Here's the best way I can explain my take: check the label for sodium per serving (note the serving size...it's usually a very small serving). If sodium is a concern for you due to health reasons, you definitely should not introduce more of it. If salty taste is a concern, you don't want more sodium, either. It's already injected, so should be treated as compromised muscle (40/140*/4hr guideline). That said, if your reason for wanting to brine is to further enhance the flavor, as I'm sure it is, you could inject your own spice solution or dedicated marinade, with reduced/no-salt added.
The only way brine can do any good is if the salt content in the brine is higher than the salt content of the meat. The brine will absorb into the meat through the process of osmosis, and this is accomplished with salt. Given enough time, the salt content of the meat will equalize with the brine, and then, osmosis stops. By injecting, you save time and fridge space, and omit the salt in your injection solution if you wish, which then doesn't add to you sodium intake.
There is a myth about birds getting dry because they're not injected or brined...not true. Cook to internal temp of at least 165* as measure by a thermometer and they will be safe to eat. Keep the finished internal temp under the 175-180* range and they will not only be safe, but they will also be juicy. Over 180* is pushing it way too far...dry and tough will be the norm. I shoot for 170-172* in the breast and 172-175* in the dark meat...due to the pink/red color around the bones at lower temps...those areas cook a bit slower.
As of late, my birds don't get any brine or injection. I cook to temp and have never had any complaints. Use your seasoning of choice or your own blends, inside and out, and cook to temp.
Eric
