (which is high in vegetable protein and moderate in carbohydrates). She discussed the health benefits of unsaturated fats (mostly from plant sources) and pointed to studies showing that replacing this type of fat with carbohydrates increases the risk of heart disease. She said a low-fat diet doesn't typically allow for the consumption of these fats, including beneficial Omega-3 fatty acids.
Reaven also said the moderate approach is easier for individuals to adhere to than low-fat diets. "There is substantial evidence that a more moderate-fat diet is easier for people to stay on and lose weight with," he said.
Event panelists also took time to discuss the popular high-protein, low-carbohydrate diet, known as the "Atkins Diet." During a recent conversation, Robert Atkins, MD, founder and medical director of the Atkins Center for Complementary Medicine, explained that his angle takes the approach of reducing intake of carbohydrates for hyperinsulinemic patients one step further.
"I have scientific studies that show that an even greater lowering of dietary carbohydrates has benefit for these types of patients," he said. "I hope medical professionals will recognize this is a therapeutic option that deserves an opportunity to be utilized."
Atkins didn't attend the conference, but Ornish critiqued his diet anyway, explaining that a high-protein, low-carbohydrate diet is high in disease-causing substances and low in disease-preventing substances. Cooke also mentioned studies showing red meat eaters experience twice the number of cardiac events as others.
By day's end, experts were still quibbling over details, but they seemed to have reached one consensus: the importance of adopting heart-healthy lifestyles. As Ornish noted at the outset, "We agree on much more than we disagree."
Heart program urges public self-advocacy (2/6/02)
Stanford Report, May 8, 2002