You can find them in supplements, yogurt, kefir and even olives.
There are some suggestions mostly from lab studies and animal studies that probiotics can strengthen your immune system.
Look for products that contain live and active cultures. Probiotics shouldn't be used by everyone.
"The only people that need to be careful consuming the probiotics are people who have an immune system that's compromised, such as people with hiv or are receiving chemotherapy for cancer," says Doctor Sharon Bergquist or Emory School of Medicine.
Otherwise, experts consider probiotics to be safe with few side effects.