Superstar athletes such as LeBron James, Peyton Manning and Derek Jeter probably drink them often. Millions of other Americans make them part of their regular diet, too.

But can protein shakes be bad for you?

The dietary supplement, which often comes ready to drink or in powder form, is a great way for people to get sufficient amounts of protein. It also repairs and builds damaged muscles following intense workouts.

However, there are apparent dangers. A Consumer Reports investigation found traces of heavy metals such as arsenic and lead in 15 different protein drinks that were tested. Consumption of those substances can cause health problems, especially for children under 18, pregnant women and people with diabetes or chronic kidney conditions.

However, a spokesman for one of the brands tested said the substances found in the protein shakes are also found in agricultural products such as fruits and vegetables.

A benefit to these shakes is that the body absorbs the protein much quicker than it does food. But that can pose more harm, as experts say it is possible to take in too much protein. Excess protein can harm the kidneys and increase the risk of heart disease.

Also, if a person drinks shakes in place of meals each day, he or she could develop nutrient deficiencies over time.

Protein shakes can be of great benefit if you’re looking to add muscle, improve athletic performance or simply ensure you’re including sufficient nutrients in your diet.

It’s recommended, though, that you treat protein shakes as a supplement, and not as a complete meal replacement. Don’t consume them in excess. And ultimately, consult your doctor before beginning a regimen that includes regular consumption of shakes.