The calcium issue is much more of a concern for giant breeds like the Great Dane, yet TOTW is one of the top reccommended and used foods out there for our breed. It is a great choice for grain free kibble. The fact of the matter is, we will always find something in the ingredients in ANYTHING we ingest ourselves, or feed our dogs, that isn't the absolute best for us. It all comes down to choosing the best we possibly can...really there's not much else you can do. As more and more people are becoming interested in just what we feed our pets, these studies and theories will come out of the wordwork, like we are now seeing. If your dogs are doing good on this food, and you're otherwise happy with the product, then don't stress yourself too much. Trust me I know. I spent a year making myself almost sick worrying about food for Luke Also, it's the calcium/phospherous levels that are important, not just the calcium. U can have foods with less calcium but the incorrect ratio to phospherous and have more problems. Or so some say.
Over all, I love this food..I reccommend it to all giant breed owners as a great option.