I was planning on picking up some supplements for various areas of general health, and was looking into NAC, as it's pretty cheap, and then I remembered I have an old bottle bottle of 150g NAC powder. It says it was manufactured in 12/2013, which makes it about 2.5 years old. Should I just use this, or since NAC is pretty cheap anyway, just pick up some new NAC? It's been opened, but has been closed (lid on) in a cool and dark-ish environment the whole time. Thanks.