What's Wrong with Eggs? | Nutrition Mythbusters
Balanced is excited to bring to you our Nutrition Mythbusters series in which we debunk eight major myths about the links between diet and health! We believe that accurate, evidence-based nutrition information should be accessible to everyone. That’s why we created this educational series dispelling some of the most common and persistent misconceptions regarding healthy, balanced eating and diet-related disease. You can find the video episode of today's blog on our YouTube channel.
Back in January 2019, we published a blog post refuting some of the claims made in an article touting the supposed wholesomeness of eggs. Now, in February 2021, I’m sorry to say that regularly consuming eggs is still risky for health.
Nonetheless, a Google search with the keywords “eggs healthy” yields a wealth of results—a couple of which are from reputable sources like the American Heart Association and Harvard Health—in support of consuming eggs roughly three to seven times a week for “healthy” individuals. (Already, they’re speaking of a minority of American adults, and it’s unclear how “healthy” is defined.)
Interestingly, many of these articles—the ones not written by egg industry-employed dietitians, anyway—take a rather timid, equivocal stance on eggs, something akin to, “Well, we have this conflicting data about eggs and heart disease, but it’s probably fine to eat maybe an egg a day, I guess?” Basically, their words don’t inspire a lot of confidence.
It’s true that the data are mixed when it comes to eggs and cardiovascular disease, but as I described in our 2019 blog post, much of the science has been compromised by the egg industry’s strategic meddling, along with major flaws and limitations in study design, analysis, and interpretation.
Even still, many studies do show poorer health outcomes for those consuming more eggs, including a 2019 study published in JAMA which found that consuming more than two to three eggs per week conferred a small but significant increased risk for heart disease and death by any cause. Harvard professor Dr. Teresa Fung commented on the study for the Harvard Heart Letter urging the public to set the limit at two eggs per week to play it safe.
Moreover, roughly 30% of people are “super-reactors” to dietary cholesterol due to their genetics; for these individuals in particular, consuming cholesterol-rich eggs regularly may be extra risky for heart health. But it’s more than the negative cardiovascular impacts of egg consumption that we should be worried about.
You may recall from our Mythbusters installment on saturated fat and cholesterol that the processes of cooking and metabolism oxidize cholesterol into more dangerous forms known as cholesterol oxidation products, or COPs. COPs are involved in both initiation and progression of chronic diseases, such as atherosclerosis, neurodegenerative disease, kidney failure, and diabetes.
Indeed, in a Harvard study investigating the link between egg consumption and diabetes, men and women who ate just one egg per day raised their risk of developing type 2 diabetes 58% and 77%, respectively, relative to those consuming less than an egg per week. Similarly, women eating at least one egg daily before and during pregnancy had roughly double the risk of developing gestational diabetes, which can severely harm the health of both mother and baby.
There’s also the link between egg and cholesterol intake and cancer. The science is a bit more complex here because there are multiple mechanisms by which egg consumption could mediate the promotion of tumors. For example, blood and urine levels of TMAO generated from the choline and carnitine in eggs (described in our original 2019 blog post) are closely correlated with, and even predict development of, cancers of the gastrointestinal tract. More research needs to be done in this area, but cholesterol intake in general is associated with a wide range of cancers, including stomach, pancreas, colon, rectum, kidney, bladder, breast, and lung cancers and non-Hodgkin’s lymphoma.
Nevertheless, eggs can be included in an otherwise healthy diet, just not on the order of an egg per day as some experts have arbitrarily opined. I tend to agree with Dr. Fung—two eggs maximum per week, and preferably fewer than that.