What naturally kills bacteria in the body?

What naturally kills bacteria in the body is primarily your immune system, which has multiple layers of defense that work constantly without medicines. First, white blood cells like neutrophils and macrophages engulf and digest bacteria through phagocytosis, literally eating them. Natural killer cells destroy infected cells. The complement system, a group of proteins in blood, marks bacteria for destruction and punches holes in their walls. Antibodies produced by B cells tag bacteria for removal and neutralize toxins. Beyond immune cells, your body produces natural antimicrobial substances, such as lysozyme in tears, saliva, and mucus that breaks bacterial cell walls, defensins and cathelicidins in skin and gut that kill bacteria, and stomach acid with pH 1.5 to 3.5 that kills most ingested bacteria. Beneficial gut bacteria also compete with harmful bacteria and produce substances that inhibit them. Some foods contain mild natural antimicrobials, such as garlic contains allicin, honey produces hydrogen peroxide, and cranberry prevents bacteria from sticking to bladder walls, but these are not strong enough to cure serious infections alone and should not replace antibiotics. Fever helps kill bacteria because many bacteria grow best at normal body temperature and immune cells work better at slightly higher temperatures. Good sleep, hydration, balanced nutrition with protein and zinc, and good indoor air quality support natural killing. For serious bacterial infections, you still need medical antibiotics because natural defenses can be overwhelmed.