Most people know there are two kinds of it, HDL cholesterol (the good kind) and LDL cholesterol (the bad kind). Of the 230 milligrams of cholesterol in a large egg, a large part is the good kind that helps eliminate the bad kind and keep plaque from building on blood vessel walls.

"I don't think that avoiding cholesterol by simply skipping the yolk brings peace of mind," says Wang, "because all the abundant nutrition in an egg lies in its yolk."

Egg yolk contains unsaturated fatty acid (and saturated fat), vitamins A, B2, B6, D, E, potassium, sodium, magnesium, iron, phosphorus, and other micronutrients.

Therefore, he says, healthy people without high blood pressure and high cholesterol don't need to worry too much about eggs under certain daily dose.

According to Wang, children and young people need an egg a day for nutrition; elderly people, especially those with hypertension, high blood fat or high blood sugar, should limit themselves to one egg every third day.

What's the best way to eat eggs?

Some people think eating eggs raw is the best way to get all the nutrition. That way, however, inhibits nutrition uptake. Nutrition is not as bio-available as in cooked eggs.

A raw egg contains antiglobulin that inhibits digestion and absorption of protein. Protein in raw egg is less bio-available than in cooked egg.