May's Health Genie: Probiotics

Dear Health Genie,

I recently purchased an acidophilus probiotic supplement from the refrigerator in the wellness department. I assume I am supposed to refrigerate it at home. If warm temperatures are not good for the viability of the probiotic bacteria, then how is it going to live inside my GI tract?

Probiotic Pete

Dear Pete,

That contradiction does raise an interesting question. I should mention that not all probiotics require refrigeration. You can find probiotic supplements at City Market that are stabilized in order to eliminate this requirement. Also some species of probiotics are less temperature sensitive than others. You can find a list of probiotic products that do not require refrigeration on the door of the wellness refrigerator. The store refrigerates all probiotics because this does not hurt the viability of the product and it is convenient to keep all the probiotics together.

Lactobacillus acidophilus is the most common probiotic species. It is a component of almost every probiotic supplement. In the simplest supplements it is the only strain of bacteria. Refrigeration of this probiotic is practiced by manufacturers, health food stores and hospitals, unless the product has been processed to maintain non-refrigerated stability. Micro-organisms generally have a much shorter life cycles than macro-organisms. The lifespan depends on the conditions and the activity of the organism. Refrigeration is practiced to make these organisms remain dormant, somewhat like hibernation. At cooler temperatures the individual bacterium do not feed, metabolize, reproduce, or compete with each other. Human body temperature is the optimal temperature for Lactobacillus acidophilus. This is the best temperature for the population to grow, and if you are consuming foods that support healthy gastrointestinal flora, the short lifespan of the individual organisms will not matter, because the population will renew itself. Foods that support health GI flora are fibrous foods. Pectin and inulin are fibers thought to be particularly favored by healthy gut flora. Fruits, especially apples, are high in natural pectin. Jerusalem Artichokes and Elecampane herb contain inulin, which is rarer in foods. Some probiotic supplements include these and other nutrients to support the probiotics. Those nutrients are referred to a pre-biotics. Refrigeration can keep the probiotics from using up the pre-biotics. The term pre-biotic may or may not be used on the label. It is a relatively new term.

Now, what about L. acidophilus probiotics that are labeled as shelf stable at room temperature? Freeze drying is a common method that lengthens the shelf life even if the product is not consistently refrigerated. Removing moisture limits the metabolism of the probiotic until it is consumed. Probiotic pearls are probiotics encapsulated in a small hard shell that passes through the stomach into the intestines. These are typically shelf stable. It is the pH of the intestines that causes the shell to open. Other shelf stable probiotics use similar approaches, freeze drying and eliminating moisture to extend shelf life. Some practitioners suggest shelf stable and some suggest refrigerated probiotics. Which is best has not really been definitively determined. Following the manufacturer guidelines and using the item before the expiration date is important. Eating a diet high in fiber may help maximize benefits you experience from taking probiotics.


Good Luck,
The Health Genie



  • Grosso & Favaro-Trindade. 2004. Stability of Free and Immobilized Lactobacillus Acidophilus and Bifidobacterium Lactis in Acidified Milk and Immobilized B. Lactis in Yoghurt. Brazilian Journal of Micorbiology (2004) 35:151-156. ISSN 1517-8382
  • Haninik, RN, PHN, BSN. 2012. What Nurses Need to Know About Probiotics.  Accessed on 4/17/2012.


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