SA Forum is an invited essay from experts on topical issues in science and technology.
Recently Americans heard some fantastic-sounding news: A federally appointed panel of experts announced that we can stop worrying about cholesterol. Even more surprising, the news is true—sort of.
Every five years the U.S. Department of Health and Human Services is legally required to publish a new revision of a government document called the Dietary Guidelines for Americans. Its purpose is to help set a course for the country’s future food and nutrition policies. To ensure that the book’s advice will be as accurate and up-to-date as possible, a special Dietary Guidelines Advisory Committee (DGAC) has been established to read and summarize the latest research on a wide array of topics, ranging from dietary patterns to food sustainability. Nevertheless, parts of the guidelines have remained essentially the same. For one thing, every edition since the first one has advised Americans to consume less cholesterol.
Until now, that is. The 2015 Dietary Guidelines are still being drafted and won’t be published until later this year. But the advisory committee’s latest 571-page report (pdf) has already made headlines by pointedly dropping the usual call for a reduction in dietary cholesterol: “Previously, the Dietary Guidelines for Americans recommended that cholesterol intake be limited to no more than 300 milligrams per day. The 2015 DGAC will not bring forward this recommendation because available evidence shows no appreciable relationship between consumption of dietary cholesterol and serum cholesterol, consistent with the conclusions of the AHA/ACC [American Heart Association/American College of Cardiology] report.”
Unfortunately, some news media misconstrued those two sentences as meaning that—contrary to decades of past physiological research—the amount of cholesterol an individual ingests has nothing to do with the level of cholesterol in that individual’s blood. But the report’s authors meant nothing of the kind. The fact is that the DGAC’s mandate was to focus solely on the country’s present-day dietary habits. And those dietary habits are not what they were when the guidelines began. Decades of persistent warnings against dietary cholesterol have reduced the average American adult’s intake to approximately the recommended 300 milligrams a day. Even though our bodies produce cholesterol whether or not we consume any, for most of us, if we eat more, our bodies sense that and make less. Nevertheless, the levels of blood cholesterol continue to be an ongoing subject of cardiovascular concern. No responsible health professional thinks we should return to the unrestrained rate of consumption of dietary cholesterol that was prevalent a half century ago. It’s also important to note that some individuals seem to be particularly sensitive to dietary cholesterol or are at very high risk of developing cardiovascular disease; they should follow their doctors’ instructions and restrict their intake.
And in light of the public uproar over the committee’s shift on dietary cholesterol, it’s also worth mentioning that the DGAC report stands by previous guidelines’ recommendations for Americans to minimize their consumption of saturated fat. These days that substance, rather than dietary cholesterol, appears to be the big threat to America’s cardiovascular health. The answer is not merely to avoid saturated fat; it’s also to steer clear of refined carbohydrates, like sugar and white bread. Instead, the report says (along with the AHA and others) we need to replace those calories that come from saturated fat with polyunsaturated fats. As described in the committee’s report, a heart-healthy diet for active American adults is rich in vegetables, fruit, whole grains, seafood, legumes and nuts; moderate in low- and nonfat dairy products and alcohol (among adults); lower in red and processed meat; and particularly low in sugar-sweetened foods and beverages and refined grains.
Beyond confirming such well-established medical wisdom, the committee’s chief assignment was to help compile the necessary research for the guidelines’ authors, not to take over the actual writing. At this point there’s no telling what the finished version of the 2015 guidelines will say, whether about cholesterol consumption or about any other aspect of the American diet. In any case, it should be remembered that the guidelines are primarily a tool for policy makers. They were never designed to be a nutritional protocol for the treatment of high-risk individuals. The hope is only that each new edition will help to make America a healthier country.
Alice H. Lichtenstein is vice chair of the Dietary Guidelines Advisory Committee, the Stanley N. Gershoff Professor of Nutrition Science and Policy and director and senior scientist of the Cardiovascular Nutrition Laboratory at Tufts University.