The Toxicity and Pathology of Selected Dietary Herbal Medicines

Abstract

Toxicity studies were conducted by the National Toxicology Program (NTP) to provide information on the potential for toxicity from long-term use of commonly used herbal medicines. Here, we review the findings from these NTP toxicology/carcinogenesis 2-year rodent studies of 7 commonly used herbs. In these studies, the individual herb or herbal product was administered to F344/N rats and B6C3F1 mice by oral administration for up to 2 years. The spectrum of carcinogenic responses ranged from no or equivocal evidence for carcinogenic activity (ginseng, milk thistle, and turmeric oleoresin) to a liver tumor response (ginkgo, goldenseal, kava), thyroid tumor response (ginkgo), or an intestinal tumor response (Aloe vera whole leaf nondecolorized extract). Different mechanisms may be involved in the occurrence of liver (ginkgo, goldenseal, and kava kava) and gastrointestinal toxicity (turmeric oleoresin and Aloe vera whole leaf nondecolorized extract), while the toxic lesion is the same. The results from these hazard identification toxicity/carcinogenesis studies along with those from ongoing National Institute of Health clinical trials of herbal medicines provide more complete information on the risks and benefits from herbal medicine use in the general population.

Ménière's Disease Treatment: A Patient-Centered Systematic Review

“…Although a small but statistically significant reduction of tinnitus was seen in patients taking ginkgo biloba with vascular dementia and Alzheimer's disease, there was no evidence that ginkgo biloba was effective in patients with a primary complaint of tinnitus [Hilton et al, 2013]. Ginkgo biloba has recently been proven to be an experimental carcinogen in bioassays on both mice and rats [Dunnick and Nyska, 2013]; therefore, the physician should carefully consider its side effects before using it, especially for long-term treatments.…”

The growing use of herbal medicines: issues relating to adverse reactions and challenges in monitoring safety

“…Therefore, cautious use had been advised in individuals or patients on anticoagulants therapy (Boullata and Nace, 2000). The ability of ginkgo to induce liver cancer in experimental model was reported recently and genotoxic mechanisms were suggested to play some role in the carcinogenic process (National Toxicology Program, 2012; Dunnick and Nyska, 2013). Similar observation was made in the thyroid gland and further studies are required to determine whether the mechanisms for the ginkgo-induced thyroid tumors are also found in humans (National Toxicology Program, 2012; Dunnick and Nyska, 2013).…”

“…Over 30 ginsenosides have been identified and these compounds are being investigated for their ability to inhibit cell proliferation, tumor cell invasion, and/or metastasis (He et al, 2011; Kim et al, 2012). Recently, the ability of ginsenosides to modulate signaling pathways involving cell cycle, inflammatory, or growth factor pathways, was demonstrated (Nag et al, 2012; Dunnick and Nyska, 2013). The leaf extracts of ginkgo had also been demonstrated to contain active compounds that had found usefulness in improving circulation and cognition (Boullata and Nace, 2000).…”

The potential of silymarin for the treatment of hepatic disorders

“…The large safety margin of silymarin was shown in the "milk thistle report NTP TR 565" [24,25]. The investigators gave feed containing 12,500, 25,000, or 50,000 parts per million (1.25 %, 2.5 %, or 5 %) of milk thistle extract to groups of 50 male and female rats and mice for two years.…”