I've been in e-mail contact with WPC, so I've edited out non-essential info from the letter.<br><br>Me: "When the tabs have changed colors, is<br>this a sure fire sign that the tabs have gone bad?"<br><br>"Not necessarily. The tablets do change color over time this is OK. When the tablets turn whitish and have a crumbly texture the tablets have expired.<br><br>Once the bottle is open, the seal is broken. Opened bottles will only last approximately one year.<br><br>Sincerely<br>Jean xxxxxx<br>Regulatory Coordinator<br>WPC Brands<br>800/ 558-xxxx"<br><br>I hope this helps.