Uh-oh – Better Stop Eating Eggs Again – or, Fake News!
Headline in the March 15, 2019 New York Times: “Are Eggs Bad for Your Heart Health? Maybe A new analysis found that for each additional 300 milligrams a day of cholesterol in the diet — and the more eggs you ate — the greater the risk for cardiovascular disease.”
Headline in the March 15, 2019 Wall Street Journal: “Study Links Eggs to Higher Cholesterol and Risk of Heart Disease Eating 300 milligrams of dietary cholesterol a day—or less than that of two egg yolks—was associated with a 17% higher risk of cardiovascular disease”
I began to see other versions of this story in other media, always with dramatic headlines or click-bait enticements. My email was filling up with “Hey Rick, I thought you said eggs were back in the good column! What’s up with this?”
The articles were referring to a paper to be published later that week in the Journal of the American Medical Association (JAMA) titled “Associations of Dietary Cholesterol or Egg Consumption With Incident Cardiovascular Disease and Mortality.” While the benefits and risks of eating eggs might still be called controversial, in my humble opinion it is settled: don’t worry – eat all the eggs you want.
Let’s briefly pick this study apart (with thanks to Zoë Harcombe Ph.D.) Here are a few of the problems:
The paper is a “meta-analysis” that looks at six underlying studies of egg and dietary cholesterol consumption and their association with cardiovascular disease (CVD). These studies are not Randomized Controlled Trials, or RCTs, which attempt to find causation. They are epidemiological studies, which can establish correlations that might then lead to RCT studies. None of the underlying studies here attempted to show causation, and the study authors don’t claim that eating eggs causes a higher risk of CVD or earlier death. The very first word in the headline is “association” – that’s not causality, but inferring causality sells more newspapers.
Data collection in nutrition studies is extremely difficult; these underlying studies have not found a way around that, and so rely on faulty data, perhaps extremely so. For instance, how do the studies collect data on the number of eggs eaten over the many years the studies ran? Participants were asked to fill out food surveys about what they ate, some just annually, some over even longer periods. Do you remember what you had for breakfast 3 days ago, let alone 300 days ago? Do you know how many eggs you had last year?
The data rely on “mixed ingredients” foods that may contain eggs, not just actual eggs, but the articles fail to point this out. Mixed ingredient foods include cake, doughnuts, ice cream, etc. Since this JAMA paper only purports to show association, not causation, how can we know that it wasn’t the highly processed flour in those doughnuts, or the vegetable oil the eggs and home fries were fried in, or the sugar in the ice cream that “caused” the increase in relative risk?
We encounter another incidence of that famous saying attributed by Mark Twain to the British prime minister Benjamin Disraeli: "There are three kinds of lies: lies, damned lies, and statistics." That Wall Street Journal headline would more properly read “…17% relative risk…” The largest study in the group of six began in 1989 and comes from a project called “The Atherosclerosis Risk in Communities Study (ARIC). It reported a 17% increase in relative risk of cardiovascular disease incidents in a study population of 255,000 that suffered 16 deaths per 1,000 person/years. A 17% increase raises that to 17 deaths per 1,000 person/years. In my humble opinion, that very slight increase is not worth the sensationalism, especially when we know that this only purportedly shows a correlation, not causation.
Newspapers get away with this drama because of conventional wisdom that is actually highly disputed. First, it has been shown in many studies that that there is very little or no relationship between dietary cholesterol and blood cholesterol. For the most of us, eating eggs has no effect on those cholesterol numbers you get from your good doctor. Second, there are many studies that show no link between cholesterol in your blood and CVD – some even show a healthy correlation.
The JAMA paper’s authors have many disturbing conflicts of interest, having worked for or had their research funded by pharma companies such as Astra Zeneca, Merck, GlaxoSmithKline, Novartis, and others – a who’s who of corporate interests eager to keep that flow of statins going. While those affiliations and the money behind them do not by themselves impugn their integrity, it is worth mentioning in the newspaper articles, don’t you think?
So pay no attention to these recent scare tactics from the sensationalists. For almost all of us, two to three eggs per day would be a step up in nutrition, especially compared to the standard American diet.
One last note: if you can, get “pastured” eggs. That’s the top of the hierarchy of terms like “cage-free”, “organic”, “hormone-free”, etc. That’s all good vs. conventional, factory-farmed eggs. Why pastured? The ratio of pro-inflammatory omega-6 fatty acids to omega-3 acids is far better eggs from hens kept cooped up, fed only grains, etc. Hens should be free outdoors, running around the yard, picking at bugs and grass and whatever else delights them. They’ll process it all for us.
I’m very lucky to live where friends with pastured hens bring them for house presents, and local farmers leave them in coolers by the side of the road with honor-system cash boxes. If you’re not that lucky, check out the Eat Wild site to find pastured eggs and other goodies in your area.
For a good, full debunking of that recent study, read Zoë Harcombe, Ph.D. For a great short article on why you should not fear eggs or cholesterol, read Chris Kresser’s recent blog “Three Eggs a Day Keep the Doctor Away!”
P.S. Yesterday I had two eggs on a bed of kimchi for breakfast. What about dinner? Eggs scrambled with some potato starch and cheese. Yummy, and healthy!