Egg phospholipids, heart health and TMAO formation
What it found
Egg phospholipids may help cholesterol handling and blood vessel health in some ways, but eating eggs also raises a gut-made compound called TMAO in people.
Whether the benefits outweigh any risk is still unknown.
What they found
Studies in people
HDL and cholesterol transport
In people, eating egg yolks increased HDL cholesterol and HDL particle size, and improved markers of reverse cholesterol transport such as LCAT activity and cholesterol efflux capacity. These changes may reflect a greater capacity for removing cholesterol from arteries.
Inflammation
In overweight men and adults with metabolic syndrome, eating three eggs a day for 12 weeks reduced some markers of inflammation, while yolk-free egg substitute did not. Choline, which eggs contain, has also been linked to lower inflammation markers in healthy adults.
TMAO formation
In people, eating egg yolks raised blood levels of TMAO, a compound made by gut bacteria, in a dose-dependent way. TMAO levels peaked 6 to 8 hours after eating, and there were large differences between individuals.
Animal and lab studies
Cholesterol absorption
In animal and cell studies, egg phospholipids such as phosphatidylcholine and sphingomyelin reduced the absorption of cholesterol and fats. Egg phosphatidylcholine was better at this than soy phosphatidylcholine, and hydrogenated egg phosphatidylcholine had a stronger effect than natural egg phosphatidylcholine.
Liver fat metabolism
In rats and mice, egg phospholipids changed liver fat metabolism, lowering liver and blood lipids in some studies. Short-term feeding of egg phosphatidylcholine to mice did not change liver lipids, but a hydrogenated form did.
Studies in people and animals
TMAO and heart risk
In mice, diets rich in choline or TMAO increased artery lesions, and this effect depended on gut bacteria. In people, higher TMAO levels have been linked to higher risk of heart disease and death, but the effect of long-term egg intake on TMAO is not known.
What the authors conclude
“It will be critical determine if the perceived benefits of egg PL intake on CVD risk markers outweigh the risk of potential TMAO formation”
Also in their conclusions
- They say that based on laboratory studies, egg phosphatidylcholine and sphingomyelin appear to regulate lipid absorption, liver lipid metabolism and inflammation.
- They note that in clinical studies, egg phospholipid intake is linked to beneficial changes in markers of HDL function.
- They call for more research on TMAO responses to long-term egg intake and in different groups, such as people with diabetes, to see if the benefits outweigh any risk.
How it was done
Eggs are a major source of phospholipids in the Western diet, and these fats may affect inflammation, cholesterol metabolism and HDL function. The authors wanted to summarise recent laboratory, clinical and population research on egg phospholipid intake and heart disease risk.
The authors reviewed laboratory studies in cells and animals, clinical studies in people, and large population studies that looked at egg phospholipid intake and heart disease risk. They also examined studies measuring TMAO levels after people ate eggs.
What it can’t tell you
- The review cannot show whether eating eggs causes heart disease or protects against it, because it combines different types of studies.
- The long-term effects of egg intake on TMAO levels in people have not been studied yet.
- It is not known whether the TMAO rise from eggs is large enough to affect heart disease risk.
Who paid
- Authors work at
- University of Connecticut, USA
The paper
- Title
- Egg phospholipids and cardiovascular health
- Type
- ReviewThe authors read earlier studies and describe what they found. It isn’t a new study.
- Evidence
- Studies in people · animals · lab
- Summarised from
- Full text
- Cite
- Blesso CN (2015). Egg phospholipids and cardiovascular health. Nutrients. doi:10.3390/nu7042731Free full textPubMed 25871489DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error