 Downy Rinse and Refresh removes more odor in one wash than the leading value detergent in three washes. Find it wherever you buy laundry products. All righty, what does the ultimate immune system diet look like? Researchers from UCLA's Center for Human Nutrition recently came up with some guidelines. First, eat at least two plant-based meals a day with as many different fresh fruits and vegetables as possible. Researchers say fresh produce contains prebiotics, which play a role in activating the T-cells that are like first responders in your immune system.