Mediterranean Diets Beat Low-Fat for CVD Prevention
by Shelley Wood; Feb 25, 2013
Loma Linda, CA — A Mediterranean diet supplemented with either extra virgin olive oil or mixed nuts may cut the risk of cardiovascular events by as much as 30% in subjects at high risk of developing heart disease, as compared with people advised to eat a reduced-fat diet [1].
Those are the key findings from the randomized controlled PREDIMED primary-prevention trial presented here at the International Congress on Vegetarian Nutrition.
The Mediterranean diet already reigns supreme in secondary prevention of CV events. PREDIMED, which looked at diet effects on hard clinical end points, carves out an important role for this dietary eating pattern in primary prevention.
“These results support the benefits of the Mediterranean diet for CV risk reduction [and] are particularly relevant given the challenges of achieving and maintaining weight loss,” investigators write in a paper published in advance of the presentation in the New England Journal of Medicine. PREDIMED was led by Dr Ramón Estruch (Hospital Clinic, Barcelona, Spain) and Dr Miguel Angel Martínez-González (Clinical Universidad de Navaraa, Pamplona, Spain).
Commenting on the study for heartwire , Dr Marc Gillinov (Cleveland Clinic, OH), who was not involved in the study, pointed out that there are very few studies of any diets that are rigorously designed and that address hard clinical outcomes. “This randomized controlled trial is by far the best in class when it comes to dietary studies. We should take its results seriously: if you have risk factors for cardiovascular disease–and the majority of adult Americans do–your best bet is to follow a Mediterranean diet.”
PREDIMED: Oil and Nuts Over Fat Restriction
PREDIMED enrolled 7447 men and women ranging in age from 55 to 80 years, none of whom had established cardiovascular disease but who were at high CV risk. Subjects were randomized to one of two Mediterranean diet groups (one supplemented with olive oil, the other with nuts) or to a control diet wherein subjects were advised to try to reduce dietary fat.
Patients in the Mediterranean-diet groups were invited to regular dietary training sessions; by contrast, those in the control group were, for the first three years, sent leaflets explaining a low-fat diet. After a protocol amendment at the three-year mark, low-fat-diet patients were also invited to regular group sessions and offered personalized advice at the same level of intensity as the Mediterranean groups.
The study was stopped when an interim analysis at 4.8 years revealed a clear signal of benefit among subjects eating the Mediterranean diets. In the olive-oil and mixed-nut Mediterranean diet groups, the primary end point (MI, stroke, or CV death) was reduced by 30% and 28% respectively, as compared with the control group.
Study dropouts, meanwhile, were twice as common in the control diet group as in the Mediterranean diet group (11.3% vs 4.9%). “Favorable trends” were seen for both stroke and MI rates among subjects eating the Mediterranean diet, but numbers were too low to be relevant statistically. A total of 288 subjects experienced an event in the study: 96 events in the olive-oil group, 83 in the nut group, and 109 in the control group.
Of special note, subjects randomized to the Mediterranean diets were not told to reduce calories, a major barrier to success in many dietary interventions, particularly the long-supported “low-fat” approach.
Good Fat and Bad
In an email to heartwire , Estruch highlighted the importance of differentiating between different types of fat “Animal fat should be avoided,” he said, whereas “vegetal fats–extra virgin olive oil and nuts–should be recommended [within] a healthy food pattern such as the Mediterranean diet.”
Asked whether the findings would be applicable to other parts of the world where saturated fats are such a common component of everyday eating, Estruch stressed the importance of education.
“People should know that the Mediterranean diet is a diet healthier than others and should know the key components of this food pattern. The plan should be to increase the intake of the key foods (vegetables, fruit, nuts, fish, legumes, extra virgin olive oil, and red wine in moderation), also increase the intake of white meat, and decrease the intake of red and processed meat, soda drinks, whole dairy products, commercial bakery goods, and sweets and pastries.”
He continued: “To achieve a score of 14 in the 14-item adherence scale to traditional Mediterranean diet [laid out in a supplemental appendix in the paper] is more or less impossible, but to upgrade two to three points in this score is enough to reduce your cardiovascular risk by 30%.”
Gillinov, in turn, pointed out that there are no data of a similar quality supporting a low-fat diet, although these have long been promoted by physicians and professional medical groups. “The Mediterranean diet contains moderate quantities of fat, and it clearly wins in this trial of primary prevention,” he said.
Dr Steven Nissen , also of the Cleveland Clinic, was even more effusive, calling PREDIMED “a spectacular study that was extremely difficult to perform.”
“The findings are compelling and should alter the dietary advice we give patients. The currently popular ultralow-fat diets . . . are clearly not best for patients,” he told heartwire in an email. “The standard AHA-recommended diet should be modified to reflect these findings: fat is not the problem with the American diet, we just eat the wrong types of fats.”
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High-Fructose Corn Syrup Linked to Diabetes
by Brenda Goodman, MA Nov 27, 2012
Countries that mix high-fructose corn syrup into processed foods and soft drinks have higher rates of diabetes than countries that don’t use the sweetener, a new study shows.
In a study published in the journal Global Health, researchers compared the average availability of high-fructose corn syrup to rates of diabetes in 43 countries.
About half the countries in the study had little or no high-fructose corn syrup in their food supply. In the other 20 countries, high-fructose corn syrup in foods ranged from about a pound a year per person in Germany to about 55 pounds each year per person in the United States.
The researchers found that countries using high-fructose corn syrup had rates of diabetes that were about 20% higher than countries that didn’t mix the sweetener into foods. Those differences remained even after researchers took into account data for differences in body size, population, and wealth.
But couldn’t that mean that people in countries that used more high-fructose corn syrup were just eating more sugar or more total calories?
The researchers say no: There were no overall differences in total sugars or total calories between countries that did and didn’t use high-fructose corn syrup, suggesting that there’s an independent relationship between high-fructose corn syrup and diabetes.
“It raises a lot of questions about fructose,” says researcher Michael I. Goran, PhD, co-director of the Diabetes and Obesity Research Institute at the Keck School of Medicine at the University of Southern California, in Los Angeles. Although the study found an association, it doesn’t establish a cause/effect relationship.
The Industry Responds
Not everyone is convinced.
Audrae Erickson is president of the Corn Refiners Association, an industry group that recently petitioned the FDA to change the name corn syrup to corn sugar on ingredient lists.
“Just because an ingredient is available in a nation’s diet does not mean it is uniquely the cause of a disease,” she says in a prepared statement.
“There is broad scientific consensus that table sugar and high-fructose corn syrup are nutritionally and metabolically equivalent,” Erickson says.
“It is, therefore, highly dubious … without any human studies demonstrating a meaningful nutritional difference between high-fructose corn syrup and sugar — to point an accusatory finger at one and not the other,” she says.
On that point, nutritionists who were not involved in the research think the corn industry is right.
Marion Nestle, PhD, MPH, professor of food, nutrition studies, and public health at New York University, says the study “is based on a questionable and highly debatable premise: that high-fructose corn syrup is significantly different in its physiological effects from sucrose, or table sugar.”
Both table sugar and high-fructose corn syrup are a mixture of two simple sugars — fructose and glucose.
Nestle says studies show that the body responds to table sugar and high-fructose corn syrup the same way.
The bottom line, she says, is that too much of any kind of sugar isn’t healthy, no matter where it comes from.
It’s More Complicated?
But Goran says the problem is more complex.
There’s some scientific evidence that the body treats fructose differently than glucose. Table sugar is about half fructose and half glucose. The percentage of fructose in high-fructose corn syrup isn’t disclosed on food labels, but it’s thought to range from 42% to 55%. But it may be even higher than that. In a study published in 2011 in the journal Obesity, Goran found the percentage of fructose in drinks sweetened with high-fructose corn syrup ranged from 47% to 65%.
“I know there’s a lot of consumer confusion about fructose: It’s a fruit sugar; it’s healthy; it’s already in sugar,” he says. But, again, it’s not that simple.
Goran thinks there’s a big difference between fructose in fruit — where it’s paired with fiber, which slows down its absorption — and fructose that’s refined into syrup.
“There are lots of other aspects of the way fructose is handled by the body which are different than glucose that make it metabolically dangerous for the body,” he says.
SOURCES:
Goran, M. Global Public Health, Nov. 27, 2012.
Michael I. Goran, PhD, co-director, Diabetes and Obesity Research Institute at the Keck School of Medicine, University of Southern California, in Los Angeles.
Audrae Erickson, president, Corn Refiners Association, Washington, D.C.
Marion Nestle, PhD, MPH, professor of food, nutrition studies and public health, New York University, New York City.