Can eggs be eaten? Two studies involving more than 500,000 people in China and the United States have opposite conclusions

A recent study seems to support the idea that some people only eat the egg whites and discard the yolks.

A study of 500,000 people in the United States: Eating egg yolks is not recommended

Researchers from Zhejiang University analyzed data from a 16-year follow-up of 520,000 Americans and found that if residents eat more eggs, their risks of all-cause mortality, cardiovascular mortality, and cancer mortality will increase, mainly due to increased cholesterol intake.

Eating eggs without egg yolks or other egg white substitutes can help reduce the risk of death and improve cardiovascular health.

The authors say that current recommendations in the U.S. Dietary Guidelines regarding egg and cholesterol intake may lead to increased cholesterol intake, which will increase residents' risk of premature death.

Physicians and policymakers should emphasize dietary cholesterol intake and recommend not eating egg yolks or other proteins.

The researchers said that this study is the largest study to date, enrolling 520,000 people, correcting for several major potential confounding factors and following up for 16 years, with nearly 130,000 deaths.

The average age of residents in the study was about 62 years old. The average body mass index was about 27. The daily whole egg intake was 8 g/2,000 kcal, and the cholesterol was 208 mg/2,000 kcal.

At baseline, residents who ate more eggs had a higher body mass index, lower household income and education, less physical activity, a higher rate of smoking, higher cholesterol levels, and were less likely to take aspirin. They also had lower healthful dietary indices, such as higher red meat intake and less fruit and dairy products.

The study found that for every additional 300 mg of cholesterol consumed per day, the risk of all-cause mortality increased by 195%, cardiovascular mortality increased by 16%, and the risk of cancer death increased by 24%.

The authors say that in Western countries, people who eat eggs tend to have unhealthy lifestyles, such as smoking, lack of physical exercise and an unhealthy diet, while also eating more saturated fat and animal protein.

I also found that whether you fry the eggs or boil them, the result is the same.

It was also found that if only egg whites were consumed without the yolks, or if other proteins (dairy products, nuts and beans) were used instead, the mortality rate decreased.

Researchers believe that meat with lower cholesterol content is healthier than eggs, and there is a positive correlation between dietary cholesterol and all-cause and cardiovascular mortality.

Eating 200 mg less cholesterol per day can reduce total blood cholesterol levels by 0.13 mmol/L and low-density lipoprotein cholesterol (LDL-C) levels by 0.10 mmol/L.

The study observed that the association was slightly weakened after correcting for blood cholesterol levels, suggesting that blood cholesterol may at least partially account for the link between eggs and disease.

The authors also note that the results of this study may not be generalizable to countries outside the United States due to differences in nutrition and dietary patterns and the prevalence of chronic diseases.

A study of 500,000 people in China found that eating eggs is good for your health

Should we eat eggs? Don’t panic.

A 2018 Chinese study of over 500,000 people found that people who ate eggs every day had an 11% lower risk of cardiovascular events and an 18% lower risk of death from cardiovascular events than those who basically did not eat eggs.

In this study, the average age of Chinese residents was about 50 years old, and the average body mass index was 23.5.

Compared with Chinese residents who never or rarely eat eggs, those who eat eggs every day have higher education levels and family incomes, eat more fresh fruits and protein (meat, poultry, eggs and dairy products), and take multivitamin supplements.

The authors of the Chinese population analysis said that although dietary cholesterol increased blood levels of total cholesterol and LDL, it also increased high-density lipoprotein (HDL) and the LDL/HDL ratio.

Eggs can increase satiety and also contain phospholipids and lutein, which have anti-oxidation, anti-inflammatory and anti-atherosclerotic effects.

Don't mess with an egg

Dietary research is the most maddening. One moment they say you can eat this, and the next moment they say you can’t eat this.

In fact, observational studies are subject to potential confounding factors. Despite the best efforts to correct for them, there may still be confounding caused by other unmeasured or unknown factors.

For example, in the Chinese study, the people who ate eggs were higher-income or better educated, took supplements, and seemed to be more health-conscious, and the results showed that less than one egg a day was good.

In a study of Americans, those who ate more eggs were fatter, had lower family income and education, less physical activity, a higher smoking rate, and higher cholesterol levels. They seemed to be a less healthy group of people, and the conclusion was that eating eggs is bad for you.

Therefore, observational studies cannot conclude that there is a cause-and-effect relationship between eggs and disease, only that there is an association.

In these observational studies, the association is more likely due to other concomitant lifestyle or risk factors in residents who eat eggs.

In fact, many factors, such as dietary patterns, physical activity and genetic factors, have a greater impact on cardiovascular disease and health.

What should we do? Based on the current evidence, or based on China's current recommendations.

China's Guidelines for Healthy Lifestyle to Prevent Cardiovascular and Metabolic Diseases recommend that it is best for adults to eat 3 to 6 eggs per week. It also emphasizes the need to limit daily cholesterol intake.

source:

[1] Egg and cholesterol consumption and mortality from cardiovascular and different causes in the United States: A population-based cohort study. PLoS Med, February 9, 2021

[2] Chinese Guidelines for Healthy Lifestyle to Prevent Cardiometabolic Diseases. Chinese Journal of Circulation, 2020, 35: 209-230. DOI: 10.3969/j.issn.1000-3614.2020.03.001【Download full text】

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