The Dangerous and Seductive World of Phytochemicals
Among my many plant obsessions, growing and cooking with herbs and spices is one my favorite horticultural pastimes. Herbs are, after all, a bridge between two things I love: the garden and the kitchen. During this past winter, while confined to reading about gardening, my plant studies turned to ethnobotany, the study of the complex relationship of people and plants. What I read changed the way I look at those seemingly benign green lumps outside my kitchen.
First, I was struck by the awe and reverence that our ancestors had for these plants. From the earliest times, herbs and spices have been among the most highly prized and costly of ingredients. Entire empires rose and fell trying to control the trade of herbs and spices. Even before that, the religions of the ancient world viewed these plants as a means of spiritual fulfillment reached through sensuous experience (see Song of Solomon 4:12-15). Which prompts the question: was this infatuation and reverance just ancient superstition, or are these plants somehow powerful in mysterious ways? In the last ten years, new studies of plant's phytochemicals offer some answers.
“Plants are virtuosos of biochemical invention,” writes food science writer Harold McGee. The chemicals in plants are potent stuff. That boring potted oregano on your patio is actually an arsenal of phytochemicals. To chew on a raw leaf of oregano is not pleasant, and that’s mostly due to the toxicity of the chemicals in the plant. In fact, the purified essence of oregano and thyme can be bought from chemical supply companies with warning labels on them. Surprisingly, that’s exactly the plant’s goal. While animals can use their mobility to avoid predators, stationary plants resort to chemical warfare. Each plant produces thousands of strong, sometimes poisonous chemicals to ward off animals, humans, bacteria, and insects.
Herbs and spices stockpile aroma chemicals in oil-storage cells connected to glands on the surface of the leaves. Though we think of herbs or spices having a single flavor, they often contain a mixture of several aromatic compounds combined. So when you smell coriander seed, for example, you smell both flowery and lemony; bay leaves mix eucalyptus, pine, and flowery aromas. The individual flavor chemicals are a fascinating study unto themselves: cineole is found in sage, basil, and nutmeg and gives these plants their characteristic freshness; the phytochemical estragole gives tarragon its anise flavor; and safrole gives both the herb hoja santa and the root of the sassafras tree (from which root beer is derived) its distinctive “candy-shop” aroma.
The great irony is that humans have come to love these very plants that mean to do us harm. We have even learned to enjoy chemicals that are designed to hurt us. Think of the pungent sulfuric compounds of onions and the allium family, or the burn of capsicums from peppers. Ginger, mustard, horseradish, wasabi--we convert these weapons into pleasure through breeding and cooking. Cooking dilutes the effect of the essential oils. We still ingest these toxins, but at lower levels because they are mixed with other foods.
Science seems to confirm what our ancestors knew for centuries: that herbs and spices are seductive, yet powerful alchemists. I will never look at my potted oregano the same way again.
I have always wondered how humans have developed tolerances for plants that are so dangerous to other animals. And why they are so darn tasty!!ReplyDelete
Thymol is used as a miticide by Beekeepers.ReplyDelete
The toxic properties of herbs are why they have always been used as flavor enhancers and not as food crops themselves.ReplyDelete
It's amazing how we have developed a tolerance to these toxins. What a great point by sylvana and an informative (although scary) post.ReplyDelete
Funny, I have been studying the medicinal properties of herbs for quite a while. I love herbs. They are easy to grow, fun to cook with, and great to heal some simple ailments. But like all things, you do need to be well educated and proceed with caution. Rebecca LaatschReplyDelete
Great post! Thanks!ReplyDelete
This is a really good post. Enjoyed it!ReplyDelete
Who knew? Chemicals or not, I can't wait till I can go out with my scissors at dinner time and harvest me some fresh herbs...won't be long now. Thanks for the informative post.ReplyDelete
Nice post! I have a real thing for herbs too. I can't tell you how relieved I was that my garden is not in your "No They Didn't." Hope it stays that way!ReplyDelete
A huge herb lover here :)ReplyDelete
Here's an interesting link in the New York Times that talks about our genetic relationship to plants: http://www.nytimes.com/2010/04/27/science/27gene.html?hpReplyDelete
I love herbs almost as much for the fragrances as the tastes - but I do love them. I use them as filler with cut flowers as well. I'm not at all surprised that they can be toxic in certain quantities.ReplyDelete
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