For anyone who take vitamin supplements, you'll notice they all say to keep them out of direct light. Basically vitamins lose their potency when exposed to light. So if I keep my vitamins in a see-through container, how much potency am I losing over what period of time? I tried to search the web but did not see any real answer, some of you probably know more than Google.

Let's say I am and I keep my daily pills in a see-through box (one compartment for each day of the month). I fill all the compartments up at the beginning of the month with my pills. By the end of the month, will my vitamin pills have any potency left or have I just wasted them? Thanks.

 

I have no idea. I don't worry about stuff like that, but I'd say within such a short time frame, I don't see any harm, but what do I know?

BTW, I don't totally buy into the fact that drugs expire EXACTLY one year from the time my pharmacist fills the script.

 

It is hard to say how fast they will degrade. The requirement is set by the company manufacturing the pill or if it is a more generic item the specifics are set by the USP (United States Pharmacopeia).
They do stability studies to claim how long the claimed potency will last (this includes container, light, and heat). The manufacturer has to set aside samples from each production run and store them as claimed. Per protocol they go back and validate the claimed potency.

If you only have a months supply out in light (remember this is direct sun light not diffused) they should be fine. As an aside if you stored them in a cabinet or just kept them out of direct light they would be fine until you consume the entire amount.

One other point is that if a product is labeled "USP" regardless of manufacturer or cost it is all the same.