Black cohosh (referred to by the European Medicines Agency, or EMEA, as Cimicifugae racemosae rhizoma) is a member of the buttercup family, and is a perennial plant native to North America. It has a long history of use for by women to reduce menopausal symptoms such as hot flushes.
Historically it has been a popular alternative to hormone replacement therapy (HRT) in many countries including the UK, where it is estimated that 9 million days worth of black cohosh supplements were purchased in 2004.
Now, however, the MHRA said it wants warning labels to appear on black cohosh containing products. Its opinion was informed by the Commission on Human Medicines and the Herbal Medicines Advisory Committee, both of which have concluded that "the data underlines an association between black cohosh and risk of liver disease".
Details of the data reviewed by the two committees was not available prior to publication of NutraIngredients.com. But the EMEA's advice to doctors and patients, also published yesterday, was informed by a third evaluation, by the Committee on Herbal Medicinal Products (HMPC), which looked at 42 case reports of hepatoxicity.
Although it found that all the cases were poorly documented, it said that the connection "should be seen as a signal".
Patients are urged to stop taking black cohosh if they develop symptoms of liver damage, and to tell their doctor if they are already taking it. Health care professionals, meanwhile, are encouraged to ask patients about black cohosh use, and report suspected hepatic reactions to national adverse reaction reporting schemes.
A spokesperson for the EMEA told NutraIngredients.com that, as the body that evaluates medicines for human use, it does not have the jurisdiction to make warning labels on products mandatory. That she said is down to the regulatory bodies of individual countries.
Swedens' Medical Products Agency also issued a statement yesterday, pursuant to the EMEA opinion.
Barbro Gerden, a spokesperson for the agency and physician who has been involved in liver damage cases, said that warnings of the potential link between black cohosh and liver damage have been included on product information leaflets in Sweden for a number of years.
There are no plans to have warnings on the outside of products sold in Sweden at the present time, but discussions are underway on possibly strengthening the language used in the leaflets and requiring companies to describe the symptoms of liver damage.
The present furore in Europe comes five months after Australia's Therapeutic Goods Administration made warnings mandatory on black cohosh products sold within its bailiwick.
The proposed wording to appear on UK product packaging is: "Warning: In rare cases, black cohosh may cause liver problems. Consult your doctor if you already have liver disease or become unwell whilst using this product."
At this stage, it is not understood to be mandatory. Professor Philip Routledge, chair of the MHRA, said that the agency is "working with the herbal sector to ensure that labels of black cohosh products carry updated product warnings".
A meeting of the Health Food Manufacturers Association (HFMA) is being held tomorrow to discuss whether or not the proposed warning should be made mandatory for its members.
Rachel Abela, senior nutritionalist at Holland and Barrett, told NutraIngredients.com that her company is waiting on the outcome of the HFMA meeting before it determines its course of action - but it does tend to err on the side of caution.
Abela stressed that the most important part of the proposed statement are the words "in rare cases".
Professor Edzard Ernst, director of complementary medicine at the Peninsula Medical School, Universities of Exeter & Plymouth, said that only four of the case studies drawn upon by the investigation are such that any meaningful inferences can be drawn from them.
"I understand that regulators have to err on the safe side, but I wonder whether this is not some overreaction as black cohosh has been used for a long time," he said.
"It is a complex matter. One has a duty as a regulator or health care professional to not do any harm - that is the supreme law of medicine." But he added: "The warning may be throwing the baby out with the bathwater, as HRT is not very effecting and women are desperate for some means to control symptoms. There needs to be a careful balance."
Moreover, Professor Ernst said he was not aware of any specific research establishing a mechanism of action for black cohosh's effect on the liver.
As for whether the warnings will turn consumers off black cohosh products, Abela said she does not expect it will make much difference to people who are already committed to using natural products and complementary medicine regularly.
"It may affect people who are sceptical at the moment," she said.
If Holland and Barrett decides to use the warning it will begin to do so straight away, but the time it takes for new packaging to appear on shelves depends on individual store turnover. When mandatory labelling changes are introduced there is usually a six to 12 month window for compliance.