LONDON, 3 September 2003 — Plants have played a key role in providing us with medicines for centuries, yet in the latter half of the 20th century, synthetic chemists have provided many of our new drugs.
In Britain plant-based remedies have been largely ignored, especially since 1945 and the introduction of the state-funded National Health Service (NHS), which has traditionally actively discouraged herbal remedies. Some sections of the medical profession still consider plants as yesterday’s medicines, but others are increasingly open-minded and are actively using advances in molecular biology and chemistry to re-evaluate the role plants could play in the health of people in the 21st century.
Reports last week that researchers are studying the use of sage in the treatment of Alzheimer’s disease illustrates some of that new interest in plants. Scientists at the universities of Newcastle and Northumbria in England discovered that people taking sage oil extract showed a marked improvement in their memory.
“This proves how valuable the work by old herbalists is, and they should not just be ignored because they were writing centuries ago,” said lead researcher Nicola Tildesley.
So should we all eat more sage to protect ourselves from Alzheimer’s? Sage is a name given to a whole range of species of salvia, and before we have people increasing their intake of sage and onion stuffing, they need to check which species of sage they have growing in the garden.
The species of sage used traditionally in Britain for improving the memory was salvia officinalis, but the essential oil of this species contains a compound called thujone, which is known to be a convulsant. Salvia lavandulaefolia is known as Spanish sage and is the species under investigation in Newcastle. It has low levels of this convulsant. And do not use wood sage, teucrium scorodonia, as this plant contains chemicals that could cause adverse reactions.
There is a difference in promoting the use of specific plants in your diet to increase your general health in contrast to the use of plants to treat specific diseases. We must take care when using traditional knowledge to promote the use of a plant for the treatment of a specific condition, since it does not always take into account the negative activity of some plants. However, traditional knowledge can assist us identify which plants should be selected for a study.
A range of plants are used traditionally in different societies to improve memory, and it is hoped that more research can be undertaken to evaluate whether they contain compounds that have the potential to be developed into drugs. Traditional Chinese medicine is a rich source of plants used to improve memory, such as the famous ginkgo tree, and certain species of angelica, biota, codonopsis, coptis, crocus and magnolia all have been used over the centuries to enhance memory, but whether they have potential in the treatment of Alzheimer’s is an open question. Even that soya sauce you add to your Chinese takeaway contains compounds called isoflavones that have been shown to improve memory.
Other species that warrant further research are less exotic. Melissa officinalis, known as balm, has been used in Europe to restore memory, and in Germany is used to treat insomnia.
At Kew Gardens, in London, we are attempting to maximize the use of traditional knowledge and state-of-the-art methods in plant chemistry to find compounds in plants that can assist us in the fight against drug resistant bacteria and fungi as well as diseases such as cancer, diabetes and AIDS. However, it takes many years from the discovery of a lead, as has occurred with the Newcastle research, to the delivery of an approved drug in a capsule.
In the meantime, maximize the use of culinary herbs that not only make food taste good but also do you good. The addition of many fresh common herbs such as thyme, lavender and mint to our diet increases the diversity of compounds that have different forms of antioxidants and heath-promoting actions. For example, rosmarinic acid in rosemary is said to increase our resistance to infections. But before plunder your herb garden, check that you can distinguish among the different species.
