Asparagus
Asparagus is a Superfood for your Immunity because a serving (5 spears - 93g) provides at least 10% of your daily value for vitamins A and C plus it contains antioxidants in the form of polyphenolic phytochemicals -- nutrients that help support a healthy immune system. Vitamin C is essential for the normal functioning of white blood cells by protecting them during the free radical mediated cell destruction of invading bacteria and viruses that challenge the immune system. One recent Japanese study demonstrated that the risk of developing 3 or more colds in a 5 year period was decreased by 66% with higher daily vitamin C intake, although no effect on duration or severity was observed. Another study observed a consistent halving in the duration of colds experienced by runners, skiers and soldiers. While vitamin C receives most of the attention for its role in fighting colds, vitamin A is the unsung hero of immune function. Some researchers even call vitamin A the 'anti-infective' vitamin because it helps support the body's first line of immune defense: the maintenance of skin and mucosal cells lining the airways, urinary and digestive tracts. In addition its metabolites also help maintain active levels of natural 'killer' cells which have antiviral and anti-tumor properties. Vitamin A also plays an important role in the development of a specific type of white blood cell, called a T-lymphocyte, which research shows are important in defending the body against viruses and bacteria. The antioxidant phytochemicals present in cooked asparagus as evidenced by an ORAC score of 1,529, may also play a key role in immune function. The decline in immune function seen in extreme athletes (marathon runners) and soldiers after physical exertion is similar to that seen in old age. North Carolinas' Appalachian State University researchers suggest polyphenols like quercetin can significantly reduce infection rates in such populations therefore improving a weakened immune function.