Can Vitamins Turn Poisonous?

After Googling around and reading a few articles, we got our answer. No, vitamins don't go bad and they don't turn into poison. Vitamins are not like food and don't "spoil" per se. That is they won't make you sick if you eat them past the expiration date. So if you see a bottle with expired vitamins, feel free to take 'em.

The bad news is that they're not as effective. The expiration date on the bottle is there to confirm the last date of the vitamin's full potency. After that date, vitamins start to lose their supplement values. They can reduce by 10% or 20% quite quickly. We couldn't find an exact answer since all vitamins are different but all research seems to agree that the vitamins just won't be as nourishing. Not ideal but at least you won't die.

And if you're wondering about taking more vitamins to double up, that usually doesn't work and might actually cause more harm than good. First off, your body won't absorb all the extra nutrients. We can only handle so much at one time. Secondly, too much of one nutrient may cause a deficiency of another. For example, iron and zinc are absorbed through the similar binding sites in your body. This means if your body is absorbing all the iron, there's no room to absorb the zinc and the zinc simply passes through.

Lastly, store your vitamins like you would store your walnuts! Limit them from exposure to air, light, and moisture. All of these elements can cause vitamins to decay sooner and lose their potency faster. The best thing to do is to store them in a cool, dry place. ​

Here's a few more articles to read if you're interested in learning more: