Top 10 Worst Things for Your Immune System By the editors of Prevention.com 1. You Avoid the Water Cooler Friendship may be Miracle-Gro(plant food) for your immune system. Research shows that the fewer human connections we have at home, at work, and in the community, the likelier we are to get sick, flood our brains with anxiety-causing chemicals, and live shorter lives than our more sociable p..