American ginseng (Panax quinquefolius) is a North American relative of Asian ginseng, sold for fatigue, immunity and blood sugar. It has a few larger trials, including a 364-person trial in cancer-related fatigue.
Also known as: Panax quinquefolius, North American ginseng, Wisconsin ginseng, CVT-E002.
Trials used 2,000 mg a day for 8 weeks for fatigue (Barton 2013), 2 capsules a day of an extract for 4 months for colds (Predy 2005), and a single 3 g dose before a glucose drink (Vuksan 2000). These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
What studies show: in a trial of 364 fatigued cancer survivors, fatigue scores improved more with 2,000 mg a day of American ginseng than with placebo at 8 weeks, but not significantly at 4 weeks, with more benefit in people still in cancer treatment (Barton 2013). In a 4-month trial in adults who had at least 2 colds the year before, people on an American ginseng extract had fewer colds (0.68 versus 0.93 per person) and fewer days with symptoms (Predy 2005). In a small study, 3 g taken before a glucose drink lowered the blood sugar rise by about 18% to 22% (Vuksan 2000).
Safety: the fatigue trial found no difference in side effects from placebo (Barton 2013). In a trial in 20 healthy adults, American ginseng lowered warfarin's blood levels and its effect on INR (Yuan 2004). The authors of the blood sugar study note that people without diabetes may want to take it with a meal to avoid unintended low blood sugar (Vuksan 2000).
We could not find a single published half-life or time to peak for American ginseng that applies to a supplement dose, so we do not list one. Plant extracts are mixtures of many compounds, so no single figure would describe them.
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