Eggs are one of the most nutritionally controversial foods, with some health experts swearing to their protein-packed incredible edibleness and others calling eggs as bad for the heart as smoking cigarettes. New evidence comes down on the against-eggs side, suggesting eggs do increase a person’s risk of developing heart problems—but not for the reasons most suspect.
The association between eggs and heart disease may have little to do with the longterm scapegoats, fat and cholesterol. Researchers suspect the risk actually has to do with lecithin, a compound found in eggs that reacts with bacteria in the human gut.
[In the} study, published this week in the New England Journal of Medicine, Stanley Hazen, of the Cleveland Clinic in Ohio, and colleagues, add more evidence to the growing pile that shows at least where heart disease is concerned, gut bacteria play an important role in the link between diet and health.
In a statement, Hazen—head of Preventive Cardiology at the Cleveland Clinic—said his team’s work is part of the charge to find “new pathways to attack heart disease.”
And thank goodness! For so long, the link between cholesterol and heart disease has opened more questions than provided answers. It was always tangential at best, but people clung to it in the absence of other, more plausible or better supported mechanisms.
Now we know that everything from omega-6 fatty acids to the digestive habits of gut probiotics are working for or against a healthy heart and blood vessels. It’s amazing, because it brings us so much closer to preventing and treating heart issues effectively. But it’s also scary, because the picture is complicated, and people don’t really like complicated nutrition messages.
Speaking of which … back to eggs. The egg-based nutrient, lecithin, is another compound that bacteria in the gut digest into artery-clogging metabolite TMAO. We know from previous studies that high blood levels of TMAO are associated with greater heart disease risk. In this latest clinical study, Hazen and team asked participants to eat two hard-boiled eggs, then measured their blood TMAO.
But when these same participants took a course of antibiotics (to wipe out their gut bacteria), their blood TMAO went down, and even eating eggs again did not raise it back up. This showed gut bacteria are essential for producing TMAO.
Only eat eggs when you’re on antibiotics? That seems to be one takeaway here, I guess.
In the second part of the study, the researchers tracked participants for three years. They found people with higher blood levels of TMAO were more likely to have a heart attack or stroke in this period, regardless of other risk factors and blood test results.
Earlier this month, the same team of researchers reported how L-carnitine—a compound found naturally in red meat and added to energy drinks—can contribute to heart disease and stroke. The clincher there was also gut bacteria, which digest L-carnitine to produce TMAO.