Stored properly, vitamins are usually stable for a minimum of four or five years, according to Glen M. Shue, a chemist/ nutritionist for the Food and Drug Administration, but he added: ”We had a bottle of vitamin D on the shelf in the lab for 10 years. We’re air-conditioned so the temperature stays cool here and when we tested it, it was still good. So it’s hard to tell.
An expiration date is conservative and aimed at the manufacturer and storer more than the consumer. That keeps them from selling the stuff that they have in the warehouse for years.
If you’ve got a bottle a few years past its expiration date, you can go ahead and take them. They’re not dangerous and they’re probably still mostly good. Stored properly, vitamins can last four or five years. Taking vitamins beyond an expiration date is generally safe. But in case you have doubts, some vitamins have been known to last 10 years or longer without losing their label strength.”
Expiration dates are extremely conservative. All vitamins start to slowly degrade the day they are manufactured. Vitamins deteriorate at different rates, so manufacturers will beef up the strength of some vitamins that tend to deteriorate faster, in order to hit the listed strength at the time of expiration.
If you were to purchase vitamins on the day they’re manufactured, in some cases you’re actually getting a higher strength than what’s listed on the label (to allow for deterioration over time).
Vitamins are listed as “supplements,” thus are not regulated by the FDA. As supplements, vitamins are not required to list an expiration date on their label.