This story was about a study comparing a special vegetarian diet containing a “portfolio” of cholesterol-lowering foods (e.g. nuts, soy, margarines fortified with plant sterols) with standard dietary advice for preventing heart disease (e.g. cut out saturated fat). There was plenty to like about this story, including comments from two excellent independent sources which added valuable context to the piece. The story also makes the very important point that this study looked only at a surrogate marker of heart disease risk, LDL cholesterol, and not actual heart disease outcomes. But the story didn’t provide crucial information about costs or availability of the diet components and it didn’t fairly describe how difficult it would be for most people to maintain this kind of diet. These mistakes are compounded by a glaring misinterpretation of the study which is trumpeted in the headline — i.e. that the diet tested in the study lowered LDL cholesterol “more than statin drugs.”
Many people at risk of heart disease don’t want to take cholesterol-lowering drugs, can’t take them because of troubling side effects, or don’t achieve their targets on drug therapy alone. Others may have cholesterol levels above target but below the range where statin therapy is indicated. Diet-based interventions such as this “portfolio diet” represent an important potential alternative for these patients.
Will following this special diet cost patients more than what they spend on food today? A look at some of the pricey components — soy milk, tofu, supplemented margarine, etc — suggests that it might. That’s an important consideration that the story doesn’t address.
The story is badly flawed by its suggestion that the portfolio diet is more effective than statin drugs for lowing LDL cholesterol. The headline claims that the diet may be the “best” medicine for lowering LDL and the subhead says the diet lowers LDL “more than statin drugs.” In the text, it is suggested that the authors of the study said the diet can lower LDL cholesterol to levels “half that seen by many patients who take statins.” The study authors said no such thing. They said that the cholesterol reduction observed with the diet was about half that seen with some early statin drugs, meaning that the drugs are about twice as effective as the diet for lowering LDL. Newer statin drugs are quite a bit more effective for lowering LDL. This is a critical misreading of the study.
The story did not mention potential harms of the diet. Although those on the portfolio diet did not have significantly more adverse events than those on the control diet, some allergy-type reactions did occur that were probably related to the diet components (soy, tree nuts). The story should have made some reference to safety.
Mixed bag here, which we’ll ultimately call satisfactory, as there was sufficient detail for the reader to get a sense of the intervention, the participants, and the main results. Also, the story earns high marks for explaining that LDL cholesterol is a surrogate endpoint and that the study did not actually determine whether the diet resulted in fewer heart attacks or other cardiovascular problems. This is a crucial point, because we do have good evidence that statin drugs, given to the right people, help prevent heart attacks. Ultimately, we care a lot more about heart attacks than we do the numbers on a laboratory test.
But the story is quite misleading when it suggests that understanding and implementing the portfolio diet in everyday life is “pretty easily done.” Implementing the diet is one thing, but staying on it is another. As the researchers acknowledge in their paper, the diet was “complex” and the study had a “high” attrition rate of 22.6% after only 6 months. That rate surely would have increased with longer duration of follow-up. Many other studies attest to the difficulty people have staying on healthy diets that are arguably less demanding than this plan, which lists “tofu bake with ratatouille” as a representative dinner. And if people can’t stay on the diet, they won’t see the benefit.
The story didn’t exaggerate the impact of heart disease or try to sell treatment to those who don’t need it.
We applaud the inclusion of comments from two well-known independent experts on diet and heart disease, Steve Nissen and Walter Willett. However, the story did not adequately identify funding conflicts. The study was partially funded by Unilever, which makes margarine containing plant sterols (one of the cholesterol-lowering components of the portfolio). In addition, many of the study authors reported receiving grant funding or had other relationships with Unilever and other organizations with a commercial interest in the study.
The study being covered was a comparison of the portfolio diet with standard dietary advice for preventing heart disease. Comparisons with statins (though erroneous) are also made, but since the points for this problem were docked elsewhere, we’ll award a satisfactory here.
Although most of the foods consumed by study participants are probably available in most areas, those in poor urban and rural areas may have trouble finding what they need to eat a nutritionally adequate diet when following the portfolio principles. (The diet relies on a lot of soy-based meat replacements.) A bigger problem may be finding a health professional who can instruct patients in how to follow the diet in a healthful way. Doctors in the U.S. are not reimbursed for providing dietary advice, and so don’t have much incentive to counsel patients on this kind of diet plan. Also, many uninsured patients do not have access to a dietitian who could do even the “less intensive” two-session intervention described in the story. The story should have at least mentioned some of these issues.
The story doesn’t directly refer to previous studies of the portfolio diet, which have reported similar benefits. And thus it may give readers the impression that this approach is more novel than is actually the case. On the other hand, the story does note that the various components of the diet have well known “cholesterol-busting” properties. A close call here, but since the story is factually correct when it says this was the first study to test the diet in a real-world comparison (even if it doesn’t mention the previous studies), we’ll give the benefit of the doubt.
The story was not based on a news release.