Thursday 18 October 2018

Does an egg a day keep the doctor away?

New evidence shows they boost heart health. Tomé Morrissy-Swan unscrambles the science

So eggs actually lower your risk of heart disease? It's time we unscramble this confusing story. (File pic: PA)
So eggs actually lower your risk of heart disease? It's time we unscramble this confusing story. (File pic: PA)

The egg has something of a chequered past. In the 1950s and 1960s, they were heralded as the best way to start your day with the famous "go to work on an egg" advertising slogans. But by the 70s, received wisdom had almost flipped on its head: eggs were the bad boys of nutrition, carrying a dangerously high level of cholesterol, which had been linked to an increased risk of heart disease. Limit your intake to three a week, was the thinking - and never have two at once.

So you'd be forgiven for thinking twice before cracking open your egg in the morning. However, despite those decades of negative PR, the macro-history of eggs is very positive. They've long been seen as a reliable, nutritious, cheap and tasty form of nourishment. In many cultures and religions, eggs are a symbol of life and rebirth - and who can deny their replenishing properties on a particularly heavy hangover?

This century, as our understanding of nutrition improves, eggs are firmly back on the menu. No longer a culinary outcast, eggs, particularly poached, scrambled or baked, are a brunch staple, and have become one of the most instagrammed foods around.

Indeed, a new study has revealed that eating an egg a day may reduce the risk of strokes and heart disease.

Researchers from Peking University Health Science Centre in China observed the egg-eating habits of 416,213 participants. Those who reported daily consumption of eggs at the beginning of the nine-year study were found to be at lower risk of the diseases than those who never or rarely ate eggs.

* So eggs actually lower your risk of heart disease? It's time we unscramble this confusing story.

For years, eggs were to be avoided because they were high in cholesterol. A large egg contains roughly 185mg of cholesterol, and the American Heart Association used to recommend a maximum of 300mg of cholesterol per day - so two eggs would see you over the limit. As cholesterol was linked to heart disease, it was logical that eating too much would be dangerous. Warnings were issued, and egg-phobia was disseminated.

Cholesterol is a substance found naturally in the body and produce by the liver. It plays a crucial role in how our cells work, and is required to make Vitamin D, hormones and bile. Too much cholesterol in your blood can accumulate on artery walls, which increases risk of heart attacks and strokes.

But here's the thing: the cholesterol in food has "very little effect on the cholesterol in your blood. It's much more to do with the saturated fat in food" says nutritionist Fiona Hunter. A boiled egg has about 3.3g of saturated fat per 100g; for butter, the figure is 51g per 100g.

Saturated fat, found in meat and dairy products as well as foods containing coconut or palm oil, will up the levels of cholesterol in the blood. Unsaturated fats (oily fish, nuts, seeds, avocados, vegetable oils) can actually lower cholesterol levels.

To understand how this works, you have to know that there are two types of cholesterol: high-density lipoprotein (HDL) and low-density lipoprotein (LDL), otherwise known as "bad" and "good" cholesterol. HDL is considered good as it transports excess cholesterol to the liver, where it can then be expelled by the body, rather than stick to your arteries. LDL ushers the cholesterol to your arteries which can build up causing potential blood clots (and by extension lead to heart attacks or strokes).

* How do eggs effect LDL and HDL cholesterol levels? A study from the University of Connecticut found that those eating three eggs a day for a month registered no change in ratio between the two types of cholesterol, implying no difference in risk to heart health. A later investigation at the same institution, in 2012, discovered that LDL cholesterol did not rise in middle-aged people who had eaten three eggs per day, though levels of good cholesterol were boosted.

The recent findings are the latest in a line of research suggesting the health risks of eggs have been overplayed in the past. In 2013, an investigation published in the British Medical Journal claimed that an egg a day, if not keeping the doctor away, would not negatively impact heart health.

* So does it keep the doctor away? "Nutritionists and dietitians have always known

that eggs are a very nutritious food, for lots of reasons," explains Hunter. "They're a very good source of several vitamins and minerals, some of which, like iodine and Vitamin D, are difficult to find in other foods. They're a real powerhouse of nutrients and protein."

A medium egg contains, among other nutrients:

• 63pc of recommended intake of Vitamin D, useful in a country where most people are deficient.

• 36pc daily requirements of Vitamin B2, vital for growth and bodily repair.

• 108pc required daily Vitamin B12, essential for the body's nervous system and blood cells, as well as producing DNA.

• 39pc daily requirements of biotin, for metabolism, nerve, and digestive and cardiovascular functions.

• 71pc of necessary daily Choline, important for liver function and brain development.

"They've also got iodine and selenium," says Hunter. "One medium-sized egg would provide 42pc of your recommended daily amount of selenium and 34pc recommended iodine." Iodine is especially important for pregnant women, as it's linked with your baby's IQ. "As people turn away from milk our iodine levels are dropping, so eggs are a good way to get it into the diet."

"They're also incredibly convenient, quick and versatile. I'm a big fan of eggs, and would probably eat them for lunch two or three times a week. The smashed avocado on toast with a poached egg on top has introduced a whole new generation to the joy of eating eggs. And they're an excellent source of protein for vegetarians too."

› Should we be limiting our egg intake, then? "I haven't seen any recent research suggesting we should," Hunter continues. "Having said that, we need to eat a variety of foods. I don't think there's any harm in having eggs every day, but the only caveat is your diet would not be hugely varied."

And, of course, the way we eat them can have a big impact on how healthy or unhealthy they are. A fried egg with lots of salt is evidently not as wholesome as a boiled egg. "A boiled egg is a very good snack that isn't too calorific but still very filling."

Health & Living

Life Newsletter

Our digest of the week's juiciest lifestyle titbits.

Editors Choice

Also in Life