With the growing popularity and awareness of probiotic health benefits, product developers and consumers face a new issue: how to select the best probiotic strain for a specific consumer need. There are a number of key criteria for strain selection and product development.

Improving the Gut Microbiota

Bacteria can be found on our skin, and in the respiratory tract and the gastrointestinal (GI) tract. While the stomach has a relatively low number of bacteria due to its harsh acidic conditions, bacteria count and diversity increases from the small to the large intestine (colon). Bacteria can be classified in three categories: having health benefits, having no effect on health (benign), or having negative effects on health. To improve health, the goal is to improve the ratio of good to bad bacteria. Three different strategies are available: consuming live good bacteria (probiotics); consuming food for the good bacteria, allowing their number to grow (prebiotics); or reducing the amount of bad bacteria (bacteriophages). The most commonly used probiotics are species from the genera lactobacillus and bifidobacterium. Specific probiotic strains can be identified by genus, species and strain, e.g., Lactobacillus (genus) rhamnosus (species) GG (strain).

Functionally targeted probiotics open up new attractive markets beyond immunity and gut health. Probiotics’ established benefits are improving GI health and boosting the immune system; however, emerging research has probiotics flexing their muscles in sports nutrition (gut-muscle-axis), heart health (by managing blood lipid levels), allergies (improving gut permeability and immune response), cognition and mood (gut-brain-axis), and supporting a healthy inflammatory response.

Criteria for Probiotic Strain Selection

Health benefits of probiotics are strain specific. Structure/function claims require clinical substantiation in one human clinical trial, showing significant benefits over control, using a validated method, in a healthy population. When choosing the best probiotic strain for a product, start with identifying the target customers, consumer needs and marketing claims. People with an active lifestyle are twice as likely to consume a probiotic, so let’s take sports nutrition as an example. Find a probiotic strain directly linked to a sport specific benefit (e.g., increase athletic performance). Athletes have a greater microbiota diversity, which is linked to exercise and increased protein consumption, typically found in this group; therefore, select a strain that has actually been tested in athletes. And make sure to use the specific clinically validated strain at levels tested in the actual study.

Further, probiotics are live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. Keeping them alive, however, is a major problem resulting in short shelf lives of products, requiring overages (costs) and limiting delivery forms or potential combinations with other active ingredients that could be detrimental to the survival of the strains. In addition, probiotic efficacy is limited by gastric survival as only 10 to 25 percent survive passage through the stomach and upper intestine due to the harsh conditions caused by acidity, proteases or bile acid. Microencapsulation with controlled-release gastro-resistant vegetable oils protects strains during manufacturing of finished products, resulting in lower overages needed (cost savings), increased shelf life and formulation into unique delivery forms such as beverages. Clinical studies have shown the target release post-stomach increases gastroduodenal survival rate and subsequent colonization in comparison to uncoated strains. Encapsulated probiotics are suitable for use in capsules, tablets, sachets, stick packs, oil-based delivery systems, foods, instant drinks, chocolates, sprinkles and beverages.

What’s Next?

Standard testing of probiotic viability—the plate count technique—has numerous limitations, including the speed of analysis (requires incubation time of one or more days), underestimating bacterial number (bacteria may occur in chains and clumps), low viable counts (due to dormancy) and it only detects bacteria that are able to form colonies under the given growth conditions, not looking at metabolic activity. In addition, many enzymes, vitamins and flavorings can affect growth of the bacteria on agar plates, preventing an accurate analysis of viable bacteria in multi-ingredient probiotic products. Flow cytometry (cyto, meaning cell; and metry, meaning measure) is a rapid and sensitive technology that measures each cell individually. Flow cytometry allows reliability when distinguishing and quantitating live, injured and dead bacteria, even in a mixed population containing a range of bacterial types. Unlike typical CFU (colony-forming unit) plating methods, which sometimes have a 20 to 30 percent variation in test results—even at a single lab using one standard method—flow cytometric methods reduce variation by removing the human element of counting, and rely upon numbers generated by well-calibrated equipment. The future of probiotic testing may be found in flow cytometric methods, especially as the industry evolves with new and more complex delivery formulations.

Finally, products to improve the gut microbiota will evolve from simple pro- and prebiotic formulas to new categories such as synbiotics, postbiotics, fermented foods or even dead bacteria. Prebiotics are simply speaking fertilizer for the good bacteria. They can be used as “food" by the good bacteria and help them to multiply. Combinations of pro- and prebiotics can be called synbiotic, however, only if clinically shown that the co-administration of that specific prebiotic indeed increases the colonization of that specific probiotic. Postbiotics are the metabolic byproducts of probiotics. Short-chain fatty acids such as butyrate would be an example. Probiotics are, per definition, alive; however, recent studies with heat-killed bacteria showed that benefits on the immune system remain even with dead bacteria. While this is great news for shelf-life concerns of products as those bacteria are already dead, these so-called immunobiotics do have one big drawback—they can’t be called probiotic anymore.

Ralf Jäger, FISSN, CISSN, is the founder and managing member of INCRENOVO LLC. He is an inventor of functional foods and dietary supplements, and an expert in probiotics and sports nutrition. He has authored numerous peer-reviewed scientific papers, industry publications and mainstream media articles on sports nutrition; as well as brain, joint, heart and gut health. He studied at the California Institute of Technology and the University of Bonn, and began his career developing bioactive ingredients for a leading multinational billion dollar company.

NOTE: Ralf Jäger is speaking on the topic of “Finding the Right Ingredients to Meet Consumer Desires" at Probiotics Marketplace, a one-day immersive taking place April 27 in conjunction with Ingredient Marketplace. The event will include keynote panel discussion, poster presentations, networking and much more. For information or to register, visit marketplace.supplysideshow.com.