Women should be cautious about using the herbal remedy ginseng in the early stages of pregnancy, say researchers who have found the botanical to cause abnormalities in rat embryos.
One of the active chemicals in ginseng - ginsenoside Rb1 - is associated with significant development defects in animal embryos, report Hong Kong researchers in today's issue of the journal Human Reproduction.
Dr Louis Chan and colleagues at the Chinese University of Hong Kong Prince of Wales Hospital, Hong Kong, tested ginsenoside Rb1 in various concentrations on nine-day old rat embryos.
They found that embryos exposed to more than 30 micrograms per millilitre of ginsenoside Rb1 had significantly lower morphological scores, a test for development of the embryo's key organs.
At 30 micrograms the total morphological scores were significantly lower than the scores of the control group, which had not been exposed to gensinoside - 35 as opposed to 45 - and they had lower scores for heart, limbs, eye development and flexion. (The higher the score, the more normal is the development of the embryo.)
At the highest dose of 50 micrograms of ginsenoside Rb1 the total score fell to 28 and the embryos were also significantly shorter in body length and had fewer somites (muscle precursor cells).
"Our study has demonstrated that ginsenoside exerts a direct teratogenic effect on rat embryos: that is to say it is capable of causing malformations in rat embryos," said Dr Chan.
Ginseng is taken to enhance stamina and reduce feelings of fatigue and physical stress. It is also believed to have an anti-cancer function and has recently been found to normalise blood glucose levels, improving insulin sensitivity and reducing risk of obesity. However much less is known about the potential toxicity of the herbal and there are no data about its potential effect on the developing human foetus, said Dr Chan.
He cited a survey published in 2001 showing that over 9 per cent of pregnant women report using herbal supplements. In Asia up to 10 per cent have taken ginseng during pregnancy, he said.
The study showed that the reduction in morphological score was dependent on the dose, reported the researchers. It was therefore possible that lower concentrations of ginsenoside Rb1 might have caused less severe abnormalities that escaped detection by their research assessments, which were designed to study only gross abnormalities, they added.
Ginsenoside Rb1 is only one of the ginsenosides in commercially available ginseng. More than 20 have been identified and previous studies have shown that different ginsenosides might have different actions.
Further studies are needed to evaluate the potential teratogenic effects of other ginsenosides, said Dr Chan.
"Although results from animal teratogenicity studies may not reflect the circumstances in humans, our findings suggest that further investigations and monitoring of embryonic effects of ginsenoside on human pregnancy are warranted," he said.
"Before more information in humans becomes available, women should be cautious about using ginseng in the first three months of pregnancy and it is always advisable for pregnant women to consult their doctor before taking any herbal supplement," continued the researcher.
A recent survey by Chan found that 55 per cent of women in Hong Kong took traditional Chinese herbal medicine in pregnancy. Ginseng is currently one of the fastest growing herbs in the global nutraceutical market.