The 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.

This investigation is a randomized, placebo-controlled trial seeking to determine the extent to which acute exercise and dietary β-glucan supplementation can augment immune responses against cancer. The investigators will mechanistically determine the receptor-ligand interactions between effector lymphocytes and target cancer cells, as well as assess multiple immunotherapies alongside the intervention (e.g., ipilimumab, pembrolizumab, monalizumab). Incorporating lifestyle medicine is well known to improve patient quality of life, and early evidence suggests it may favorably impact overall survival. It is crucial that the investigators harness the immunological potential of lifestyle interventions to broadly improve immunotherapy effectiveness.

Inclusion Criteria:

• Physically fit enough to engage in maximal exercise.

Exclusion Criteria:

• BMI > 40 kg/m2
• Stage 2 hypertension (140/90 mmHg)
• Type I or II diabetes
• Autoimmune diseases
• Overt cardiovascular, respiratory, or neurological disease (e.g., previous heart attack, pacemaker, heart failure, asthma)
• Hormone replacement therapy (e.g., androgens, estrogens)
• Daily medication usage that may affect immune function (e.g., beta blockers, NSAIDs, corticosteroids, allergy medications)
• Current antibiotic use
• Heavy alcohol usage (>2 drinks per day)
• Tobacco use within the last 6 months
• Adults unable to consent
• Individuals who are not yet adults (infants, children, teenagers)
• Self-reported pregnancy
• Prisoners