Protein ping-pong. (updates).(amount of protein need in ideal diet unknown)

Over the decades, experts have bounced back and forth on the amount of protein needed in the ideal diet, with no consistent advice for confused consumers.

But finally, amid the controversy, nutritionists at the October 21, 2002 meeting of the American Dietetic Association in Philadelphia basically admitted that they really don't know how much protein North Americans need.

The public has been bombarded with conflicting advice on the benefits--or dangers--of carbohydrates, fats and protein. But protein illustrates the problem best.

Nutritionists in the 1960s told the public they would be healthy if they ate lots of meat. Then, over the next two decades, health experts promoted high-carbohydrate diets and warned against eating too much protein.

When the low-carbohydrate, high-protein Atkins' diet debuted 30 years ago, and again after its recent resurgence, experts came out strongly against it, saying protein--along with fat--is what is killing us.

Too much protein may even hurt the kidneys and weaken bones, says the American Heart Association. Excess protein reduces the body's ability to absorb calcium after just six weeks, concludes a study in the August 2002 issue of the American Journal of Kidney Diseases.

And the weight loss associated with high-protein diets may actually be simple fluid loss, some experts say.