The molecules of which foods are made are too large to pass through the lining of the digestive system. Digestion results in the formation of smaller molecules that are able to pass through that lining and enter the person's bloodstream. (for example,) Sugar molecules formed by the digestion of starch enter the bloodstream.
Either way, not worth the risk - you can get very ill from consuming or drinking expired products, including ice tea. Now if it is a best before date, that tells us something else. It says it has not turned or gone bad, but that it may not taste very fresh after the date on the bottle. There is a huge difference between the comments expired and best before - so please use caution and consider these points. For dry ice tea mix, you usually see a best before date.
Photo Credit TongRo Images/TongRo Images/Getty Images. It may be safe to drink Lipton green tea and other dried teas beyond their expiration dates. According to Lipton's website, the expiration date is actually a Best if used by date. This means that after the given date, the product may lose some of its flavor and healthful components and decrease in overall quality, so it's recommended to drink the tea before this date.