Probiotics are live microorganisms, such as certain bacteria or yeasts, that can provide health benefits when consumed in sufficient quantities. Unlike prebiotics, which are fibers or nutrients that feed these microorganisms, probiotics themselves are the active components. These beneficial microbes are often found in foods like yogurt or in dietary supplements. However, not all probiotics are the same—most commercial products contain only a few distinct strains, each with its own potential benefits. Some of the most commonly studied strains include Lactobacillus plantarum, Lactobacillus rhamnosus GG, Bifidobacterium longum 35624, and Saccharomyces boulardii. Even within the same species, different strains can have varying effects, so it is important for products to clearly list the specific strains they contain, not just the general species. The effectiveness of a probiotic depends not only on the strain but also on the number of live microorganisms it contains. This number is measured in Colony Forming Units (CFU), which represents the number of viable microorganisms in the product. However, a higher CFU count does not always mean a more effective product. For example, the Canadian Digestive Health Foundation suggests that 100 million CFU might be more effective for certain conditions than 10 billion CFU, especially when supported by clinical research. Therefore, it is crucial that the product’s labeling includes the specific strains, the CFU count, and the intended use, so consumers can make informed choices based on scientific evidence. To ensure a probiotic is effective and safe, it should be supported by randomized clinical studies that test the specific strain for the intended use and target population—such as children, adults, or individuals with digestive issues. Consumers should look for products that clearly identify the strains, their CFU levels, and other ingredients, as well as the storage conditions. Proper storage is essential because factors like humidity, temperature, and oxygen can affect the viability of the microorganisms. Some supplements use gastric-resistant capsules to protect the microbes from stomach acid, while others combine probiotics with prebiotics, which may help support the growth of the beneficial bacteria. In addition to clear labeling, certifications like the V-Label can offer more transparency about a product’s composition, especially for vegetarian or vegan consumers. However, such certifications do not guarantee the effectiveness of the probiotic itself. Ultimately, a good probiotic is defined not by the number of billions of CFU listed in bold, but by the accuracy of its labeling, the scientific backing of its strains, and the clarity of its intended benefits. Consumers are encouraged to choose products that are well-researched, transparent, and tailored to their specific health goals.