Can eating an egg a day reduce your risk of heart diseases?

Box of eggs

New research has suggested that a daily egg can reduce your risk of heart disease and stroke. We look behind the headlines. 

23 May 2018

Research published in the journal Heart suggests that a daily egg might be good for you. The researchers, led by Peking University, looked at the association between eating eggs and heart and circulatory diseases including heart attacks and stroke

They found that people who ate an egg daily had an 11 per cent lower risk of heart and circulatory disease, and an 18 per cent lower risk of death from heart and circulatory disease.  the biggest differences were seen in  risk of dying from haemorrhagic stroke (the kind of stroke caused by a burst blood vessel – less common than stroke caused by a clot) where the risk in daily egg-eaters was 28 per cent lower compared to people who didn’t eat eggs. 

The results were similar for men and women.

The participants in this study were all from China, so it is difficult to apply this to people who live in the UK

During 2004–2008 the researchers looked at the egg consumption and health information of more than half a million healthy adults aged 30–79, living in China. They then followed them up for an average of nine years.

During the follow-up, there were 83,977 cases of heart and circulatory disease and 9,985 deaths, as well as 5,103 major coronary events such as heart attacks.

The BHF view

Victoria Taylor, Senior Dietitian at the British Heart Foundation says: “This type of study can only show an association rather than cause and effect.  It’s possible that the lower risk of heart and circulatory disease may have been caused by something else in the diet or lifestyle of the people consuming daily eggs rather than the eggs themselves.

“However, it is reassuring for people who like to ‘go to work on an egg’. Although eggs are still often thought of as a food to be avoided, the current advice in the UK is consistent with the findings of this study: eggs can be included as part of a healthy, balanced diet.”

How good is the research?

Participants were asked to fill out a questionnaire, where they were asked whether, during the previous 12 months, they had eggs daily, 4 to 6 days per week, 1 to 3 days per week, 1 to 3 days per month, never, or rarely. This could be problematic, as it assumes that people eat the same amount of eggs throughout the year. There is also the risk that people might not have reported their egg intake accurately.

How you eat eggs matters too – eating them as part of a fry-up won’t deliver the same benefits as eating them with wholegrain bread and vegetables

The participants in this study were all from China, so it is difficult to apply this research to people who live in the UK.  The people in the “daily egg consumption” category actually averaged three quarters of an egg per day. A major weakness is that there was no group in the study who ate more than this, so it doesn’t tell us about the effects of eating larger numbers of eggs.

It’s also worth bearing in mind that the results from this study are inconsistent with previous studies. Seven other studies found that eating up to one egg a day had no significant association with coronary heart disease compared with consuming two eggs a week. This suggests more research is needed. 

A strength of the study was that the researchers took other things into account that could have caused the result they found, including alcohol consumption, smoking, physical activity, blood pressure, waist to hip ratio, and family history of heart and circulatory disease. This makes the findings more reliable. 

Media coverage

The story was widely covered, for example in The Sun, Metro, Independent, Daily Mail, and the BBC.

The Independent correctly pointed out that how you eat eggs matters too – eating them as part of a fry-up won’t deliver the same benefits as eating them with wholegrain bread and vegetables. However the Independent and Telegraph also suggested that the study only compared daily egg-eaters with those who never ate eggs. Although this is where the most significant differences were found, they found that eating egg less often than every day still seemed to deliver benefits versus not eating any eggs.

The Telegraph also quoted Professor Tim Chico, from the University of Sheffield, who made the important point that "It is very difficult to determine the part any single element of our diet plays in our risk of developing heart disease.”

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