WEST LAFAYETTE, Ind. -- What do you get when you buy a bottle of the herbal cold remedy echinacea?
You really don't know what you're getting, says James Simon, professor of horticulture and co-director of Purdue's New Crops Center, because of the lack of consistency in herbs and medicinal plants.
Echinacea, for example, is used by many people to combat cold symptoms. But according to Simon, there are two different echinacea plants -- Echinacea purpuea and Echinacea angustifolia -- and most product labels give little information about which plant was used in the herbal remedy.
"Both plants produce the compound that has the biological activity, but in different amounts," he says. "Regardless of which species is used in a product, it's the responsibility of the manufacturers to come up with a mix that gives consumers the amount of the active ingredient that they need. But the amount of the active ingredient that is in the product isn't put on the label."
Echinacea is just one of many examples of the uncertainty that exists with herbal remedies and functional foods, Simon says.
"There can be differences in the biological actions of medicinal plants, depending on environmental and genetic differences," he says. "The way that a plant is harvested, and when it is harvested, can make a difference in the quality. It requires a good understanding of the plants and the environment to assess that it is high quality."
The natural variation of plants within a species can have a tremendous effect on the quality of the herbal remedy. "Some wild plants may have very high amounts, and some plants may be devoid of it. Anytime you have a natural product, there is going to be a lot of biological diversity," Simon says.
The way to control the variations in quality and to instill consumer confidence is to demystify herbal products through scientific research, he says.
"Only one-third of the population has tried using medicinal plants, and it's going to be hard to convince the other two-thirds of the population unless you can back up the health claims with good science," he says.
Simon advocates greater study on the pharmacognosy, or description of the pharmaceutical properties, of the plants and that this information be made available to doctors, nurses and pharmacists. "Sometimes good information such as this is known, but people in the medical profession don't use them because they don't know much about these plants," Simon says.
More often, however, the scientific information on how the herbal remedies work isn't available. "Too often when these companies say they invest so much in research, what they are talking about is marketing research," Simon says. "Having said that, there has been a change over the past five years. Research is beginning to test for significant biological actions. Consumer demands and expectations have forced companies to change the way they do business."
If such research is conducted, it won't be easy, because many medicinal plants contain several compounds that may have medicinal value.
"Often, people talk about just one compound in a plant, but there may be several compounds, perhaps working together, that give a plant its biological effect," Simon says. "For example, feverfew, a plant that historically was used to reduce fevers, is now often used as a remedy for migraine headaches. The compound that has been identified as giving it this effect is parthenolide. But parthenolide itself doesn't appear to have the same effect as the feverfew herb."
Because of this, rather than trying to create a plant that produces more of one active compound, agriculturists interested in improving medicinal plants might need to work on enhancing the biological activity of the entire plant, a process that would require sophisticated animal and humans tests.
"This is a much more daunting task," Simon says.
Because the environment and harvesting methods can have such an effect on the medicinal quality of the final product, Simon says that economic opportunities for growing medicinal plants can be very good for some farmers.
"Ultimately there will be economic opportunity for farmers to grow these highly specialized crops, such as cone flower for echinacea," Simon says. "The opportunities will be limited, but the market will be there. These crops won't replace cash crops such as corn and soybeans, but for a tobacco farmer or a vegetable farmer, who is used to growing high-value, high-labor crops on a small acreage, these crops will be attractive." swt/Simon.medicinal
Writer: Steve Tally, (765) 494-9809, tally@aes.purdue.edu
Related Web sites: Simon's professional home page: http://www.hort.purdue.edu/hort/people/faculty/simon.html