Vitamins Stored In Bathrooms or Kitchens May Become Less Effective

A new study shows high humidity and temperatures such as those found in the bathroom and kitchen can quickly degrade the potency of vitamin C and shorten the shelf life of vitamin supplements even if the bottle lids are on tight.

Researchers found the most common types of vitamin C used in vitamin supplements and other fortified products are prone to a process called deliquescence, in which humidity causes a water-soluble substance to dissolve.

Long shower/High humidity

“Opening and closing a package will change the atmosphere in it. If you open and close a package in a bathroom, you add a little bit of humidity and moisture each time,” researcher Lisa Mauer, associate professor of food science at Purdue University, says in a news release. “The humidity in your kitchen or bathroom can cycle up quite high, depending on how long of a shower you take, for example, and can get higher than 98%.”

“Humidity and Vitamin C Don't Mix”

Mauer says, “If you get some moisture present or ingredients dissolve, they’ll decrease the quality and shelf life of the product and decrease the nutrient delivery, within a very short time, in a week you can get complete loss of vitamin C in some products that have deliquesced.”

Powdered vitamin C is a popular ingredient for food fortification and is one of the most commonly added nutrients to vitamin supplements. Researchers say because vitamin C is very unstable and its content must be declared on nutrient labels, it is commonly used as an indication of the shelf life of foods and supplements. Once humidity is decreased, the product will solidify, but by then it’s too late, the damage has already been done. So keep the supplements away from humid and warm environment to help in ensuring effectiveness.

Alert to Brown spots

Mauer says, the first signs of nutrient degradation are usually brown spots, especially on children's vitamins and suggested discarding dietary supplement showing signs of moisture uptake or browning. “Why to give a vitamin to a kid if it doesn't have the vitamin content you're hoping to give them?” Research findings suggests to store products in dry conditions, below their deliquescence relative humidities, can avoid unwanted ingredient loss.