An Industry-Funded Diet Study the Media Is Sure to Love
Want to lower your cholesterol? New research tells you how—but it doesn't really say anything new about how to eat.
The latest issue of JAMA has a paper on a "portfolio" of dietary means to reduce blood cholesterol levels.
The paper is likely to get lots of press because it concludes that consuming the "portfolio"--a combination of plant sterols, soy protein, viscous fibers, and nuts--does a better job of lowering LDL-cholesterol (the "bad" kind) than does dietary advice to reduce saturated fat.
The paper is unusually difficult to read. I interpret the study in part as a drug trial.
One look at the Abstract and I immediately suspected that this study must have been sponsored by a maker of plant sterol margarines.
Plant sterols are well established to reduce blood cholesterol levels. Unilever, which makes Take Control margarines, is one of the sponsors.
As I interpret it, the study shows:
- Advising people who weigh an average of 76 kg (167 pounds) to consume a healthy diet doesn't work. Study subjects did not change their diets by much during the six months of the trial. No news here.
- Advising people to add things to their diets has a better chance of succeeding than advising taking things away (like saturated fat).
- All of the portfolio items have been established to lower blood cholesterol in clinical trials, although the evidence for soy protein seems a bit iffy these days.
- The study does not distinguish between the relative effects of soy protein, fiber, or cholesterol-lowering margarines. If soy is eliminated, that leaves fiber and margarines. I'm guessing the margarines were the critical factor. Hence: a partial drug trial.
- And because my book on calories is coming out next March, I must point out that the study groups reported losing losing small amounts of weight, which means they must also have reduced their calorie intake. Weight loss alone should help with blood cholesterol.
The take-home message: if you really do substitute nuts, sources of fiber, and healthy foods for whatever less healthful foods you used to eat, you ought to get some health benefit, with or without plant sterol margarines.
QED: Healthy diets produce health benefits.
It's always nice to see that confirmed.
This post also appears on Food Politics.