In an opinion column in today s New York Times, Drs. Dariush Mozaffarian of Tufts University and David S. Ludwig of Boston Children s Hospital describe the historical trajectory of official nutrition advice that has led to the demonization of dietary fat. Beginning with the 1980 Dietary Guidelines for Americans, an official goal has been to get Americans to reduce their total fat intake.
The authors note how this gave impetus to the low-fat products craze everything from skim milk to SnackWell s cookies were touted as being lower in fat and thus healthier. However, removing fat from such items encouraged food manufacturers to substitute with carbohydrates not necessarily the healthiest action.
But slowly, they say, the science has changed, and it has been reflected in later editions of the Dietary Guidelines:
2000: Limit total fat to 30 percent of calories
2005: Limit total fat to 20 to 35 percent of calories
2015: No upper limit on total fat
Now, the committee responsible for drafting the 2015 Guidelines is encouraging consumption according to healthful food-based diet patterns, say the authors. Their major concern is that the while the Guidelines are changing, federal guidance for items such as the Nutrition Facts panel still use the old 30 percent limit on total fat. And, they say, the FDA continues to regulate health claims based on total fat, no matter where that fat comes from.
They conclude that The limit on total fat is an outdated concept, an obstacle to sensible change that promotes harmful low-fat foods, undermines efforts to limit refined grains and added sugars, and discourages the food industry from developing products higher in healthy fats. Fortunately, the people behind the Dietary Guidelines understand that. Will the government, policy makers and the food industry take notice this time?
Dr. Ruth Kava, ACSH senior nutrition fellow commented, I certainly understand these authors frustration with the laggard action of the federal government. Hopefully the publication of the new Dietary Guidelines will spur some action on the part of policy makers and lead to advice that is more in line with scientific evidence. It is important to note, however, that whether it s 20, 30, or 40 percent of calories, dietary fat does provide more calories than either protein or carbohydrates, and it s important to figure in total calories when devising a healthy diet. That said, the saga of dietary fat advice is an excellent example of how science changes over time.