December 11, 2003
by Dennis T. Avery
What if organic fruit and vegetable growers could prove that their produce is 10 to 15 percent more effective in combating cancer than conventional fruits and vegetables? Customers would flock to their doors offering to pay triple (up from the usual double) prices for such healthful foods.
Unfortunately for organic farmers, they can’t demonstrate any such healthy advantages in their produce. In fact, they’ve been unable to document any consistent, significant health difference in organic produce.
Instead, it’s researchers at the U.S. Department of Agriculture’s Beltsville research center who have been able to increase the healthfulness of already-healthful strawberries—by growing them at higher concentrations of CO2.
That’s right. More carbon dioxide in the air improves strawberries’ ability to cleanse our cells of the potentially carcinogenic free radicals produced by living and breathing.
Researchers already knew that strawberries are good sources of natural antioxidants. “Strawberries have shown a remarkably high scavenging activity toward chemically generated radicals,” they note. They theorized that adding more CO2 might improve the strawberries’ health-protecting powers because giving fruits more CO2 is like giving a human athlete more oxygen: it enhances performance.
Shiow Wang, James Bunce, and John Maas, all with the USDA’s Beltsville Agricultural Research Center, grew and harvested strawberries for two years in open-top clear-acrylic chambers. Two of the chambers had no added CO2, two had an added 300 parts per million CO2 above ambient air levels, and two had 600 ppm more CO2 than is currently in the air.
They found that the concentrations of nine different healthful flavinoids doubled in the 600 ppm CO2 chambers!
The researchers also found that the high-CO2 strawberries had higher concentrations of beneficial ascorbic acid and glutathione. Ascorbic acid levels increased by 10 percent in the 300 ppm added-CO2 chambers and 13 percent at in the 600 ppm added-CO2 chambers. Glutathione concentrations increased by 3 and 171 percent respectively.
Increasing CO2 levels for the plants also substantially increased their absorbance activity against such potentially harmful free radicals as peroxyl, hydrogen peroxide, superoxide and singlet oxygen.
Summing up, the USDA researchers said, “Strawberry fruit contain flavonoids with potent antioxidant properties, and under CO2 enrichment conditions, increased their ascorbic acid, glutathione, phenolic acid, flavonol, and anthocyanin concentrations.” They further noted further that “plants grown under CO2 enrichment conditions also had higher oxygen radical absorbance activity.”
I note this good-news strawberry experiment not because I think strawberry growers will soon start marketing CO2 enriched strawberries. (Actually, at triple prices, they might.)
The point I really want to make is that CO2 is not a pollutant, as too many global warming activists have made it seem. Instead, CO2 is the lifeblood of plant life all over the planet.
Nor is human-released CO2 associated with higher temperatures on the earth. Humans put only about 6 to 7 billion tons of CO2 into the atmosphere each year, while natural CO2 emissions from the land, oceans and volcanoes total more than 200 billion tons per year. The atmosphere itself contains some 750 billion tons of carbon dioxide, in dynamic equilibrium with about 37 trillion tons of inorganic carbon dissolved in the oceans.
If every molecule of CO2 ever emitted from every factory, car, power mower, and barbecue in human history were still in the atmosphere, it still wouldn’t account for the change in the earth’s CO2 since 1950.
Moreover, recent studies of the Antarctic by the Scripps Institute of Oceanography show that after the last three Ice Ages, CO2 concentrations increased naturally—200 to 800 years after the warm-up began! If there’s a linkage, higher atmospheric CO2 is the result of increased warming, not the cause. That’s the opposite of what the global warming advocates have told us.The earth is apparently in the midst of another mild, natural warming cycle. (By the testimony of the iceberg debris in the North Atlantic, we’ve had nine of these in the last 12,000 years.) In the midst of the doom and gloom over rising world temperatures (moderate and beneficial as the rise has been over the last 150 years) it’s good to know that the strawberries will probably become even more healthful several hundred years from now.
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
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