As if you need another reason to avoid double cheeseburgers: Scientists have found that mice fed a high-fat diet containing relatively large amounts of lard have significantly reduced immunity and higher mortality rates when compared to mice fed diets rich in polyunsaturated fats from fish. Could this be why Okinawa, Sardinia, and Nova Scotia (islands where presumably populations eat more fish) boast a higher percentage of longevity?

Refined sugar also tops the list of immune-suppressing foods. Here's what you should eat to boost your immunity.