Every five years, the U.S. Department of Agriculture and the Department of Health and Human Services revised their dietary guidelines for Americans, which are intended to set the direction for federal nutrition education programs. 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?
FOR THE RECORD:
Sodium: A July 18 Op-Ed said that a nutrition panel advising the FDA on new dietary guidelines has recommended restricting salt intake to a maximum of 1,500 milligrams daily. It should have said the recommendation was for sodium intake, not salt. —
The crux of the controversy is the quantity of fat and carbohydrates that we consume and how that influences our cardiac health. As a recent review of the latest research in Scientific American magazine noted, ever since the first set of federal guidelines appeared in 1980, Americans have been told to reduce their intake of saturated fat by cutting back on meat and dairy products and replacing them with carbohydrates. Americans have dutifully complied, and the rate of obesity has increased sharply. Meanwhile, the progress that the country has made against heart disease has largely come from medical breakthroughs such as statin drugs, which lower cholesterol, and more effective medications to control blood pressure.
Now 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 about 350,000 people published in the March issue of the American Journal of Clinical Nutrition, researchers at the Children's Hospital & Research Center Oakland 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 study out of Harvard this spring analyzed 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 digestible — like potatoes, white rice and white bread — increase the risk of diabetes and make people far more likely to contract cardiovascular disease than those who eat moderate amounts of meat and fewer carbs. Though federal guidelines now emphasize eating fiber-rich carbohydrates, which take longer to digest, the incessant message over the last 30 years to substitute carbs for meat may have done significant damage.
So far, it doesn't appear that the government will change its approach. 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 Assn. advised people to drastically reduce 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 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 group revised its restrictions on eggs to one a day, but it also recommended reducing consumption of other cholesterol-heavy foods to compensate. Similarly, the federal government's dietary guidelines still recommend an intake of no more than 300 milligrams of cholesterol daily, which makes egg consumption difficult. 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 not supported by scientific data."
More and more, the history of dietary guidelines brings to mind 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 wouldn't know that from government experts' increasing efforts to nudge us into their approved diets.