If you take vitamins or supplements on a regular basis, you know buying them can be a pricey investment. In order to keep their potency, be sure to store them properly. Keep your vitamins in a cool, dark place. This means bathrooms, with steamy air that can quickly decrease the shelf life of vitamins, are a no-go. But also keep them out of the fridge, which is still too humid and can ruin the pills. Instead, the coolest cabinet in your kitchen is the best place for them.