I just checked the ingredients on my organic Costco chicken stock. The ingredients do not contain MSG. I found a website that asked Costco about their "natural flavors" and got a response that it does not contain soy, or dairy, and no MSG is added.
Chicken stock contains natural glutamate because chicken itself contains it. It’s what gives chicken stock its savory flavor. Moreover, your body makes its own glutamate, too. So yes, it’s that simple. That’s why they say “no MSG is _added_”. This is similar to how a lot of meat products say “no nitrites are added”, yet use celery juice which is naturally rich in nitrites to prevent meat from turning brown.
The stock contains sodium and it contains glutamate from the protein in the chicken. It therefore contains MSG in the same way that salt water contains salt.
Is it really that simple? Please explain.