Do Eggs Harm Your Gut Microbiota? Here's the Scientific Verdict

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The narrative surrounding eggs has been akin to a pendulum, swinging between the realms of healthy and harmful over the years. While at one time, they were considered cholesterol-laden heart hazards, they have also been praised as nutrient-packed superfoods.

Now, as the scientific inquiry zooms into the gut microbiome, eggs find themselves under scrutiny once again: How do eggs interact with our gut microbiome and what ripple effects does this interaction cast on our health?

TMAO and Its Implications

First, it's essential to understand some biochemistry about trimethylamine-n-oxide (TMAO). TMAO prevents the expulsion of cholesterol from our arteries, thus amping up the clot-forming activities of platelets and inflammatory responses.

As a result, TMAO is implicated in serious health conditions like heart attacks, strokes, and kidney disease. So we want to steer clear of elevated TMAO levels.

The plot thickens as we learn that TMAO is not an uninvited guest; it’s actually produced in our gut, courtesy of a biochemical metabolism of choline and carnitine. As we devour foods rich in these compounds, our gut microbiome converts them into TMA, which eventually turns into TMAO.

Now, here’s where eggs strut onto the scene.

Eggs and the Choline Connection

Eggs are choline-rich stars, so much so that a quartet of eggs fulfills well beyond our daily choline quota. The narrative thus far might paint a grim picture, suggesting that indulging in eggs could set the stage for cardiovascular diseases.

But before we banish eggs to the dietary blacklist, a closer inspection of our anatomy reveals a different story.

The choline tale has a dichotomy—it is bound to a fat molecule (i.e., a phospholipid) or found in salt avatar as choline bitartrate. While supplements and fortified foods exhibit the latter, eggs proudly flaunt the former.

In other words, choline in eggs is bound to a phospholipid, which allows it to be quickly absorbed in our small intestines, thus preventing our gut microbes in the large intestines from turning it into TMAO. Therefore, despite their choline richness, eggs don’t quite play the villain in the TMAO narrative.

The Sulfur Story: Potential Gut Implications

Yet, before we give eggs a clean chit, there’s another chapter to this saga. The protein found in eggs contains sulfur, which upon digestion, can result in hydrogen sulfide gas production, particularly in the presence of certain gut microbes. This gas has the potential to trigger gut inflammation at high levels.

But not everyone's gut microbiome has the bacteria that can produce hydrogen sulfide gas. Examples of hydrogen sulfide-producing gut bacteria are Deltaproteobacteria, Thermodesulfovibrio, Desulfotomaculum, and Archaeoglobus

For those housing a colony of sulfide-producing bacteria, a balancing act with lactic acid-fermenting species like Lactobacillus could be beneficial. Additionally, toning down the intake of sulfur-rich foods like eggs might be a wise strategy.

In the final analysis, while the choline in eggs doesn’t create TMAO in our gut, the sulfur content could stir the pot for some, particularly those with a predisposition to gut inflammation. Yet, with a balanced approach, eggs can continue to be enjoyed as a nutritious protein and fat component of our diet.