Postbiotics (heat-killed probiotics)

Tier 2 — promising · Gut · Immunity · Shelf-stable

Heat-killed bacterial preparations that provide immune and gut benefits without live organisms. The advantage is perfect shelf stability with no need for refrigeration. A 2024 review of 8 trials found heat-killed Lactobacillus preparations significantly reduce respiratory infection incidence and duration. The ISAPP scientific association formally defined postbiotics in 2021. Still an emerging category with less evidence than live probiotics.

Dose: 1–10 billion heat-killed cells/day (e.g., HK L-137 250 mg/day, ET-901 100 mg/day). Take any time of day with or without food — shelf-stable, no refrigeration needed.