“Most probiotics” can mean either (1) fermented foods that naturally contain live microbes, or (2) standardized probiotic supplements with defined strains and doses. Fermented foods like kefir, yogurt, certain cheeses, kombucha, and fermented vegetables (e.g., sauerkraut/kimchi) can be good sources, but microbial content varies greatly with processing, heat treatment, storage, and shelf time. Pasteurized fermented products may contain few or no live organisms. Supplements can offer clearer dose consistency—yet only if strain identification, CFU, and quality control are reliable. In practice, the most sustainable approach is diversity: regular fermented foods plus a fiber-rich diet (prebiotics) and adequate overall nutrition. Also, “more” is not always better; rapid fermentation can increase bloating for some people, so gradual introduction and individualized tolerance matter.