Senior nutritionist Rose Carr looks at the latest science and puts it into context for everyday life.
How eggs got a bad reputation
In the 1950s we were encouraged to eat eggs regularly, preferably every day. Then scientists discovered a link between fat in the diet and heart disease.
Eventually they concluded not all fat was bad, it was saturated fat that caused the problems. Saturated fat and cholesterol in foods often go hand in hand, so foods containing saturated fat and/or cholesterol became implicated. Eggs are one of the few foods high in cholesterol but with little saturated fat. Around the world people were warned to limit their consumption of eggs.
What science says now
With our improved understanding of fats and cholesterol we now find there is no evidence of a link between dietary cholesterol and heart disease risk, whereas the link between saturated fat and heart disease risk is clear. Large studies in the US have found the risk of heart disease is similar for people eating less than one egg and those eating six eggs each week.
The only cautionary note still sounded is that the research shows a possible increased risk for those with diabetes.
Why we should eat more eggs
It now seems that for most of us, restricting eggs in our diets may have negative consequences for health.
Apart from liver, eggs are the richest source of the essential nutrient choline. Pregnant or breastfeeding women have a high need for choline as it plays a key role in brain development both before and after birth, and low choline levels are associated with neural tube defects in newborns. Low choline has also been found to be associated with markers for heart disease and animal studies have found it is also linked with memory and cognition. US studies have shown most adults do not get adequate choline in their diet.
The yellow in egg yolk is from the carotenoids lutein and zeaxanthin, antioxidants shown to be critical for maintaining eye health. Also found in broccoli, spinach, green beans and oranges, lutein and zeaxanthin in eggs are much more bioavailable.
And for anyone interested in weight control, eggs have been shown to have high satiety: they keep you feeling full for longer than many other foods. So have an egg for breakfast or lunch for fewer kilojoules in a day.
Bodies that make food and health-related recommendations to the public don't change their recommendations in haste. In the past they'd all advised limiting egg consumption but now heart associations around the world, including New Zealand, no longer advise limiting the number eggs most people should consume.
In August 2009 the Australian Heart Foundation went even further and now encourages people to consume up to six eggs each week.