At this time, since there are no domestic sources, all amino acids are manufactured in China. We have no data that any of these amino acids are toxic in any way if used in correct dosages.
We agree that it would be nice to not add ingredients from sources outside the U.S. But we must face the supply reality and feel incorporating these nutrients is important enough to make the compromise. Not doing so puts pets at great risk. For example, hundreds of thousands of cats suffered from a taurine deficiency, many of them dying, as a result of what processing does to taurine. Only when taurine (from China) was supplemented to pet foods was this terrible problem reversed.
We purchase these ingredients from trusted U.S. suppliers, some of which we have been working with for decades. With the limited options available, we believe that having these ingredients included is a far better option than not including them at all.
Our 35 years of feeding hundreds of thousands of animals through multiple generations, some Wysong-fed pets now living beyond their mid-twenties, gives us confidence in our ingredients.