Asparagus Fights Common Pesticide

Enzyme May Give the Veggie Pesticide-Fighting Powers

From the WebMD Archives

Sept. 23, 2004 -- Looking to limit your exposure to pesticides? You may want to develop a taste for asparagus. The skinny green stalks appear to contain an enzyme that degrades a commonly used pesticide called malathion.

Malathion is an organophosphate (OP) insecticide that has been registered for use in the U.S. since 1956. It is used in agriculture, residential gardens, public recreation areas, and in public health pest control programs. Because very small amounts of active ingredients are released per acre of ground, the exposure is believed to be well below the amount that might pose a health concern according to the EPA.

However at high doses, malathion can cause over stimulation of the nervous system causing seizures, nausea, and confusion. There is no conclusive proof that malathion causes cancer in humans, although some studies have shown an increased rate of cancer in people who are regularly exposed to pesticides, such as farmers and pesticide applicators.

Researchers Yasuko Okamoto and Takayuki Shibamoto from the University of California, Davis, department of environmental toxicology conducted lab tests on a variety of vegetables to find out if these produces can help eliminate some of those risks.

Specifically, the scientists wanted to see how well the veggies degraded malathion.

First, they went to local market to buy asparagus, carrots, kale, spinach, onions, broccoli, and garlic.

Back at the lab, Okamoto and Shibamoto washed the produce thoroughly, cut it up, and concocted an extract from each vegetable.

The next step in the researchers' "recipe" was mixing malathion with the extracts and letting it sit for four hours.

After four hours, the asparagus extract had all but eliminated the malathion, reducing it to a "nondetectable level," say the researchers.

The next best results under the same conditions came from the carrot, kale, spinach, and broccoli extracts.

Asparagus probably gets its malathion-fighting power from an enzyme contained in the vegetable, say the researchers.

Their study appears in the Sept. 22 issue of the Journal of Agricultural and Food Chemistry.

Pesticide Protection

Want to reduce your pesticide exposure without brewing your own asparagus extract? The U.S. Environmental Protection Agency offers these tips:

  • Wash and scrub all fresh fruits and vegetables thoroughly under running water. It will help remove bacteria and traces of chemicals from the surface, as well as dirt hidden in crevices.
  • Don't just soak produce. Use running water, which has an abrasive effect not provided by soaking.
  • Peel fruits and vegetables when possible to reduce dirt, bacteria, and pesticides.
  • Discard the outer leaves of leafy vegetables.
  • Trim fat from meat and skin from poultry and fish. Some pesticides' residues collect in fat.
  • Eat a variety of foods from several sources. You'll get a better mix of nutrients and lower your likelihood of exposure to a single pesticide.

The U.S. Department of Agriculture, which oversees organic labeling, provides information on organic food standards at its national organic program web site.

Show Sources

SOURCES: Okamoto, Y. and Shibamoto, T., Journal of Agricultural and Food Chemistry, September 22, 2004; vol 42: pp 5919-5923. News release, American Chemical Society. Environmental Protection Agency web site, "Pesticides and Food: Healthy, Sensible Food Practices." Department of Agriculture: "The National Organic Program."
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