Vitamin C is crucial for a healthy immune system function. It supports the production and function of white blood cells, which are essential for fighting infections. Additionally, vitamin C acts as an antioxidant, protecting cells from oxidative stress and enhancing overall immune responses. Sources of vitamin C include citrus fruits like oranges, strawberries, and kiwis, alongside vegetables such as bell peppers and broccoli. Maintaining adequate levels of this vitamin is important for overall health, particularly during flu seasons or when undergoing physical stress, as it helps bolster the body's defense mechanisms.