Whey Protein Alone Won't Cover the EAA Requirements of Hard Working Athletes, Study Says. Plus: US Whey More Digestible & 88% Higher in Leucine than Brazilian Whey

Not all protein supplements are created equal. And this goes for whey supplements from different countries, too.

In their accepted manuscript for LWT - Food Science and Technology, Cristine Couto Almeida and her colleagues write: "When the calculated AAS and PDCAAS based on the suggestion for adult athletes were considered, both [US & Brazilian whey protein] supplements exhibited suboptimal score values for several EAA [... and] were unable to supply the suggested adult athlete EAA requirement" (Almeida. 2014).

Shocked? I'd hope not. I mean, you don't even know what the scientists base their conclusion on - right? So before we even try to put things into perspective, it would be wise to take a look a the design of this in vitro study.
While the researchers from the Universidade Federal de Rio de Jaieiro acknowledge that whey protein, in general, is an effective adjunct to the diet of strength and even endurance athletes, they insist that there is too little "information regarding the WP supplement protein quality" and thus set out to "to investigate the protein quality of commercial WP supplements produced by U.S. and Brazilian companies based on in vitro digestibility (IVPD) assay, EAA, AAS and [protein digestibility-corrected amino acid] PDCAAS." (Almeida. 2014)

To this ends, the researchers acquired fifteen samples of whey protein (WP), soy protein, and caseinate isolate powder from a commercial retailer specialized on nutritional supplements. The supplements had been manufactured at different countries - eight from USA companies (WP-USA), and seven from Brazilian companies (WP-BRA). The supplements manufactured with soy protein and caseinate isolate powder were used as references in a study that yielded quite surprising results.

Figure 1: Essential amino acid composition of two commercial whey protein supplements (Almeida. 2014).

As you can see in Figure 1 the amino acid composition of the whey proteins from Brazil and the US varied significantly. The US whey, for example had significantly higher amounts of leucine, while the Brazilian whey was loaded with the essential amino acid lysine. While it is possible that the variations in the other amino acids are a result differences that were present in the milk, already, I would guess that the US whey was either openly (the scientists don't disclose the brands, otherwise I'd check) or secretly spiked with leucine to promote muscle anabolism.
Even if we assume the latter was the case and the producer added free form amino acids to the whey, though, this does not explain the other differences, because if you add say 20g of leucine to 100g of EAA and measure the amino acid content of the 100g of your new mix, the content of all other amino acids would be lower.

 As you can easily see in Figure 1, though, this was not the case in the study at hand. Plus: There were also significant differences in the protein digestibility-corrected amino acid composition, i.e. the marker of whether or not the content of a certain essential amino acid per gram of protein was sufficient or not. In that, values <1.0 indicate there is too little of this amino acid in the mix.

Figure 3: Amino acid score and protein digestibility-corrected amino acid composition for the commercial US and Brazilian whey supplements (Almeida. 2014).

As you can see in Figure 3, the latter was the case for threonine and valine in the US whey and for isoleucine and leucine in the whey protein from Brazil.
References:

• Almeida, Cristine Couto, et al. "In vitro digestibility of commercial whey protein supplements." LWT-Food Science and Technology (2014). 
• AOAC International, and George W. Latimer. Official Methods of analysis of AOAC International. AOAC International, 2012.
• Hsu, H. W., et al. "A multienzyme technique for estimating protein digestibility." Journal of Food Science 42.5 (1977): 1269-1273.
• WHO. "Protein and amino acid requirements in human nutrition." World Health Organization technical report series 935 (2007):