Every five years, the federal Department of Agriculture and Department of Health and Human Services revise their Dietary Guidelines for Americans, a publication that sets the direction for federal nutrition-education programs. In an age when aggressive government agencies in places like New York City seek a greater hand in shaping Americans diets, the next set of guidelines, published later this year, could prove more controversial than usual because increasing scientific evidence suggests that some current federal recommendations have simply been wrong. Will a public-health establishment that has been slow to admit its mistakes over the years acknowledge the new research and shift direction? Or will it stubbornly stick to its obsolete guidelines?
The crux of the controversy is the quantity of fat and carbohydrates that we consume and how it influences our cardiac health. As a recent review of the latest research in Scientific American pointed out, ever since the first set of federal guidelines appeared in 1980, Americans heard that they had to reduce their intake of saturated fat by cutting back on meat and dairy products and replacing them with carbohydrates. Americans dutifully complied. Since then, obesity has increased sharply, and the progress that the country has made against heart disease has largely come from medical breakthroughs like statin drugs, which lower cholesterol, and more effective medications to control blood pressure.
Researchers have started asking hard questions about fat consumption and heart disease, and the answers are startling. In an analysis of the daily food intake of some 350,000 people published in the March issue of The American Journal of Clinical Nutrition, researchers at the Childrens Hospital Oakland Research Institute found no link between the amount of saturated fat that a person consumed and the risk of heart disease. One reason, the researchers speculate, is that saturated fat raises levels of so-called good, or HDL, cholesterol, which may offset an accompanying rise in general cholesterol. A few weeks later, researchers at Harvard released their own analysis of data from 20 studies around the world, concluding that those who eat four ounces of fresh (not processed) red meat every day face no increased risk of heart disease.
According to Scientific American, growing research into carbohydrate-based diets has demonstrated that the medical establishment may have harmed Americans by steering them toward carbs. Research by Meir Stampfer, a professor of nutrition and epidemiology at Harvard, concludes that diets rich in carbohydrates that are quickly digestiblethat is, with a high glycemic index, like potatoes, white rice, and white breadgive people an insulin boost that increases the risk of diabetes and makes them far more likely to contract cardiovascular disease than those who eat moderate amounts of meat and fewer carbs. Though federal guidelines now emphasize eating more fiber-rich carbohydrates, which take longer to digest, the incessant message over the last 30 years to substitute carbs for meat appears to have done significant damage. And it doesnt appear that the government will change its approach this time around. The preliminary recommendations of a panel advising the FDA on the new guidelines urge people to shift to plant-based diets and to consume only moderate amounts of lean meats, poultry and eggs.
The public-health establishment has been sluggish about reversing course before. Starting in the 1970s, for instance, the American Heart Association advised people to reduce drastically their consumption of eggs as part of a goal to limit total cholesterol intake to 300 milligrams a day (a single egg can have 250 milligrams). The recommendation, seconded by government and other public-health groups, prompted a sharp drop in the consumption of eggs, a food that nutritionists praise as low in calories and high in nutrients. In 2000, the AHA revised its restrictions on eggs to one a day (from a onetime low of three a week), but it also recommended reducing consumption of other cholesterol-heavy foods to compensate. Similarly, the federal governments dietary guidelines still recommend intake of no more than 300 milligrams of cholesterol daily, which makes egg consumption difficult unless one excludes most other animal products. To what purpose? A 2004 article in The Journal of Nutrition that looked at worldwide studies of egg consumption noted that the current restrictions on eating eggs are unwarranted for the majority of people and are not supported by scientific data.
More and more, the history of dietary guidelines that our public-health authorities promulgate resembles the Woody Allen comedy Sleeper, in which the main character, awaking from a centuries-long slumber, learns that every food we once thought bad for us is actually good, starting with steak and chocolate. But you wouldnt know that from government experts increasing efforts to nudge us into their approved diets. In 2006, New York City passed the nations first ban on the use of trans fats by restaurants, and other cities followed suit, though trans fats constitute just 2 percent of Americans caloric intake. Now the Bloomberg administration is trying to push food manufacturers nationwide to reduce their use of saltand the nutrition panel advising the FDA on the new guidelines similarly recommends reducing salt intake to a maximum of 1,500 milligrams daily (down from 2,300 a day previously). Yet Dr. Michael Alderman, a hypertension specialist at Albert Einstein College of Medicine, observed in the New York Times that because sodium is an essential component of our diets, the citys effort amounts to a giant uncontrolled experiment with the publics health that could have unintended consequences. And in 2006, Harvard Medical School professor Norman Hollenberg concluded that while some people benefit from reduced salt intake, the evidence is too inconsistent and generally too small to mandate policy decisions at the community level.
As increasingly sophisticated medicine focuses on tailoring therapies to individual needs, sweeping public pronouncements on health have become outdated at best and dangerous at worst. The best advice that government can give citizens is to develop their own diet and exercise regimes, adapted to their own physical circumstances after consultation with their doctors.