Mushrooms have been used for health for thousands of years and contain special compounds that help boost the immune system and fight cancer. Scientists have identified several key active ingredients in mushrooms like polysaccharides and proteins that can activate immune cells and reduce tumors. Some mushroom products like lentinan from shiitake mushrooms have already been approved as cancer treatments in Japan. While most evidence comes from lab studies, ongoing research suggests mushroom-based medicines could become important therapeutic options.