Here are some answers
based on science.

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

Microencapsulation is the preferred
method for bacterial protection.

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⁾.

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.