Dr Howes from Kew Gardens shares insights on her research around plants that protect the mind.
1. Why did you choose the plants you chose to research for neurodegeneration?
My research has focused on edible plants because uncovering which edible plants could delay or prevent cognitive decline through the diet could provide more accessible and widespread benefits to people. Furthermore, emerging scientific evidence has suggested that certain dietary plants may have positive effects on cognitive functions, in addition to biological activities relevant to alleviating cognitive decline in ageing or dementia. These plants include sage, rosemary and lemon balm.
2. What are some of the challenges you face with herbal research?
One of the main challenges of research on plants is that their chemical profiles, and therefore their biological activities, can vary considerably, even within the same plant species. This may be due to various factors such as where the plant was grown and the associated environmental conditions, the age of the plant, the part of the plant, when the plant material was harvested, genetic factors, and how the plant is processed or prepared after harvesting. The complex and often varied mixtures of chemicals that can occur in plants can introduce challenges for their quality control, and when assessing which chemical or chemicals are the active constituents of a herbal plant.
3. What were the most interesting insights you found with your research on plants and neurodegeneration?
Plants can produce a diverse range of many different classes or types of chemicals. One of the most interesting insights from my research is that the chemical structures of plant chemicals that have biological activities relevant to brain or cognitive functions are highly diverse and occur in a range of different edible plants. This is particularly interesting as this chemical diversity could provide the basis for diets that could incorporate certain edible plants, with the aim of reducing potential cognitive decline.
4. Do you think herbs could potentially have a preventative role to play in neurodegeneration?
A number of herbs, including those that cross the blurred boundaries of being used for both culinary purposes as part of the diet, and as medicinal plants, have shown biological activities to suggest they may have effects that could help prevent neurodegeneration and cognitive decline. However, most of these studies are from laboratory research only and much more research is needed to evaluate whether any benefits actually occur in people. More comprehensive scientific research is needed, including robust clinical trials in people, to understand if or how certain plants may be useful to prevent or delay neurodegeneration or cognitive decline.
Bibliography of research
- Perry NSL, Menzies R, Hodgson F, et al. A randomised double-blind placebo-controlled pilot trial of a combined extract of sage, rosemary and melissa, traditional herbal medicines, on the enhancement of memory in normal healthy subjects, including influence of age. Phytomedicine (Stuttgart). 2018;39:42-48. doi:10.1016/j.phymed.2017.08.015
- CantwellâJones A, Ball JC, Collar DC, et al. Global plant diversity as a reservoir of micronutrients for humanity. Nature Plants (Online). 2022;8(3):225-232. doi:10.1038/s41477-022-01100-6
- Howes MR. The evolution of anticancer drug discovery from plants. The Lancet Oncology. 2018;19(3):293-294. doi:10.1016/s1470-2045(18)30136-0
- Williams PG, Sorribas A, Howes MR. Natural products as a source of Alzheimerâs drug leads. Natural Product Reports. 2011;28(1):48-77. doi:10.1039/c0np00027b
