Do Eggs Lower Cholesterol? Or Do Lentils and Tofu!

At the Kahn Center, we strive to keep up to date on the latest science, often nutrition science. This week, headlines all over the world announced that a new study in Australia demonstrated that eggs lower cholesterol. Is this true?

 

It matters because cardiovascular disease (CVD) remains a leading cause of death. Although dietary cholesterol from eggs has been a focus of dietary guidelines, recent evidence suggests that saturated fat has a greater impact on LDL cholesterol. While a person eating 2 eggs a day may get 500-600 mg of cholesterol, Western diets often have 50 times that much saturated fat or more. So it is likely that saturated fat is the bigger player.

In this randomized, controlled, cross-over study, 61 adults (age 39 y)  with baseline LDL cholesterol <135μg/dL) were assigned to 3  diets for 5 wk each: high-cholesterol (600 mg/d), low-saturated fat (6%) including 2 eggs/d (EGG); low-cholesterol (300 mg/d), high-saturated fat (12%) without eggs (EGG-FREE); and a high-cholesterol (600 mg/d), high-saturated fat (12%) control diet (CON) including 1 egg/wk. Outcomes were assessed at the end of each diet phase.

Fifty-four participants completed ≥1 diet phase, and 48 completed all diet phases.

 

Compared with CON, EGG but not EGG-FREE reduced LDL cholesterol (CON 109 compared with EGG 104 μg/dL)).

 

Across all diets, saturated fat intake was positively correlated with LDL cholesterol whereas dietary cholesterol was not. 

The authors stated that "saturated fat, not dietary cholesterol, elevates LDL cholesterol. Compared with consuming a high-saturated fat diet with only 1 egg/wk, consuming 2 eggs daily as part of a low-saturated fat diet lowers LDL concentrations, which may reduce CVD risk".

 

What is wrong with this study? First, it was funded by the egg industry and some bias of the researchers is possible. "This work was funded by the Egg Nutrition Center, a division of the American Egg Board".

 

Second, the EGG group had a radical change in diet that requires reading the the methods section of the paper.that states "The EGG diet was low in saturated fat, achieved by including only lean meat and low-fat yogurt and cheese and incorporating plant-based proteins (for example, tofu and legumes)".

 

What was missing from the study was a group that ate low in saturated fat with only lean meat, or none, low fat-yogurt and cheese, or none, and incorporated plant-based proteins! Imagine how low their LDL-cholesterol would be. 

 

In conclusion, the word "misinformation" has been repeated over and over in the last 5 years, both in research and in social media. This study and the headlines were misleading and dozens of prior studies indicate that, for many, eggs can raise LDL-cholesterol. Yet, the foods rich in saturated fat, like meats, poultry, and dairy, remain the greater risk for CVD. It would wise to head a major review linking egg and cholesterol consumption with increased risk of all-cause mortality.