The compounds plants produce to protect themselves may also protect human health | The Old Farmer's Almanac

More Good Reasons to Eat Your Vegetables

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Think about plants. We can learn from the way they keep themselves healthy, and there are many ways that plants help human health.

“Plants are the master chemists,” says Mary Ann Lila, who directs the Plants for Human Health Institute at North Carolina State University. “Because plants can’t move around, they have to manufacture what they need, not merely to grow and reproduce, but to defend, protect, and heal themselves.”

To botanists, plants manufacture good stuff called “phytocompounds” (aka phytochemicals or phytonutrients, from the Greek word phyto for plant)—chemicals manufactured for purposes other than growth and survival.

Every plant produces a unique, self-protecting pharmacy to defend against pathogens, excess radiation, predators, and other stressors. Under stress, plants even produce their own anesthetics! 

Researchers have identified about 4,000 phytocompounds, and suspect there could be many thousands more, even in a single plant. Combinations of these chemicals give plants their unique colors, flavors, tastes, and smells.

Undestanding Plants in Human Health

In recent decades, agricultural researchers have begun to discover how plants manufacture (“biosynthesize”) their own chemicals. In turn, medical and veterinary researchers have begun exploring the ways animals, including humans, can (or do) take advantage of these health and life-protecting compounds.

The benefits are numerous:

  • Plant phytochemicals can mimic hormones, stimulate or inhibit enzymes, act as blood-thinners or free-radical scavengers, relax muscles and blood vessels, reduce inflammation in artery walls, help the body remove toxins, prevent bacteria from sticking to and infecting cells, prevent or slow the growth of cancerous cells.

So why not simply extract them from plants and put them into pills or potions? That day might come but not before a lot of research. “When you start taking [plants] apart, the compounds don’t act like they do in the whole food. In fact, extracts can even produce the opposite effect, especially in high doses,” said the late James Joseph, a neuroscientist and senior researcher at the Tufts University Human Nutrition Research Center on Aging in Boston.

“If you take something out of a plant and put into a pill, it’s more expensive, probably less effective, and possibly dangerous,” says retired USDA ethnobotanist James A. Duke, author of 30 books and an authority on medicinal plants. “Plus it’s not occurring with its natural synergists. Most phytocompounds work together, with synergistic or additive effects.”

All green plants manufacture a broad variety of anti-inflammatory, antibiotic, and antioxidant compounds. The ongoing research into how these compounds do or might affect human health is complicated. To date, much of it focuses only on laboratory experiments or trials with lab animals, none of which necessarily predicts what will happen in a human.

For now, experts recommend eating a wide variety of vegetables and fruits, both raw and cooked, to ensure an ample intake of health-promoting phyto-compounds.

Image: Periwinkle plants are the natural source of anticancer medicine. Credit: Patrick Gillooly, MIT

About The Author

Margaret Boyles

Margaret Boyles is a longtime contributor to The Old Farmer’s Almanac. She wrote for UNH Cooperative Extension, managed NH Outside, and contributes to various media covering environmental and human health issues. Read More from Margaret Boyles