I'm not recommending the brand of tea in this picture, I got a kick out of the "American" branding and the chinese lettering.

Good stuff to know, especially with the coming of the cold and flu season.

In a recent study, cold-prone individuals who took two 200-milligram doses of a particular kind of ginseng every morning after breakfast with a glass of water caught fewer colds from November through February and experienced shorter and less severe colds than people who took a placebo. Researchers found that active compounds in ginseng boosted the participants' immune response. In a similar study, echinacea -- an herb credited with boosting immune function -- did not protect against colds. There are many different varieties of ginseng. In the study where ginseng boosted immune system function, the type of ginseng used was Panax quinquefolium. Another more common variety of ginseng, Asian Panax ginseng, was not tested in the study.

http://www.realage.com/ct/tips/2832

Panax quinquefolium is commonly known as "American Ginseng". A search in Google came up with a number of retailers who can provide supplements and teas.

I also found a study stating American ginseng may play a therapeutic role in creating a healthier circulatory system. The ginseng could make the cells in the blood vessels healthier. http://www.ncbi.nlm.nih.gov/pubmed/10592841