How to Prevent Your Supplements From Losing Their Potency   Dear Reader, When dark spots develop in supplement capsules, you know that can't be good. But this is a common problem when supplements are exposed to one or more of the three thieves of potency: temperature, humidity, and light. Fortunately, there's an easy step you can take to control those thieves. And you'll not only avoid dark spots, you'll also be sure to get the very highest potency out of your daily supplements. Stop, thief! The one place in the home that's specifically designed to store medicines — namely, the medicine cabinet — turns out to be the worst place to store drugs and supplements. Humidity is the primary culprit. After a shower, your bathroom is damp and muggy and because humidity like that can be penetrating, Perdue University researchers conducted an experiment to see how vitamin C holds up under various temperature and relative humidity conditions. The quick answer: Not so good. High temperature and humidity (especially humidity) had significant effects on degradation of vitamin C supplements. Needless to say, in the midst of cold and flu season, you'd want to get every bit of the potency from your daily vitamin C. The Perdue team writes: "This research highlights the importance of considering phase transformations when constructing shelf life models and maintaining vitamin C in the solid state for enhanced stability." That's a scientist's way of saying, "Get the supplements out of the bathroom — now!" More specifically, it's the water soluble vitamins that degrade when exposed to bathroom humidity. Here are the eight water-soluble:  * Vitamin C  * Vitamin B1  * Vitamin B2  * Vitamin B6  * Vitamin B12  * Niacin  * Folate / Folic acid  * Pantothenic acid