Wednesday, September 17, 2008

Forest Pharmacy

A discussion of herbal medicine and supplements can be a dangerous minefield to cross. People tend to entrench themselves either on the side of “real” medicine where human ingenuity is the driving force behind pharmaceutical innovation, or with those that view human-manufactured drugs with cynicism seeing natural products, unspoiled by human alteration, as the main avenue to maintaining health.

As is nearly always the case when people are neatly divided into two camps, reality lies somewhere in the middle and our local forests are an example of this. Though rife with plants with medicinal qualities, not all plants of Eastern Townships are directly edible and require transformation in a laboratory to enhance their effectiveness and avoid toxic reactions and unwelcome side-effects. There is no need to go thumbing through a medical textbook to convince yourself of this; a short, guided hike can demonstrate both that medicine is often times a wonderful combination of natural diversity and human ingenuity and that tropical forests are not the only places that contain exciting medicine. With the right knowledge, a hike in the Townships can be just as much like foraging through a pharmacy as it is a walk in the woods.

Mary Poppins would be delighted with the first forest medicine we’ll explore as it comes with a spoonful of sugar. It’s difficult to hike in the Townships without crossing paths with blackberries, blueberries, raspberries, currants, cherries, strawberries or the stray, abandoned apple orchard. Aside from the fact that they all make delicious pies, these fruits also contain a compound called quercetin giving them colour and many potential health benefits. By blocking histamines, it can provide allergy relief to sufferers and it has anti-inflammatory properties that can reduce swelling for those with arthritis. It’s also an antioxidant which means it can lower the level of “bad” cholesterol in your blood and protect your DNA from damage caused by free-radicals. It can even be used in treating more serious illnesses like cancerous skin and prostate tumours. More recently, it has demonstrated the ability to reduce mice’s susceptibility to the flu though whether it will have this same property in humans is yet to be determined. Much of the benefit of quercetin can be obtained directly from nature without transformation. However, fruits only contain quercetin in small amounts so for it to have any effect you need more than a couple berries; a regular diet of these fruits as well as vegetables high in quercetin (red onions, parsley, olives) can help reap its benefits.

The Canadian Yew is an example of medicinal plant you won’t want to enjoy directly from nature. Though its bright red fruit is the only non-toxic part of this sprawling, evergreen shrub (caution: the seed inside the fruit is toxic which I is why I just steer clear of eating any part of it) it is the bark that contains the medicine. Its bark contains paclitaxel which is extracted and used as a treatment that inhibits the growth of ovarian and breast cancers cells. Originally, paclitaxel was harvested from the bark of the Pacific Yew tree but the amount of bark it took to make the drug were prohibitive so now it is simply synthesized in a laboratory from a more common compound found in the needles.

Another medicinal bark is that of the willow tree which is the source of an anti-inflammatory that can also reduce fevers. In use for millennia, the “father of medicine” himself, Hippocrates, described the effects of the bark in the 5th century BC. What he was observing was the effects of salicylic acid, which is only a short chemical reaction away from aspirin. Salicylic acid has similar medicinal properties to aspirin but causes more digestive upset which is the reason we use the over the counter version instead. Aspirin itself, developed in the late 19th century, was derived from another common plant to the Townships: meadowsweet. A relative of the rose with small white or pink flowers, it contains methyl salicylate, another precursor of aspirin. Contrary to the willow tree, the entire meadowsweet plant can be used for medicinal purposes but its high potency makes this plant risky to use. If you have a headache, you’re better off getting your aspirin from the pharmacy rather than from this plant.

Although we think of vineyards more as source of wine than of medicine grapes – both the wild river bank grape abundant in the Townships or its cultivated cousin – are a healthy source of antioxidants, quercetin and, most notably, resveratrol. It can lengthen the life of certain organisms including yeast, worms, a short lived species of fish and even mice causing wine and resveratrol to make headlines. Unfortunately, by the time you’ve had enough wine for it to have effect, you would have a failing liver to worry about.

Incase I got your hopes up with the life-lengthening potential of resveratrol and now you’re feeling a little blue, try some St-John’s Wort. This little yellow flower has been shown to be just as effective as commercial antidepressants for treating mild to moderate depression with fewer side effects. Trials on patients with major depression, however, have come up empty handed.

From just a few examples we can see that certain natural compounds need no processing (quercetin and St. John’s Wort) while the natural compounds contained in others must be extracted or altered to avoid either toxic reactions or unpleasant side-effects (paclitaxen and aspirin). Other drugs, like ibuprofen and acetaminophen, are not based on naturally occurring compounds and are the products of pure ingenuity.

It is clear that effective medicine is not found solely in nature or the lab. In fact, many successful drugs are the product of teamwork between the diversity of nature and the ingenuity of people. In some cases, like St. John’s Wort for depression, the natural product can be just as effective as its pharmaceutical rival but in other cases, pharmaceuticals may be more effective. When faced with this problem, I defer to an old platitude: go with what works. In my case, it’s whatever will get me back on the hiking trails fastest.

Seen in the September 10, 2008 issue of the Brome County News

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