A new system has been devised to rate the efficacy of herbal medicines according to published evidence. The Natural Standard Research Collaboration group in Cambridge, Mass. provides reviews of data on herbal medicines and alternative practices, evidence-based information on safe and drug-herb interactions, and an efficacy rating for herbal treatments.
Based on evidence and safety, the rating provides a National Standard Grade for each clinical application.
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Definitive evidence of benefit |
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Quality evidence of benefit that is not definitive, with positive animal data |
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Data less than rigorous (such as in small trials or case-cohort studies), conflicting or derived only from laboratory or animal studies |
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Fair evidence showing no effect. |
The 10 most popular herbs were given the following ratings:
Herb | Rating |
Black cohosh | Menopausal symptoms - B; Joint pains - C |
Evening primrose oil | Atopic dermatitis - B; preeclampsia, Raynaud's, asthma - C or D |
Saw
palmetto |
Benign prostatic hypertrophy - A; male pattern baldness and underactive bladder - C |
Valerian | Insomnia - B; anxiety disorder - C; sedation - D. |
St. John's wort | Severe depression B or C; mild to moderate depression - A; anxiety disorder, obsessive-compulsive disorder, perimenopausal symptoms and premenstrual syndrome -C |
Echinacea |
Treating upper respiratory infections - B; prevention of upper respiratory infections , radiation-induced neutropenia, cancer - C; genital herpes - D |
Bilberry |
Vascular conditions, eye disease - C; improvement of night vision - D |
Cranberry |
Prevention of urinary tract infection - B; antiviral, antioxidant, antifungal, cancer prevention - C; treatment of urinary tract infection, kidney stones, dental plaque - C |
Wild yam | Menopausal symptoms, hyperlipidemia - C |
Ginger |
Chemotherapy-induced and pregnancy-associated nausea - B; post-surgical nausea and motion sickness - C; rheumatoid arthritis, osteoarthritis, arthralgia and muscle pain - C. |