Is Refrigeration Better?
The simple answer is Yes. Probiotics are typically freeze dried to create a longer preservation time, just like instant coffee. If bacteria are dried in low temperature and stored properly, they remain alive, just dormant. They start to grow again when the environment is moist, such as inside the body. However, not all of the bacteria are alive. The survival rate of the freeze dried, dormant bacteria that have been stored in a refrigerator is about 50% to 80% (1). The survival rate goes down to just around 30% when it is stored at room temperature.
Dead Probiotics Are Also Effective!
There are quite surprising reports that dead or killed probiotics have beneficial effects on the host, like how a "killed" polio virus can affect the immune system (2, 3). Dead or killed bacteria have certain protein biomarkers in their cell membranes that can elicit a response in our body. Therefore, the statement that probiotics must always be alive is not necessarily true.
Storage in a Refrigerator is Not Required.
Storing probiotics in a refrigerator may be ideal, but non-refrigerated probiotics are still functional.
- Jalali M, Abedi D, Varshosaz J, Najjarzadeh M, Mirlohi M, Tavakoli N. Stability evaluation of freeze-dried Lactobacillus paracasei subsp. tolerance andLactobacillus delbrueckii subsp. bulgaricus in oral capsules. Research in Pharmaceutical Sciences. 2012;7(1):31-36.
- Clifford A. Adams. The probiotic paradox: live and dead cells are biological response modifiers. Nutr Res Rev. 2010 June; 23(1): 37–46
- Jasmeet Kataria, Nan Li, James L. Wynn, Josef Neu. Probiotic microbes: do they need to be alive to be beneficial? Nutr Rev. 2009 September; 67(9): 546–550