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What to Look For in a Protein Powder

Protein is a critical nutrient, but finding the right protein powder means ensuring that what’s in the bottle is really protein.

CrossFit athletes are not that different from football players and bodybuilders when it comes to identifying protein as the most important nutrient for making gains in muscle and performance. Nor are they different in expecting the information on protein-powder labels to be straightforward. However, a couple of recent developments in the nutrition community — both regarding the practice of “protein spiking” — suggest that the potential for confusion still exists when it comes to deciding which protein supplement to buy.


Amino Spiking

The April 2014 issue of Natural Products Insider included an article titled “Pure Protein Products” that highlighted a key issue in the sports-nutrition industry. “Amino spiking” or “protein spiking” is the process by which additional amino acids or creatine are added to a protein product as a cheap way to inflate the protein content listed on the Supplement Facts panel. Right around the same time that the article was published, the American Herbal Products Association released a guidance statement regarding how to properly label protein products in order to make it easier for consumers to decide which product to buy. 

In essence, the AHPA suggested that protein listed in the Supplement or Nutrition Facts panel should represent intact protein, made up of amino acids linked together in their more natural protein form.

The “Watch Out” Ingredients

It’s important to understand that the article and the AHPA guidance statement aren’t saying that amino acids, creatine or other nitrogen-based ingredients can’t be added to protein supplements. On the contrary, they are certainly allowed in protein-based supplements; they just shouldn’t be counted toward the protein content. That said, the Natural Products Insider article identified glycine, taurine and creatine as the ingredients most often used in protein spiking. Part of the argument against the practice is that two of those “aminos,” taurine and creatine, aren’t used as building blocks of protein at all, so obviously they shouldn’t count toward a product’s protein total. 

Meanwhile, while glycine can be used as a building block for making protein in muscle, it is perhaps the least essential of the amino acids and only serves to dilute the amount of the essential amino acids in the product including leucine.

The “Look for” Ingredient

Leucine, arguably the most critical of the essential branched-chain amino acids, is important to muscle growth and improving performance and strength because it seems to directly ramp up protein manufacturing in muscle. The Natural Products Insider article suggested that leucine content can be used as a means of gauging the quality of a product. If other amino ingredients are added to a product, leucine is diluted and potency can be reduced compared to intact protein.

In general, milk proteins like whey and casein are the highest in leucine content, with leucine representing as much as 11 percent of the protein content. So a whey, casein or milk protein product should contain 10 percent or more leucine, or 2.5 grams in a serving providing 25 grams of protein. (Egg, soy and other vegetable proteins should have at least 2 grams of leucine in that same 25-gram serving.) That means that you should specifically seek out brands of protein powder that report their amino content on the label and then make sure that a bottle of, for example, whey protein powder that offers a serving size of 25 grams should contain 2.5 grams of leucine. 

So, to make sure you’re getting the best product for the money, dig deep into the ingredients to look for extra aminos that might be used to drive up protein claims. And remember that if a protein product is a lot cheaper than other reputable products sitting next to it on the shelf, the reason might just be amino spiking.

Robert Wildman, Ph.D., RD (, is the author of Sports and Fitness Nutrition and The Nutritionist: Food, Nutrition, and Optimal Health. Follow him on Twitter:@TheNutritionDoc.