Probiotics are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. Most probiotics contain beneficial bacteria.

There are four major categories of probiotics that are commercially available:

1. Lactobacillus and Bifidobacterium (many species)
2. Saccharomyces boulardii (probiotic yeast)
3. E. Coli Nissle 1917 (probiotic E. Coli)
4. Soil-based organisms (various species of bacteria)

Other species and strains are currently being studied for their potential use as probiotics.

Under normal conditions, probiotics do not “re-seed” the gut with healthy microbes. Instead, they confer benefits during transit through the GI tract by influencing digestion, immune function, or gene expression.

Probiotics have been well-studied and shown to be beneficial in hundreds of randomized controlled trials. However, the benefits are strain-specific, and it is important to select strains that have demonstrated safety and efficacy in human clinical trials.

For more on probiotics, check out these articles: