Progressives tend to believe that government knows best. The unfolding fiasco over government nutrition misinformation should give them pause.
For years now the Centers for Disease Control and Prevention have been recommending that "everyone age 2 and up should consume less than 2,300 milligrams (mg) of sodium each day. Some groups of people should further limit sodium intake to 1,500 mg per day, including adults age 51 or older, all African Americans, and anyone with high blood pressure, diabetes, or chronic kidney disease." Recent studies now suggest that this advice is killing more people than it's saving.
For example, New England Journal of Medicine published a study in August 2014 reported that that people who consume less 1,500 milligrams of sodium (about 3/4ths of a teaspoon of salt) are more likely to die than people who eat between 3,000 to 6,000 milligrams of sodium per day (1.5 and 3 teaspoons of salt).
Red meat has long been a government dietary no-no associated with higher risk of cardiovascular disease and colon cancer. Two recent studies find these claims to be overblown. A 2013 European study that followed nearly 450,000 people since the early 1990s found no significant increase in mortality among consumers of red meats, but higher risk of mortality for those who eat processed meats. A 2013 American study that followed 18,000 participants since the mid-1980s reported, "Meat consumption was not associated with mortality."
The food nannies over at the Center for Science in Public Interest famously called fettuccine alfredo a "heart-attack-on-a-plate" because of the large amounts of saturated fats in some restaurant versions of the dish. Americans have long been told to avoid eating milk, cheese, butter, yogurt, and bacon.
A 2010 study in the Journal of Clinical Nutrition reported that its "meta-analysis of  prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of [coronary heart disease, stroke, or cardiovascular diease]." A 2014 meta-analysis of 72 studies of saturated fat consumption also found that the "current evidence does not clearly support cardiovascular guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of total saturated fats." In addition, a 2014 Norwegian study in the Journal of Nutrition just reported "there was no association between dietary intake of SFA [saturated fatty acids] and incident coronary events or mortality in patients with established CAD [cardiovascular disease].
And then, of course, last week, the federal government's Dietary Guidelines Advisory Committee walked back long-standing advice to cut back on the consumption of dietary cholesterol. High cholesterol foods like eggs, shrimp, and lobster are no longer verboten. As the Washington Post reported,
The group’s finding that cholesterol in the diet need no longer be considered a “nutrient of concern” stands in contrast to the committee’s findings five years ago, the last time it convened. During those proceedings, as in previous years, the panel deemed the issue of excess cholesterol in the American diet a public health concern.
The finding follows an evolution of thinking among many nutritionists who now believe that, for healthy adults, eating foods high in cholesterol may not significantly affect the level of cholesterol in the blood or increase the risk of heart disease.
Most of the government's recommendations were derived from "consensus statements" based largely on the results of observational epidemiological studies. The new revisions tend to be based on prospective epidemiological studies and random controlled trials. Observational studies may be good at developing hypotheses, but they are mostly not a good basis for making behavioral recommendations and imposing regulations.
Other areas in which observational epidemiology studies have misled regulators and the public are claims that exposures to trace amounts of synthetic chemicals are major causes of cancer and endocrine disruption. But those are topics for another time.
Finally, the new food findings are not a license to pig out. Eating fewer calories (I try, I do try) and consuming more fruits and vegetables is most likely good advice.
For more background see my colleague Jacob Sullum's prescient 2003 article, "The Anti-Pleasure Principle: The "food police" and the pseudoscience of self-denial."