CHICAGO — What will you have for brunch this Sunday? A pork belly and egg taco at Big Star? A lobster Benedict at Two Lights? Perhaps a classic omelette is more to your liking: What about the one at Etta's, with truffle goat cheese and maitake mushrooms? There's a simple green salad on the side. Healthy!
Actually, before you place that order, you might want to check in with Northwestern scientist Norrina Allen.
Allen, associate professor of preventive medicine at Northwestern University Feinberg School of Medicine, is one of the authors of a just-released study that analyzed data on nearly 30,000 subjects, following some of them for as long as 31 years, to gauge the impact that diet -- in particular, cholesterol consumption -- has on heart disease and other causes of death. As part of the study, "we examined the relationship between consumption of eggs and heart disease," she says, "and found that increased egg consumption is directly related to heart disease and mortality."
That finding sounds deceptively simple -- cholesterol has been a bad word for a long time, after all -- until you consider that, for years, public health wisdom around eating eggs has shifted so often, it makes U.S. foreign policy on Iran look stable by comparison.
"There have been really contradictory findings in the (scientific) literature and in the press," says Allen. "There are studies that have shown benefits of eggs, studies that have shown no effect, and studies that show a negative effect. It's confusing for people."
Official guidelines from the American Heart Association and the USDA have shifted dramatically over the years: In 1968, the AHA recommended a cholesterol intake of no more than 300 milligrams per day, and no more than three to four egg yolks (which contain all of an egg's cholesterol) per week. But in 2013, the group lifted its numerical limit on dietary cholesterol, citing a lack of solid scientific research documenting a link between cholesterol we eat and the bad cholesterol that shows up in our blood, resulting in clogged arteries and heart disease. In 2015, USDA dietary guidelines for Americans followed suit, eliminating the cholesterol intake ceiling.
To add to the ambient noise around eggs, consumers are bombarded with both anti-egg messages and constant boosterism from the American Egg Board, an arm of the USDA that churns out egg marketing (and a lot of egg-related puns: Eggceptional! Eggcellent!).
Eggs, to mix metaphors, are a hot potato. "I'm a little nervous about that part," admits Allen, who is aware that her new study is dropping a bit of a bomb onto your cholesterol-heavy brunch table.
The Northwestern study shifts blame for cardiovascular disease back to dietary cholesterol consumption, at a time when prevailing scientific wisdom is that the cholesterol we eat has little to no impact on our blood cholesterol. Instead, studies have focused on the role of saturated fat as the real dietary villain in heart disease. But Allen and her co-authors found that eating 300 milligrams of cholesterol per day was associated with a 17 percent higher risk of cardiovascular disease, that eating three to four eggs per week was associated with a 6 percent higher risk of cardiovascular disease -- and that cholesterol was the driving factor, even when saturated and other dietary fats were considered.
"One strength of our study," she says, "is that we were able to take into account a lot of the other details of diet and diet quality. And another is that this is a real picture of an American experience."
Other studies, in particular a much-cited Chinese study that showed a beneficial effect from egg consumption, have been questioned when applied to the U.S. population. Chinese research subjects, obviously, were not eating the typical American diet.
And, as you've probably guessed, it's that typical diet that's the real problem.
Got a carton of eggs in the fridge? Bet you've also got a pound of bacon, some butter, a hunk of cheese ... all of which add to the overall cholesterol in your diet. "It's not so much the egg, but what we eat it with" says Jo Ann Carson, a professor of clinical nutrition at the University of Texas Southwest medical center, and past chair of the American Heart Association nutrition committee. "Bacon has become so popular, in my perception, that we're putting bacon on everything. So when you think about how we typically eat eggs, with the bacon, sausage, biscuits, that is not what we're encouraging."
Though current U.S. dietary guidelines -- which may shift on Sunday when the AHA is slated to release new ones -- do not set a numerical cap on cholesterol consumption, the Northwestern study shows an uptick in cardiovascular disease even at the old "acceptable" number of 300 milligrams per day. One egg yolk contains nearly 200 milligrams of cholesterol, which makes sticking to a 300-milligram limit nearly impossible "if you eat an egg every day," says Allen. Especially if you're doing things like cooking that egg in a little bit of butter, or adding sausage on the side, since processed meats are the other cholesterol-laden treat that's common in American diets.
Allen says that's an indicator that American diets might need a general overhaul in terms of cholesterol consumption. Still, if you're tired of trying to sort through the details and just want someone to tell you whether or not you can eat eggs, Allen and other experts are here for you. And the answer is ... a qualified yes.
"People go 'What do we really know, who can we trust, why do scientists keep changing their minds?'" says Dr. John La Puma, a California nutritional consultant, author and trained chef who has focused on helping clients lower cholesterol through diet. "The answer is that we are trying to simplify something that is actually pretty complex." Factors for cardiovascular disease, he says, are little understood and wide-ranging, encompassing everything from environment and stress to genetics. LaPuma sidesteps the whole debate by offering patients lists of foods that help lower cholesterol, including tree nuts, flax meal, green tea and steel cut oats.
Though the Northwestern study shows a clear link between cholesterol in our diets and cardiac disease, Allen says, "more research is needed to understand exactly how. We're moving forward, I think, but we haven't answered the question yet."
That's why you'll find eggs on the breakfast table at Allen's house, and La Puma's and Carson's. "Like a lot of things in our diet, there are good sides and bad sides to eggs," Allen says, noting that eggs are nutrient-dense and contain beneficial things such as lutein and choline.
The AHA focuses on "an overall healthy eating pattern," says Carson, "which can include eggs as a source of protein, alongside a lot of fruits and vegetables and whole grains."
No need for dramatic sacrifices, she says. "We don't need to be overly concerned like, 'I'm never going to eat an egg.'"
But this Sunday at the brunch table ... maybe just get the egg whites.