Initial Posting: 9/17/2014    Last Update: 4/30/2020
Answer: If in a dry, powder form (tablets, capsules and powders for scooping), supplements containing whey protein and branched-chain amino acids (BCAAs) and won't break down within the range of temperatures normally experienced during shipping or in the home. Although higher temperatures may change their shapes, they will continue to provide the same nutritional benefits. Although they may clump with humidity, humidity and even water do not cause them to break down.
Digestive enzymes are stable until temperatures exceed 115° F (46° Celsius), at which point their shapes may change and this will affect their function.
Creatine, particularly in dry form, is stable within normal ranges in heat. However, humidity or water can cause creatine to degrade — which is why ConsumerLab has found some liquid creatine products to have degraded into creatinine, a different compound.
To reduce exposure to moisture, especially in humid climates, it's best to store powdered products in several small containers rather than one large container. Do not store these supplements in the refrigerator, because if you remove them and leave them open, moisture may accumulate due to condensation.