Dietary Habits May Aid Secondary Prevention in Patients With Stable CHD
For people with stable coronary heart disease, consuming a diet with little meat but rich in whole grains, fruits, vegetables, legumes, fish, and moderate amounts of alcohol—a so-called Mediterranean dietary pattern—may offer protection against major adverse coronary events. But avoiding refined grains, sweets and desserts, sugared drinks, and deep fried foods—patterns typical of a Western diet—may not matter, researchers reported online April 24, 2016, in the European Heart Journal.
“The take-home message is that we probably need to be encouraging people to eat healthy foods, as the focus of our dietary advice,” lead author Ralph A.H. Stewart, MBChB, MD (Auckland City Hospital, New Zealand), told TCTMD. Instead, he said, it seems that the study participants, all of whom had been given dietary guidance after experiencing their coronary event, were mainly focusing their energies on reducing unhealthy foods.
The good news these findings hold for secondary prevention, Stewart noted, is that “people might be a bit more receptive to sort of a positive message than the kind of ‘don’t do this, don’t do that’ message, which is often what dietary advice is taken as.”
Using data from the STABILITY trial, originally designed to test the efficacy of the drug darapladib at reducing major adverse cardiovascular events, Stewart and colleagues analyzed self-reported dietary patterns for more than 15,000 patients from 39 countries who had stable CHD. They calculated scores to represent to what degree each individual consumed a Mediterranean or Western diet.
At a median follow-up of 3.7 years, MACE rates ranged from a low of 7.3% to a high of 10.8% among patients consuming a more versus less Mediterranean-like diet. The differences remained significant after adjustment for geographic region, country income, education level, age, smoking, HDL cholesterol level, renal function, and polyvascular disease category.
There was no association between diets that leaned “Western” in either unadjusted or adjusted models, the researchers reported.
“Greater consumption of healthy foods may be more important for secondary prevention of coronary artery disease than avoidance of less healthy foods typical of Western diets,” they conclude.
All Roads Lead to Rome
Paul F. Jacques, DSc (Tufts University, Boston, MA), director of the nutritional epidemiology program at the Jean Mayer USDA Human Nutrition Research Center on Aging, expressed reservations to TCTMD. Commenting on the study, he pointed out that before drawing any firm conclusions, he would need to know more about the validity of the dietary assessment tool used in the study. This is especially true, he said, because the questionnaire was used in such a wide variety of countries and cultures.
People who score high on the Mediterranean diet in the United States versus, for example, China, “are probably eating quite different dietary patterns to achieve that high score,” Jacques explained, adding that “it’s not necessarily a ‘Mediterranean diet’ per se.” Nor did the study assess the influence of fat intake, he noted.
Moreover, Jacques said, “the fact that the Western diet score is not inversely correlated with the Mediterranean diet score I think says that there are other complexities here that aren’t getting captured in these two relatively simple scores.”
To TCTMD, Stewart explained, “The study was designed to evaluate a ‘Mediterranean diet score,’ which has been associated with a lower risk of heart disease in a number of other studies,” not what is popularly thought of as the foods eaten in the Mediterranean region. “It is interesting that patients from Mediterranean countries did not have the highest scores” in the study, he noted. “These countries also have much higher rates of coronary artery disease than previously. So as generally used, the term ‘Mediterranean’ could be misleading.”
The dietary pattern evaluated here “includes more fruit, vegetables, and fish, less meat, and modest alcohol,” he said. “In this study we assessed frequency of consumption of these food groups, but the actual diet varied widely depending on geography.” That the findings were consistent across very diverse groups speaks to their generalizability, he said.
“What we’re showing is that broad [Mediterranean] dietary pattern can be achieved in very diverse ways in different parts of the world and those diverse ways are okay,” Stewart said. “They still capture the essence of benefit of what we’ve seen in many other studies of a more focused Mediterranean diet.”
He did acknowledge that the scores were not validated in the traditional sense, in that there was no inquiry into whether what people answered on the questionnaire accurately reflected what they ate. “We weren’t able to do that in this study, although people have done it in other studies with very similar dietary questionnaires and found it’s a reasonable approximation,” Stewart said. “For various reasons, it was imprecise. And in fact that probably means that we actually underestimated the true effect, because of the random noise and error in the measurement. Probably the actual beneficial effect is bigger, but on the other hand, we can’t exclude possible adverse effects of some things because of the imprecision of the dietary tool.”
Stewart RAH, Wallentin L, Benatar J, et al. Dietary patterns and the risk of major adverse cardiovascular events in a global study of high-risk patients with stable coronary heart disease. Eur Heart J. 2016;Epub ahead of print.
- The STABILITY trial and diet substudy were funded by GlaxoSmithKline, and funding to pay the Open Access publication charges for the paper was provided by the company.
- Stewart reports receiving grants and nonfinancial support from GlaxoSmithKline during the conduct of the study.
- Jacques reports no relevant conflicts of interest.