Protein powder pros and cons: What to know, what to watch out for

Story highlights

  • Convenience is the top benefit protein powders offer, especially for athletes
  • Too much protein -- starting at about 35% of daily calories -- can lead to health issues

(CNN)Protein powders are expected to be a $7.5 billion industry by 2020, and the products are popular for a wide variety of reasons: Vegetarians might feel that their diets are somewhat lacking, athletes may want to add muscle faster or aim for a competitive edge, and still others might be looking for a quick meal that isn't dripping with grease.

And there's an equally wide variety of products on the market. Here's what you should know about protein powders.
    Protein is an important building block for muscle as well as hair, skin and nails. Powders are dehydrated forms from sources such as milk, soy or plants. They're typically mixed with water or other beverages, or they can be added to foods to boost protein content.
    Athletes' protein needs can be up to twice those of the average person because of the energy they expend and the process of breaking down, repairing and building muscle. Many vegans also use protein powders in lieu of animal-based sources such as meat, dairy or eggs.
    The recommended dietary allowance for protein is about 0.8 grams per kilogram of body weight each day, which translates to 54 grams for a 150-pound person.
    However, "I think those estimates are a little conservative," nutritionist and health journalist