Probiotics Storage: Should I Keep Probiotic Supplements under Refrigeration?
Demand is great among consumers for foods that are perceived as part of a healthy lifestyle. Expectations are high for foods that don’t just provide nutrients and satisfy hunger, but also prevent nutrition-related diseases and impart a sense of physical and mental well-being. The use of probiotics is one of the most promising areas for the development of what are being referred to as “functional foods.”
Probiotics are live bacteria or yeast that confer health benefits on the consumer. These foods help maintain and improve the balance of microorganisms in the gastrointestinal (GI) tract. There is still much work to be done in defining and understanding the roles of probiotics in health, but it is sufficiently established that they relieve some gastrointestinal illnesses.
Probiotics are also showing promise for lowering cholesterol and alleviating lactose intolerance. They are under investigation for immune system establishment, lowering high blood pressure, anticarcinogenic activity, relief of skin diseases, and more.
Storage Temperature of Probiotics and Refrigeration
To have positive effects on the consumer, there must be an adequate number of living organisms in a food product or supplement, at the time of consumption. There is no general agreement on the minimum numbers of live microorganisms, in millions and billions, per serving of a food or supplement. The number has to compensate for the probable decline in numbers of organisms during processing, storage, and passage through the acidic stomach and intestinal tract. Probiotic strains grow poorly in milk, so the final concentration of probiotics in yogurt and milk products is less than is indicated on the label, and entire loss of live organisms can occur with prolonged or improper storage.
Storage temperature is a key factor in maintaining the life of microorganisms. The products may be subject to “cold chain interruption” – periods of time during production, distribution, retailing and home storage when the best temperature is not maintained. The number of live microorganisms may drop so low, or to zero, that it renders the product ineffective as a probiotic source.
Scientific Findings regarding Refrigeration of Probiotics
There are few studies investigating such decline, but those which have been done show a significant loss in numbers of living organisms as the temperature and duration of cold chain interruptions increases. Different species and strains of probiotics have different rates of decline. The fastest decline occurs in yogurt at room temperature (not under refrigeration). Consistent storage at 5 degrees Celsius (41 degrees Fahrenheit) maintains viability of most probiotic organisms. At temperatures > 5 degrees C, the product becomes increasingly acidic, and compounds such as hydrogen peroxide and short chain fatty acids are formed, which are also detrimental to probiotics.
Of the probiotics tested in yogurt, at room temperature every 6 hours, only yogurt with L. rhamnosus still had living organisms at 24 hours. B. lactis Bb12 died fastest.
Although these findings occurred in yogurt it is reasonable to believe similar results will occur with probiotics in many forms – foods and supplements. More research is needed. The best, safest, message for consumers, from studies already done, is to refrigerate all forms of probiotics at all times. If the cold chain is interrupted, even for a few hours, assume that you are not getting as many living organisms as listed on the label.
If you’re looking for a basic background explanation about probiotics, you’re invited to read this article: What are Probiotics?
Probiotics and Refrigeration: References
- Tamine AY, Saarela M, et al. Production and maintenance of viability of probiotic microorganisms in dairy products. Probiotic Dairy Products, Blackwell Publishing, Ltd; 2005. pp39-72
- Scharl M, Ceisel S, et al. Dying in yogurt: the number of living bacteria in probiotic yogurt decreases under exposure to room temperature. Digestion. 2011; 83:13-17