A shopper surveys the produce at
Pacifica Farmers Market in Pacifica, Calif., in 2011.
AP
Yes, organics is a $29 billion industry and still growing. Something is pulling
us toward those organic veggies that are grown without synthetic pesticides or
fertilizers.
But if you're thinking that organic
produce will help you stay healthier, a new finding may come as a surprise. A new study published in the Annals of Internal Medicine
finds scant evidence of health benefits from organic foods.
"There's a definite lack of
evidence," says researcher Crystal Smith-Spangler at Stanford University
School of Medicine, especially when it comes to studies of people.
She and her colleagues collected 200
peer-reviewed studies that examined differences between organic and
conventional food, or the people who eat it.
A few of these studies followed
people who were eating either organic or conventional food and looked for
evidence that the choice made a difference in their health.
One study, for instance, looked at whether
eating organic food while pregnant would influence the likelihood of eczema and
other allergic conditions among children, and another looked at whether eating
organic meat would influence the risk of a Campylobacter infection, a
bacterial food-borne illness. When the researchers looked at the body of
evidence, they found no clear benefits. But they say more research is needed.
It's important to note, though, that
such studies have a really hard time uncovering subtle effects of our
environment, or what we eat, on our health. Too many other powerful influences
get in the way. Also, these studies only followed people for a very short time
— about two years or less. That's hardly enough time to document any particular
health benefit.
Most of the studies included in this
collection looked at the food itself — the nutrients that it contained as well
as levels of pesticide residues or harmful bacteria.
As you might expect, there was less
pesticide contamination on organic produce. But does that matter? The authors
of the new study say probably not. They found that the vast majority of
conventionally grown food did not exceed allowable limits of pesticide residue
set by federal regulations.
Some previous studies have looked at specific organic
foods and found that they contain higher levels of important nutrients, such as
vitamins and minerals. We've reported on one particularly ambitious experiment, which is supposed to go on
for a hundred years, comparing plots of organic and conventional tomatoes.
After 10 years, the researchers found that tomatoes raised in the organic plots
contained significantly higher levels of certain antioxidant compounds.
But this is one study of one
vegetable in one field. And when the Stanford researchers looked at their broad
array of studies, which included lots of different crops in different
situations, they found no such broad pattern.
Here's the basic reason: When it
comes to their nutritional quality, vegetables vary enormously, and that's true
whether they are organic or conventional. One carrot in the grocery store, for
instance, may have two or three times more beta carotene (which gives us
vitamin A) than its neighbor. That's due to all kinds of things: differences in
the genetic makeup of different varieties, the ripeness of the produce when it
was picked, even the weather.
So there really are vegetables that
are more nutritious than others, but the dividing line between them isn't
whether or not they are organic. "You can't use organic as your sole
criteria for judging nutritional quality," says Smith-Spangler.
Of course, people may have other
reasons for buying organic food. It's a different style of agriculture. Organic
farmers often control pests by growing a greater variety of crops. They
increase the fertility of their fields through nitrogen-fixing plants, or by
adding compost instead of applying synthetic fertilizer.
That can bring environmental
benefits, such as more diverse insect life in the field or less fertilizer
runoff into neighboring streams. But such methods also cost money. That's part
of what you are buying when you buy organic.
So if you really want to find the
most nutritious vegetables, and the organic label won't take you there, what
will?
At the moment, unfortunately, there
isn't a good guide. But a lot of scientists are working on it.
They're measuring nutrient levels in
all kinds of crops, and discovering some surprising things, as The Salt
reported last week — such as supernutritious microgreens. They're trying to breed new
varieties of crops that yield not a bigger harvest but a more nutrient-rich
harvest.
The problem is, farmers still get
paid by the pound, not by the vitamin. And consumers buy their food the same
way. What this really requires is a whole new food system that can track those
extra-nutritious crops from farmer's field to consumer's shopping basket.
Maybe, down the road, you will
actually see signs in the supermarket that advertise, for instance, iron-rich
beans. Maybe they'd be organic, or maybe not.
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