"Most plants employ chemical warfare to survive," says Bruce Ames, a senior scientist for nutrition and metabolism at Children's Hospital in Oakland, Calif., and professor emeritus at the University of California, Berkeley. He's also a member of the prestigious National Academy of Sciences, and inventor of the widely used Ames test, which helps screen for cancer-causing agents.
"Think about it," he told me. "Most plants the world over are poisonous and unfit for human consumption. That's how nature allows them to protect themselves from predators."
Yes, over millennia man has found a way to domesticate some of them, so to speak. But in the main, not many are edible. Those that are edible are still loaded with naturally occurring pesticides.
"In fact," he said, "99.99 percent of the pesticides you get from foods are naturally occurring toxins. And they are every bit as 'dangerous' as the synthetic variety."
Which, if you are consuming them as part of a normal diet -- and not at the astronomically high levels that cause some cancers in animal studies -- is, well, "not very." Or better put, it would be far more dangerous to eschew a diet full of fruits and vegetables and all the crucial cancer-fighting and other nutrients they provide than to consume the trace amounts of pesticides, whether naturally occurring or synthetically made, that come with all produce.
Essentially, Ames told me, forget the organic-vs.-conventionally-grown debate. What's important is that you eat your fruits and veggies -- and a lot of them.
I talked to Ames because a study just out in the Annals of Internal Medicine demonstrates -- again -- that organic produce has no more vitamins or other nutrients than does the often far less expensive conventionally grown variety.
But typically the debate over whether to shell out all that extra money for organic produce is less about the nutritional value than about the pesticide residue that may be clinging to the grapes or apples or lettuce. And, in fact, this analysis found that conventionally grown produce, as one would expect, is much more likely to have trace amounts of detectable synthetic-pesticide residue than its organic counterpart. It's worth noting, though, that here such residue could not be detected on most produce examined. And the trace amounts that were found were well within what is considered safe for human consumption.
Anyway, as I've written before, it's the widespread use of synthetic chemical pesticides and fertilizers that allows us to have cheap and widely available healthy foods in the first place. Strawberries in January in Chicago? As a child, my grandmother would have been amazed. A fertilizer that makes that peach grow bigger and with deeper colors so my kids actually eat it? That's money in the bank. Or, rather, nutrients in their systems.
Oh, and by the way, protection from E. coli, which can be present in natural fertilizers? Priceless.
Most interesting, though, Ames shared with me that he and his colleagues at Berkeley set up an extensive database of hundreds of animal-cancer studies done over decades. Researchers in these studies basically figure out what level of the chemical being studied would kill the animal immediately, they give it just a little less for its whole life and then ask, "Does it cause cancer?" Half the time when it comes to synthetic pesticides, the answer is "yes." But half the time when it comes to naturally occurring pesticides, the answer is "yes," too. And the latter is far more prevalent in our produce than anything man makes.
The point is not to be scared. Literally any substance is toxic in a high-enough dose. The point is to understand that eating something "natural" does not automatically confer amazing health benefits. What does? The same thing Mother always said: Eating lots of fruits and vegetables. And now we can add, from whatever the source.
Yep, nutrition fads come and go. But this is age-old wisdom that really can help us to age well.
(Betsy Hart is a columnist with Scripps Howard News Service and may be reached at firstname.lastname@example.org.)