The Claim: Always Store Vitamins in the Medicine Cabinet
THE FACTS The medicine cabinet may seem like an ideal place for keeping vitamins
and supplements. But research suggests otherwise.
In studies, scientists have found that the warm, moisture-rich conditions found
in most bathrooms tend to degrade vitamins and other supplements over time.
Researchers have found that this process, known as deliquescence, can reduce the
potency of vitamin B, vitamin C and other water-soluble supplements — even
rendering them useless. Airtight lids do not necessarily solve the problem,
since opening and closing them allows humidity and moisture to get in.
In a study published this year by food scientists at Purdue University,
researchers measured the stability of different vitamin C supplements in various
temperatures and levels of humidity. They showed signs of degradation above 80
percent humidity, a level of bathroom humidity that the steam from a hot shower
Other studies have found similar effects on thiamin, vitamin B6 and other
water-soluble nutritional products exposed to humid environments.
Humidity levels can spike in kitchens as well.
For best results, try keeping vulnerable products — like multivitamins, children’s vitamins or powdered health products — in a cool, dry area with little humidity, like your bedroom. If your
vitamins soften or develop dark spots, it means they have already started
degrading and should probably be discarded.
THE BOTTOM LINE Storing vitamins in a medicine cabinet and other humid areas can
reduce their effectiveness.