1.   Health food stores promote all manner of herbs to prevent colds.

2.   Vitamin C is popularly believed to prevent colds.

3.   Another herb, astragalus, is less trendy but more effective at actually preventing colds.

4.   Can vitamin C prevent colds?

5.   Consider, for instance, the TV show that said cocoa powder can help prevent colds.

6.   Some of these substances, called phytochemicals in the laboratory, may eventually be shown to prevent colds, while others are being tested as treatments once symptoms start.

7.   Echinacea, an extract from the coneflower, was no better at preventing colds than a placebo, the study said.