Most replayed moment: Can you really boost your immune system? | Professor Daniel Davis

The immune system functions as a complex, multifaceted defense mechanism that must distinguish between dangerous pathogens and the body's own healthy cells. Rather than seeking to "boost" immunity—a concept often promoted by misleading health claims—the goal is to maintain a balanced state that avoids overreaction, such as the allergic responses affecting two billion people globally. While the hygiene hypothesis suggests that early-life exposure to microbes may train the immune system, the specific mechanisms remain unclear and lack actionable interventions. Chronic stress significantly suppresses immune function by elevating cortisol, which diverts energy away from defense systems. Although practices like Tai Chi can lower stress hormones, evidence linking specific relaxation techniques to improved infection resistance remains limited. Ultimately, maintaining immune health relies on understanding these nuanced biological processes rather than relying on unproven supplements.