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GMO: Label Genetically Modified Foods?

Californians will vote this November on whether or not genetically modified foods should be labeled. I've heard persuasive arguments pro and con and can't decide between them. What’s your take on this issue? 

Answer (Published 10/23/2012)

Foods that contain genetically modified organisms (GMO) have been with us since 1996, but most people are unaware that about 90 percent of the corn, soybeans, rapeseed (the source of canola oil) and sugar beets grown in the United States are GMO. These crops contain bacterial DNA that makes soybeans resistant to a weed killing herbicide and enables corn to produce its own insecticide. Those soybeans and corn end up in cereals, snack foods, salad dressings and other foods we regularly consume.

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The ongoing battle over labeling is currently focused on the California referendum in which voters will get to decide the issue. In the past, the arguments have been debated only in state legislatures, where those in favor of informing the public about what their foods contain have been defeated.

The arguments for and against labeling are pretty obvious:

  • Those in favor of labeling (myself included) believe that consumers have a right to know when foods are modified with genes from another species. On this side of the issue are environmental and consumer groups and the organic farming industry.
  • Those against labeling include many conventional farmers, manufacturers of industrial food such as Kellogg’s and Kraft, as well as Monsanto and other big agricultural biotechnology companies. Scientists who have taken this position maintain that genetically modified crops reduce the need for herbicides and pesticides, thus benefitting the environment as well as reducing loss to insect predation. Better water quality is an environmental benefit of the elimination of herbicides and pesticides that has already been realized in some areas. 

The advantages to farmers - lower production costs, fewer pest problems, reduced use of pesticides, and better yields compared to conventional crops - were spelled out in a 2010 report on GMO crops from the National Academy of Sciences. The report noted, however, that widespread cultivation of genetically modified crops resistant to the herbicide glyphosate used in many commercial weed killers could stimulate weeds to develop their own resistance to glyphosate. Another issue discussed in the report: GM crops produce a bacterial toxin (BT, from Bacillus thuringiensis) that is deadly when consumed by susceptible insect pests. Two insect species have already developed resistance to it. Organic gardeners are likely to lose this useful tool as pests become resistant; moreover, humans have never consumed BT in significant amounts, and long-term health effects are unknown.

According to the Grocery Manufacturers Association, processed foods including breakfast cereal, granola bars, chicken nuggets and salad dressing now contain one or more ingredients from crops that have been genetically modified. Corn, sugar, soy protein, cornstarch and vegetable oil almost always come from genetically modified crops.

To date, no identified food safety issues have emerged as a result of the consumption of foods that include products including these GM crops, but some experts say it’s too soon to observe any negative impact on human health.

Another issue: last year (2011) the Department of Agriculture deregulated a new alfalfa created by Monsanto over the protests of the organic farming industry. The concern is that alfalfa pollen drifts easily from one field to another and the GMO pollen could easily contaminate organic crops used to feed dairy cows that are the source of organic milk.

This issue is a complex one with many questions unanswered. For that reason, and certainly until the answers are clearer, labeling GMO foods makes sense to me.

Andrew Weil, M.D.

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