Monday, November 20, 2006

Grandma's Veggies

As if we didn't all ready have enough reasons to eat organic -from fish genes in tomatoes to enormous amounts of pesticides -here is yet another reason: today's conventional veggies are less nutritous than they were 50 years ago. This story is from NPR's weekend edition. The link to the transcript and the audio feed is below. On the radio they went on discuss how the differences disappeared in much organically grown produce.

Grandma's Veggies May Have Been More Nutritious
If you're looking for evidence that today's mass-produced vegetables don't quite measure up to those your grandparents ate, you can find it in data published by the US Department of Agriculture.
For more than a century, the USDA has measured levels of vitamins and minerals in American food. Donald Davis, a researcher at the University of Texas, compared the USDA figures from 1950 and 1999, for 43 common fruits and vegetables.
"Of the 13 nutrients that we were able to study, we found statistically reliable declines in six of the 13," he says. Levels of other nutrients stayed roughly constant over the years.
But a big word of caution: USDA nutritionist Joanne Holden says those 1950 numbers may not be trustworthy. For one thing, measurement techniques have changed, possibly changing the results. In addition, she says, no one knows whether the vegetables measured in 1950 were an accurate sample of the American diet.
It took until 1997 for the USDA to apply what could be called modern polling techniques to the analysis of food. At that point, the agency began gathering random samples of produce from supermarkets across the nation. USDA nutritionist David Haytowitz says USDA vegetable buyers follow strict rules to ensure the sample is truly random.
"We don't want them picking one off the top, because in the stores, they'll put the best ones on top," says Haytowitz. "We want an average one, a representative one."
This is important, because individual vegetables can vary enormously. The USDA found that some cantaloupes have four times more vitamin A than other cantaloupes.
University of Illinois plant geneticist John Juvik discovered that some stalks of broccoli had 40 or 50 times more glucosinolates -- compounds that can help prevent cancer -- than others.
"So you could go into the store one week, and buy a head of broccoli that would provide a dose of glucosinolates that would protect you from cancer," says Juvik, "but you could go back a week later and get one -- you couldn't see the difference -- and it would provide you very limited health benefits."
Vegetables can vary widely because of their genetic makeup and their environment. Juvik says plant breeders, until recently, didn't pay much attention to nutritional quality when they created varieties of vegetables.
"They were selecting for yield, marketable yield, and they were selecting for appearance," he says.
While many farmers and food companies may not know the best way to grow nutritious crops, it doesn't mean you should stop eating your fruits and vegetables.
Davis reminds people that the decline in nutrients in American produce is nothing compared to what people do to themselves.
"If you're really concerned about loss of nutrients in your diet," he says, "you probably ought to be looking first at how much of your calories are coming from added sugars, fats, and white flour and white rice."


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