The advisory panel for nutrition guidelines in the US might drop its warning about eating cholesterol-heavy food, something Americans have been warned about for decades.
The US' Dietary Guidelines Advisory Committee has long warned about keeping cholesterol levels at or below 300 mg a day to prevent heart problems — that's about an egg and a half. But because of a new understanding of current evidence, that advice could change: a preliminary report from the group, issued in December, would take cholesterol off the list of nutrients of concern.
The advice is not final, although experts on the issue say they generally expect the government to follow the initial recommendations. Nutritional advice on cholesterol "has already shifted" in the same direction, says Janet de Jesus, a nutritionist at the National Heart, Lung, and Blood Institute who has worked on the American Heart Association and American College of Cardiology panel that makes similar cholesterol recommendations.
Here's what you need to know about what cholesterol is, why the nutrition advice could be changing, and how it could change what you should eat.
How cholesterol works
Cholesterol is a fatty substance found in all the cells of the human body. It's necessary to make hormones, vitamin D, and other substances used in digestion. Our bodies naturally produce all the cholesterol we need, but we sometimes eat cholesterol in the foods, leaving us with more than we require.
There are two different types of cholesterol we hear about, and they're made distinct by the kinds of containers they're in: low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
LDLis what's often referred to as "bad cholesterol" because at high levels it can lead to a buildup of plaque in arteries, which can cause heart attacks, strokes, and other problems.
HDL often gets dubbed the "good cholesterol" because it helps remove LDL from the body by bringing it to the liver, which breaks it down.
Cholesterol warnings have been the same since the '60s
In the 1960s, the American Heart Association issued the first warning about watching how much cholesterol you eat.
The AHA's original report advised lowering cholesterol intake, citing an early study that found that rabbits fed cholesterol and other fats developed blockages in their arteries. It also cited similar studies that led scientists to believe that changing people's diets could help reduce cholesterol in their blood.
Also, studies had found that Americans consumed proportionally more fats in their diet than many people in Asia, Africa, and Latin America. And some reports indicated that there were fewer heart attacks in those places, too.
The concern about cholesterol was so great that people started avoiding eggs, which each have about 220 mg of cholesterol — almost 75 percent of the daily limit. The egg got such a bad reputation that in 1977, the American Egg Board started the Incredible Egg promotional campaign:
Some people even attempted to create low-cholesterol eggs, but they didn't take off.
The 1960s cholesterol guidelines have pretty much stuck for the last 50 years. In the US Dietary Guidelines Advisory Committee's most recent report in 2010, it listed cholesterol as a nutrient people should reduce in their diet and recommended less than 300 mg per day for the general population and less than 200 mg per day for people who are obese.
Why scientists have been wary of cholesterol
Cholesterol levels in the blood are determined partly by genetics and partly by environmental factors like diet.
If bad cholesterol gets too high, it can harm people's health. Cholesterol can help build up plaque inside of arteries and narrow them, causing coronary heart disease, heart attacks, and strokes.
For example, people with high blood cholesterol — about one-third of American adults — are about twice as likely to develop heart disease as those with low levels.
Why the advice is changing
The Dietary Guidelines Advisory Committee is a group of researchers that meets every five years to counsel the federal government on nutrition guidelines. Its preliminary report in December took cholesterol off the list of nutrients of concern.
Why the change? There has been a trend of changing attitudes toward cholesterol as researchers have gathered new evidence and reevaluated old data. The change echoes the thought of many nutrition experts, who have come to think that, in most cases, a moderate diet won't impact blood levels of bad cholesterol enough to harm health.
The likely change in guideline recommendations points to a shift toward monitoring substances such as trans and saturated fats instead of cholesterol, says de Jesus.
And the data behind the cholesterol warnings doesn't quite stack up. "Some of the evidence that may have looked significant 40 years ago, or even 10 years ago, doesn't anymore," says de Jesus.
In recent years, her department has reviewed the information on cholesterol. The institute's most recent cholesterol report, from 2004, focused on issues with too much consumption of saturated and trans fats, which significantly lower good cholesterol, raise bad cholesterol, and increase the risk of developing heart problems and type 2 diabetes.
So what should you eat?
What the likely change in guideline recommendations really affects are foods that are high in cholesterol, but low in other problematic fats, like eggs, shellfish, and shrimp.
(But foods like whole milk, butter, cheese, and some meats should still be consumed in moderation. "A lot of foods that have cholesterol are also high in saturated fat," says de Jesus.)
The new guideline recommendations could also impact lunches in public schools. "When you recommend that you restrict this or that, that matters when a meal is being prepared under some regulations," says Dr. Seth Martin, cardiovascular researcher at Johns Hopkins University. So more egg salad, perhaps?
But overall, he says that the new recommendations would fall in line with how many physicians already counsel their patients about diet. Rather than tell them what's bad to eat, he focuses on telling them what's good to eat.
"To me, the implications of this, it doesn’t change my practice and how I approach my counseling of patients," he says. If you don't have high cholesterol, you should be OK eating a generally healthy diet and getting enough fruits and vegetables. People should still get their cholesterol tested every five years to see how much "bad" cholesterol is in their blood. And if you have high cholesterol, you should still watch how much cholesterol you eat.
Update: This story has been updated to include quotes from sources who believe it is likely that the federal government will adopt the preliminary cholesterol report recommendations.
WATCH: Centers for Disease Control director Tom Frieden on simple ways to live longer, healthier lives - Vox Conversations