Unscrambling the truth about eggs: as they're linked to a shorter life, should you or shouldn't you?

The story of egg consumption in this country has been a colourful one. A key ingredient in the traditional full English breakfast, eggs have nonetheless fallen in and out of favour over the past few decades, owing to health claims made variously for and against them.

Until recently, we seemed to have settled on the view that eggs were not only fine, but actually pretty good for us too. The NHS recommends them as part of a healthy, balanced diet, pointing out that as well as being a source of protein, they also contain a number of vitamins and minerals. There is no official recommended limit on how many eggs we should eat.

But a new study casts doubt on one of our favourite foodstuffs all over again. Chinese researchers have found that eating whole eggs increases your risk of early death. According to the study, a person eating one egg a day has a 14 per cent greater chance of early death than someone who avoids eggs altogether.

"In this study, intakes of eggs and cholesterol were associated with higher all cause, cardiovascular disease and cancer mortality," said the study's co-author, Professor Yu Zhang, of Zhejiang University. "The increased mortality associated with egg consumption was largely influenced by cholesterol intake." The researchers suggested people eat only the white of eggs, or substitute them altogether for nuts or legumes.

It follows a study last year by researchers at the University of South Australia, who studied a sample of 8,545 Chinese adults and concluded that eating just one egg a day increases the risk of developing type 2 diabetes by 60 per cent.

"Diet is a known and modifiable factor that contributes to the onset of type 2 diabetes, so understanding the range of dietary factors that might impact the growing prevalence of the disease is important," said epidemiologist and public health expert Dr Ming Li from the university.

This is unarguable, of course. But what is perplexing is that the body of research on eggs seems so contradictory. Only in 2019, experts at the University of Finland suggested that eating one egg a day was associated with a lower risk of type 2 diabetes. The American Diabetes Association, moreover, recommends egg consumption for those who already have diabetes.

Dr Li acknowledged that the association between eggs and diabetes was “often debated” but explained that this latest study had aimed to assess people's long-term consumption of eggs and their risk of developing diabetes, as determined by fasting blood glucose.

"Over the past few decades China has undergone a substantial nutritional transition that's seen many people move away from a traditional diet, comprising grains and vegetables, to a more processed diet that includes greater amounts of meat, snacks and energy-dense food,” he said. "At the same time, egg consumption has also been steadily increasing; from 1991 to 2009, the number of people eating eggs in China nearly doubled.”

However, more research was needed to explore causal relationships between egg eating and diabetes, he added.

Is it OK to maintain your egg habit in the meantime? The existing evidence would suggest so. Much of the fear around egg consumption in the past has centred on their high cholesterol content. High cholesterol levels in our blood increase our risk of heart disease, but it does not necessarily follow that eggs therefore increase our risk of heart disease. The amount of saturated fat we eat has more of an impact on our blood cholesterol level than the cholesterol we consume in eggs, says the NHS.

In 2019, the British Heart Foundation offered a measured reaction to a US study published in JAMA that linked high levels of dietary cholesterol, such as that found in eggs, to an elevated risk of heart and circulatory disease and even death. Again, the research showed an association but did not prove cause and effect, the charity noted. Again, more research was needed to understand the reasons behind the link, argued Victoria Taylor, senior dietitian at the charity.

The case against eggs, then, would seem to remain unproven, while the case in favour looks strong.

We’ve come a long way since Edwina Currie, then Conservative health minister, warned in 1988 that most of Britain’s egg production was infected with salmonella bacteria – a claim whose factual accuracy was bitterly disputed but which affected public attitudes to eggs for many years afterwards. The British Egg Industry Council said at the time the risk of being infected with salmonella was less than 200 million to one.

Today, it’s not hard to find nutritionists with a positive take on eggs.

“Eggs are one of the most nutritious foods on the planet,” says nutritionist Rhiannon Lambert. “There has been talk about how eggs may increase the risk of heart disease. However, many studies have examined this and found no association between the two. They have also previously been demonised owing to their high cholesterol content.

“It is now widely accepted in research that the dietary cholesterol they contain is actually beneficial rather than detrimental. In fact, eggs have been linked with more health benefits than health risks.”

Poached eggs and avocado have powered this country’s millennials for several years now. Boiled eggs and soldiers still power the nation’s children. Judging the evidence available today, there seems little reason to stop.