Problem cough? Nibble dried apricots. This fruit is packed with beta-carotene, which keeps the lining of the sinuses and throat healthy so germs can't get a toehold. Plus, beta-carotene boosts the production of virus-fighting T cells by 33 percent if you do get sick. Half a cup daily can quell a cough. Can't find dried apricots? Sweet potatoes, winter squash and carrots are also great sources.