(CNN) – What was the first; the egg or the chicken? Perhaps that is not the most important question, but whether eggs are good or bad for your health.
Unfortunately, science also doesn’t seem to be able to establish a definitive answer to that.
Last year, a large Harvard University analysis of 215,000 people found that eating one egg per day was not associated with an increased risk of cardiovascular disease.
Now, a recent study of more than 500,000 people has found that eating even a daily serving of a whole egg, with its cholesterol-laden yellow yolk, increases the risk of dying from all causes, including cardiovascular disease and cancer.
In fact, the overall risk of death increased by 7% for every additional half a whole egg eaten per day, according to the study published Tuesday in PLOS Medicine.
Experts were skeptical.
“Despite many years of research, this question about egg consumption and health has not been answered, and there are multiple observational studies in recent decades that show conflicting results: some suggest that moderate egg intake is good, while others suggest it may be bad, ”said Riyaz Patel, a consultant cardiologist at University College London.
“This study, while well conducted, unfortunately only adds more noise to the discussion,” Patel said in a statement.
The study results are problematic because they only asked people once about their egg consumption, then followed them for many years without checking to see if their diet had changed, said Dr. Walter Willett, professor of epidemiology and nutrition at the School of Harvard Public Health TH Chan.
“They’re just getting a snapshot in time,” said Willett, who is also a professor of medicine at Harvard Medical School.
“The conclusions of this study are exaggerated,” said Ada Garcia, Senior Lecturer in Nutrition for Public Health at the University of Glasgow, Scotland, in a statement. “Blaming eggs alone for an increased risk of cardiovascular disease is a simplistic and reductionist approach to the concept of diet and disease prevention.”
What do eggs replace?
The poultry industry has long promoted that “eating eggs is awesome.” At just 75 calories, they say, one egg provides 7 grams of high-quality protein, 5 grams of fat, and 1.6 grams of saturated fat, plus iron, vitamins, minerals, and disease-fighting nutrients like lutein and zeaxanthin.
Eggs are affordable, making them an inexhaustible source of nutrition for families with limited food budgets. Many people who follow popular low-carb diets, such as keto, also rely heavily on eggs in their meal plans.
The problem, of course, is the cholesterol level in the yolk – the yellow part – of the eggs: a large egg yolk can produce about 185 milligrams of cholesterol.
Cholesterol is not the coconut. Produced by the liver, cholesterol is in every cell in the body and is used to make hormones, vitamin D, digestive compounds, and more. Sometimes a person’s body can make too much cholesterol, leading to waxy plaque buildup in blood vessels and later cardiovascular disease.
Cholesterol plays a role in our diet, but it’s more complicated than we used to think, said Willett, who has spent more than 40 years studying the effects of diet on the onset of major diseases.
Nutritional guidelines are used to recommend an upper limit of 300 milligrams of cholesterol per day. Current guidelines suggest eating as little as possible while keeping saturated fat to less than 10% of your daily calories.
The key, Willett said, is to look at the overall nutritional pros and cons of the food, as well as what the food is replacing in the diet.
Look at fish, for example. Fish contains cholesterol, but it also provides essential omega-3 fatty acids essential for optimal health.
And the saturated fats in butter, whole dairy, and fatty cuts of meat have a much more profound impact on raising blood LDL (low-density lipoprotein) levels than dietary sources of cholesterol such as eggs.
“If someone replaces eggs with donuts, other refined starches, and sugar or saturated fat, I’d rather have them eat eggs,” Willett said.
“But for someone who really wants to be in optimal health, putting an emphasis on plant-based protein sources like oatmeal and nuts would be a better way to go.”
However, some populations may want to monitor their egg consumption.
“Someone who is having a hard time using medications for their blood cholesterol levels would probably be better off keeping their eggs on the low side,” Willett said. “Eggs don’t have to be completely eliminated, but I think the old recommendation of no more than two eggs per week, for most people, is still a good recommendation.”
People with type 2 diabetes also need to be careful. The 2020 Harvard study found that higher egg intake by people with type 2 diabetes was associated with increased cardiovascular risk, a link that has been duplicated in previous studies.
What about the egg whites?
Can you safely replace egg yolks with egg whites? The new PLOS study found that replacing half a whole egg with an equivalent amount of egg whites or egg substitutes reduced the risk of death from cardiovascular disease by 3%.
“In my opinion, the recommendation made by the authors to replace whole eggs with egg whites is not supported by all the available evidence,” said Patel of University College London.
“Most studies haven’t looked at yolk-less eggs,” Willett said, “mainly because the consumption of egg whites is quite low in the general population. The lowest risk is replacing eggs with nuts and plant-based protein sources.
Patel added: ‘I don’t think this study changes the general advice, that for most people, eggs can be eaten in moderation as part of a balanced diet, unless they have been advised not to do so for a reason. specific medical or dietetic ”.
Editor’s note: This note was originally published in February 2021, but was updated on May 24, 2021.