In a population-based observational study of 1,455 breast cancer patients in Shanghai, it was found that women who used ginseng before breast cancer diagnosis, or started taking the herb after diagnosis experienced benefits.
"When patients used ginseng prior to diagnosis, they tended to have higher survival," said lead researcher Xiao-Ou Shu, M.D., Ph.D. from Vanderbilt-Ingram Cancer Center. "Ginseng use after cancer diagnosis was related to improved quality of life."
Over one million women worldwide are diagnosed with breast cancer every year, with about 400,000 new cases in Europe. According to the European School of Oncology, the highest incidence rates are found in the Netherlands and the US. China has the lowest incidence and mortality rate of the disease.
The research, published recently in the American Journal of Epidemiology (Vol. 163, pp. 645-653), involved collecting data on ginseng use by person-to-person interviews to determine pre-diagnosis use, and then during follow-up interviews to ascertain post-diagnosis use. The type of ginseng used - white or red Asian ginseng (Panax ginseng C.A. Meyer), American ginseng (Panax quinquefolius L) - the nature of the product - powder, extract, tablet, capsule and so on - and the duration and frequency.
Prior to diagnosis, it was found that 398 women (27.4 per cent of the population) used ginseng on a regular basis. All of these women received at least one type of mainstream breast cancer treatment (chemotherapy, surgery, or radiotherapy).
Ginseng is typically taken to enhance stamina and reduce feelings of fatigue and physical stress. It is also believed to have an anti-cancer function and has been reported to normalise blood glucose levels, improve insulin sensitivity and reduce the risk of obesity.
The herb has been gaining popularity in Western societies, finding its way into, for example, energy drinks. In the US it is estimated to be the second top-selling herbal supplement, with $62m (€48.2m) in annual sales.
Despite such impressive sales figures, Shu said that there is still a lot of skepticism about herbal medicine. "That is why we are taking the observational approach at this time to see whether there is any efficacy. If so, we can go to the next phase… and eventually go to clinical trials," she said.
During the follow-up surveys, over an average of 4.8 years, the researchers found that number of ginseng users had jumped to 62.8 per cent of the 1,065 survivors.
It was found that women who had taken ginseng regularly pre-diagnosis had a higher overall survival rate than pre-diagnosis non-takers (88.6 versus 80 per cent), as well as a higher disease-free survival rate (83.8 versus 77.4 per cent, respectively).
Quality of life (QoL), measured using the General Quality of Life Inventory-74, improved amongst the women who started taking the herb after diagnosis. This is a measure of physical, social, psychological and material well-being.
"In our study, the average daily dose of ginseng was 1.3 grams of ginseng root material, and the average cumulative duration of use was 4.3 months per year. We found that ginseng use at this level significantly improved breast cancer survival and survivors QoL," concluded the researchers.
Both the WHO and the German Commission E have recommended daily safe doses of the herb as between one and two grams of ginseng root, which equates to between 200 and 600 milligrams of standardised extracts.
Although this observational study was not intended to elucidate the mechanism of protection, the researchers proposed that the compounds ginsenosides are behind the apparent benefits. Previous in vitro and animal studies have supported the proposal that these compounds have anti-cancer activity.
The study has several limitations, including the inability to measure survival rates of women who started taking the herb post-diagnosis. Also, no information on other complementary or alternative therapies was collected until the follow-up interviews. Finally, the study was based on the patients' recall of their ginseng habits and could be subject to under- or over-estimation.
"Thus caution is required in interpreting the results, and our findings need to be confirmed in more rigorous and randomised clinical trials," wrote the researchers.
This caution was echoed by Josephine Querido, from British charity, Cancer Research UK. Querido told NutraIngredients.com: "This Chinese study suggests that ginseng may have a beneficial effect on the quality of life of breast cancer patients and may also increase survival. But the overall body of research still provides no reliable scientific evidence that ginseng is effective in preventing or treating cancer in humans.
"If you are considering using complementary therapies, you should always discuss this with your GP to make sure it doesn't interfere with your current treatment," she said.
A recent review by Edzard Ernst, professor of complimentary and alternative medicine at the University of Exeter, concluded that the herb is generally well-tolerated, with adverse effects reported to be mild and reversible.
However, high doses of ginseng can lead to elevated blood pressure and dry eyes and throat.