The phrase "immune booster" refers to something that helps make your immune system stronger. It helps your body fight off illnesses and protects you from getting sick more easily. Full definition
We offer supplements that can act as immune boosters, joint support, daily supplements, with so much more. (animalelement.com)
High in antioxidants and vitamin C, grapes are a natural immune booster. (mindbodygreen.com)
It is ideal for active people before and after a workout, or just a real healthy refresher in summer, or a vitamin - bomb immune booster in winter. (contentednesscooking.com)