Up until recently US government policy for the past 40 years has maintained that dietary cholesterol may cause heart disease.
This has now been reversed with the Dietary Guidelines Advisory Committee deciding to ditch their warning that claimed there was a link.
Even five years ago, the committee was still promoting the warning first popularized by the American Heart Association in 1961. But the new position has been a long time coming.
“There’s been a shift of thinking,” said Walter Willett, chair of the nutrition department at the Harvard School of Public Health. He called the committee’s decision to drop the cholesterol warning a “reasonable move.”
New scientific consensus
The Dietary Guidelines Advisory Committee provides science-based recommendations to the federal government, in the form of a publication called “Dietary Guidelines.” The government uses that publication to make decisions about everything including dietary advice (such as the food pyramid), school lunch content and food labeling policy.
In its new recommendations, the committee has embraced the emerging scientific consensus that consuming cholesterol in foods such as eggs, shrimp or lobster does not significantly increase blood levels of cholesterol in healthy adults, and does not increase the risk of heart disease. That’s because the body actually produces its own cholesterol, in levels much higher than those that can realistically come from food.
The new consensus warns instead against a diet too high in saturated fat, the nutrient the body uses to make cholesterol. High levels of LDL (“bad”) cholesterol in the blood are still considered a risk factor for heart disease.
The change in policy is a classic example of the way that nutrition guidelines continue to change as scientific understanding evolves — often greatly confusing consumers along the way. Although the cholesterol debate may soon be settled, nutrition researchers continue to debate the relative merits and risks of other foods and nutrients such as saturated fat, salt, red meat, sugar and omega-3s.
“Almost every single nutrient imaginable has peer reviewed publications associating it with almost any outcome,” nutrition science critic and Stanford University professor John P.A. Ioannidis wrote. “In this literature of epidemic proportions, how many results are correct?”
Based on faulty science
The idea that cholesterol causes heart disease is pervasive in U.S. culture. Indeed, the adoption of cholesterol warnings directly led to a drop in per capita egg consumption of about 30 percent. But the scientific case for such a warning was never strong.
The experiment that started it all was conducted in 1913 by Niokolai Anitschkov and colleagues at the Czar’s Military Medicine Institute in St. Petersburg. The researchers fed rabbits cholesterol and saw that the animals developed cardiovascular disease.
Later research showed that rabbits are one of the few animals on the planet that react to dietary cholesterol in this way. But the idea had seized hold of the scientific establishment, and further studies at first seemed to support a link between cholesterol and heart disease.
But there were always those who considered the evidence against dietary cholesterol to be weak. In 2013, a task force convened by the American College of Cardiology and the American Heart Association concluded that there was insufficient evidence to support a warning against the nutrient. Many of the studies done were too broad in scope to be useful, it said.
“Looking back at the literature, we just couldn’t see the kind of science that would support dietary restrictions,” said task-force co-chair Robert Eckel, of the University of Colorado.
Indeed, all other countries on Earth have long since stopped warning against dietary cholesterol.
“The U.S. is the last country in the world to set a specific limit on dietary cholesterol,” said nutrition scientist David Klurfeld, of the U.S. Department of Agriculture. “Some of it is scientific inertia.”