RecruitingEarly Phase 1Dietary supplementResearching Economical Adjuvants to Cancer TherapyThe goal of this clinical trial is to learn if beta-glucan (a dietary fiber) improves the function of the immune system in adults. It will also tell the investigators if combining beta-glucan with single bouts of exercise provides additional benefit. The main questions it aims to answer are: 1. Does beta-glucan change the ability of immune cells to recognize cancer cells? 2. Does exercise change the type of immune cells in the blood? Researchers will compare beta-glucan to a placebo (a look-alike substance with no effect) to see if beta-glucan could improve immune function against cancer. Participants will: 1. Take beta-glucan or a placebo daily for 4 weeks. 2. Visit the laboratory for three exercise tests. 3. Provide blood samples so researchers can study immune system cells.