Why low temp matters for probiotics

Refrigerated probiotics generally contain a wider range of live bacterial strains.
The stability and diversity of refrigerated products prevent the overgrowth of dominant strains.
Refrigeration maintains both the viability and vitality of the strains, allowing colonisation and reproduction of the live bacteria.
Refrigeration is key for preserving diversity and the proportion of strains in multi-strain probiotics which are key to the synergistic action of the De Simone Formulation blend.
Processes like encapsulation do protect the bacteria but impact the properties and metabolic activities of the probiotic strains
Low-concentration non refrigerated probiotics can use overage to make up for the natural loss of viability during shelf life, it doesn’t necessarily mean that it is stable at room temperature.

An article supported
by 13 scientific studies

Here are some answers
based on science.

The World Health Organization defines probiotics as live microorganisms that confer a health benefit to the host when consumed in adequate amounts. The quality and effectiveness of each product depend, among other things, on the manufacturing processes, the strains and viability of dosed bacteria, and their ability to survive the physiological conditions within the gastrointestinal (GI) tract. There are no regulations governing the production of probiotics, also contributing to the differences in quality and efficacy. Regardless of the quality of the probiotics, the safety and efficacy can only be confirmed by adequate clinical studies.

Probiotics can be refrigerated or non-refrigerated, but…

Refrigerated probiotics generally contain a wider range of live bacterial strains and species at higher concentrations than non-refrigerated products. This allows to maintain the same proportions of the strains within the blend and can improve their effectiveness in colonising the gut and modulating the microbiome.

Traditionally, the goal has been to keep microorganisms alive until consumption. However, the viability of these bacteria depends upon many factors, such as manufacturing processes, competing bacteria, and toxicity of metabolites. Scarce scientific evidence currently suggests that once ingested, molecules and surface components secreted by bacteria are sufficient to mediate the cross-talk between the host and probiotic cells.

The International Scientific Association for Probiotics and Prebiotics have produced evidence-based recommendations on the safety of these products in different populations. The effectiveness of probiotics may vary depending on treatment, disease, and strains that make up the probiotic (1).

It is essential to choose a reputable probiotic supplement that matches the individual’s needs and follow the manufacturer’s instructions for storage and usage to maximise the benefit (2).

The beneficial effect of a probiotic could depend on the administered dose

A certain amount of viable cells seem to be necessary to obtain different effects such as immuno-modulation (by surface components or secreted compounds which can stimulate immune defensive mechanism or suppressed exacerbated inflammation induced by infectious or pathogenic agents) (3-4), production of antagonistic substances (organic acids, bacteriocins), competition for nutrients or adhesion sites, and modulation of toxin action or production (proteolytic destruction of toxin molecule or toxin receptor, toxin fixation on probiotic surface (5)).

Refrigeration slows down the metabolic activity of the microorganisms, preventing their growth and multiplication. Thus, refrigeration leads to higher viability and vitality than ambient conditions (6). In general, low temperatures and low humidity result in higher survival rates during the storage of all probiotics (7). Once ingested, a higher percentage of live microorganisms tend to survive in transit through the gastrointestinal tract in refrigerated products; therefore, more bacteria are present to exert a beneficial effect.

The cold chain from the production line to the consumer can be complicated, but it has advantages.

Microencapsulation is the preferred
method for bacterial protection.

Microencapsulation of probiotics protects

The type and proportion of microorganisms in the gut determine the energy balance of the host. The diversity of strains in our probiotics gives a cross-stimulation effect that allows other bacteria to grow once ingested, releasing a range of metabolites. These metabolites, in turn, stimulate the production of short-chain fatty acids (SCFAs), a dominant energy source (8). While single-strain probiotics benefit health, combining several microbial strains provides additive effects (9), one of which is a synergistic participation in metabolic processes.

The reasons for better efficacy of multistrain probiotic preparations seemingly derive from the large individual interrelations between microbiota and health markers apparent also in case of GI diseases (10).

Many probiotics are now formulated with protectants that encapsulate the bacteria, maintaining viability at room temperature. Microencapsulation is the preferred method for bacterial protection. However, the effects of microencapsulation on the microorganisms should be considered (11). Microencapsulation of probiotics protects them from the low pH, bile salts, and other constituent products they encounter during GI transit. Indeed, some encapsulation methods may disrupt the fragile bacterial membrane, causing toxicity and death of the bacteria (12).

Refrigerated and non-refrigerated probiotics have higher concentration of bacteria at manufacturing than is stated on the packaging, why?

This ‘overage’ guarantees the declared colony forming units (CFU) at the expiry date to make up for the natural loss of live bacteria during the shelf life (13). Low concentration probiotics can more easily begin with two to four times the declared concentration with fairly low economic impact. The loss of viability will be more significant in non-refrigerated products with the consequence of ingesting a certain quantity of dead bacteria.

In the final marketed product, a probiotic formulation should be ultimately based on the dose–effect relationships established in the hosts, which can depend on strain viability during the product shelflife and on its survival and pharmacokinetics in the gastrointestinal tract (5).

Clinical studies are the key to confirming a probiotic’s quality, safety and efficacy, and they should be conducted with the exact marketed formulation. The consumer should be more clearly informed whether the product they find on the shelf is the exact same product evaluated in clinical studies.


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  2. Marlicz W, Skonieczna-Żydecka K, Krynicka P, Łoniewski I, Rydzewska G. (2021) Probiotics in irritable bowel syndrome – is the quest for the right strain over? Rapid review of existing guidelines and recommendations. Prz Gastroenterol. 16: (4) 369-82. 10.5114/pg.2021.111766. PMC8690954.
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  7. Wendel U. (2021) Assessing Viability and Stress Tolerance of Probiotics-A Review. Front Microbiol. 12: 818468. 10.3389/fmicb.2021.818468. PMC8829321.
  8. Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ, et al. (2017) Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 14: (8) 491-502. 10.1038/nrgastro.2017.75.
  9. Kwoji ID, Aiyegoro OA, Okpeku M, Adeleke MA. (2021) Multi-Strain Probiotics: Synergy among Isolates Enhances Biological Activities. Biology (Basel). 10: (4): 10.3390/biology10040322. PMC8070017.
  10. Mikelsaar M, Lazar V, Onderdonk AB and Donelli G, Do probiotic preparations for humans really have efficacy? Microbial Ecology in Health & Disease 2011, 22: 10128 – DOI: 10.3402/mehd.v22i0.10128
  11. Sbehat M, Mauriello G, Altamimi M. (2022) Microencapsulation of Probiotics for Food Functionalization: An Update on Literature Reviews. Microorganisms. 10: (10): 10.3390/microorganisms10101948. PMC9610121.
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