Fermented foods (kefir, L. reuteri yogurt, kimchi, sauerkraut, etc.) are, in my opinion, the best overall sources of probiotics. I prefer homemade versions so I can control the fermentation process and be sure they’re full of live microorganisms. That said, store-bought fermented foods from high-quality brands can be great options too, especially if you want to save time—though they usually cost more. Probiotic supplements vary a lot in quality and efficacy, but I do think they have a place—especially products like Visbiome, Akkermansia muciniphila, and Seed. At the end of the day, once you control for quality, strain specificity, and dose, the best probiotic is the one you actually take consistently.