Does eating eggs increase my risk of heart disease?
Research has found a link between eating eggs and an increased risk of heart disease and death. But do you need to worry about eating eggs? We look behind the headlines.
People who eat more eggs have a higher risk of heart disease and death, a new study has found.
The researchers believe this is due to the cholesterol in eggs. This contradicts current thinking that the cholesterol in foods isn’t a cause for concern, as eating saturated fat (the kind found in butter, cheese and meat) does more to your levels of cholesterol. Although people with heart disease used to be warned against eating eggs, this hasn’t been the case for about 20 years, and UK guidelines on healthy eating do not recommend a limit on the amount of cholesterol we should be consuming.
Researchers have published results from a large study linking egg consumption to an increased risk of heart disease and death. The researchers at the Northwestern University in Chicago collected data from six US studies, involving 29,615 people in total. These studies were observational, meaning that they collected information about people’s diets and monitored their health outcomes, rather than asking people to follow a certain diet.
At the start of the studies, people were asked to provide detailed information about their diets, including how many eggs they eat per day. In the US where the study was carried out, one large egg contains 186 milligrams of dietary cholesterol (a large egg in the UK is bigger, containing 235 mg). Participants also provided other information about their lifestyles, such as how much exercise they do. Their health was then monitored for an average of 17.5 years.
The study found that for each half an egg consumed per day, people had a 6 per cent higher risk of developing cardiovascular disease...over 17.5 years
The average American consumes approximately 295 mg of cholesterol per day, including 3 to 4 eggs per week. The study found that for each half an egg consumed per day, people had a 6 per cent higher risk of developing cardiovascular disease, and an 8 per cent higher risk of death over 17.5 years.
To find out whether cholesterol in the eggs could explain this association, the researchers then looked at people’s cholesterol intake separately. For each additional 300 mg of cholesterol consumed per day (from eggs, meat and high-fat dairy products), participants had a 17 per cent higher risk of developing cardiovascular disease, and an 18 per cent higher risk of death.
When the researchers then compared the risks associated with egg consumption and cholesterol consumption, they found that the cholesterol content of eggs explained the increase in the risks observed with egg consumption. This suggests that the cholesterol in eggs is likely to be driving the increased risks observed with consuming eggs.
UK nutrition guidelines recommend eating eggs as part of a healthy balanced diet, as they are a good source of protein and vitamins. The researchers suggested that their findings should be considered in future updates of dietary guidelines.
The BHF view
Victoria Taylor, Senior Dietitian at the British Heart Foundation, said:
“There has been much debate about the role of eggs in relation to heart and circulatory disease. This study suggests that people who ate more eggs were at a greater risk of heart disease because of the cholesterol that’s in them.
"However, this type of study can only show an association rather than cause and effect and more research is needed for us to understand the reasons behind this association.
Eating healthily is all about balance.
Victoria Taylor, Senior Dietitian at the British Heart Foundation
"Eating healthily is all about balance. If you’re eating too much of one thing it leaves less room in the diet for other foods that may have more health benefit.
"Eggs are a nutritious food, while this study focuses on the amount that we’re eating it’s still important to pay attention to how the eggs are cooked and to the trimmings that come with them. For example, poached eggs on wholegrain toast is a much healthier meal than a traditional fry up.”
How good was the research?
Strengths of the study include its large size, including nearly 30,000 people, and that participants were followed for a long time (17.5 years). The information collected about participants’ diets was also very detailed, meaning that the researchers could take into account how much saturated fat, meat, fibre and sodium they consumed.
Importantly, however, this was an observational study - rather than a trial with people being asked to consume different amounts of eggs – so it can only find associations, not a cause and effect. It’s possible, for instance, that people who already have a higher risk of heart disease and death due to other unknown factors also happen to eat more eggs.
Another weakness of the study is that people were only asked about their diets once, so the researchers had no way of knowing whether people changed their egg consumption over the course of the study.
How the research was reported
The Daily Mail said the study “reignites a fierce and controversial debate over eggs”, while The Times called it “the latest instalment in the ever-more complex debate on the role of cholesterol in ill health.” Most coverage outlined the strengths and weaknesses of the study clearly. The Mail pointed out the ‘cracks’ in the findings, such as relying on participants to remember how many eggs they had eaten over the past month or year, and the fact that they were only asked once.
Another comment piece in the Mail called the study’s authors “scramble-brained boffins”, and suggested that “people who eat two eggs a day could be consuming them as part of gut-busting fry-ups,” and it “could therefore be inordinate quantities of artery-clogging sausage and bacon rather than eggs that’s causing problems.” But this isn’t the case - a strength of the study was that it collected detailed information about people’s diets, allowing the researchers to account for the effects of other foods known to increase the risk of heart disease.