Farm Progress

Bt corn can reduce serious birth defects by limiting toxic mold

November 6, 2004

6 Min Read

In the early 1990s, Hispanic women in the Rio Grande Valley of Texas gave birth to babies with neural tube defects (NTDs) at a rate of 33 per 10,000 live births, approximately six times the U.S. national average for non-Hispanic women. Neural tube defects include spina bifida, hydrocephalus, and anencephaly.

Most unborn children affected by NTDs do not even survive to birth, and those who do are usually severely disabled. One hundred eighty-four Mexican-American women and their babies suffered these devastating conditions during the early 1990s.

The precise cause for the increased rate of NTDs in Texas remained a mystery until recent research shed light on a surprising cause. Studies from China, Guatemala, South Africa, and the United States show that a clear link exists between diets containing unprocessed corn (known as maize in most of the world) and NTDs. Unprocessed corn is found in tortillas and other products that contain whole ground corn. Research (Acevedo, 2004) in Guatemala showed that in four rural departments the children of women who ate unprocessed corn as a significant part of their diet had a rate of NTDs (34.29 per 10,0000 live births) at least six times the world rate.

What connection could exist between unprocessed corn in the diet and children being born with NTDs? Fumonisin, a deadly mycotoxin found in unprocessed corn is the likely culprit according to research published in the Journal of Nutrition (Marasas, April 2004). At the time that the Hispanic women of the Rio Grande valley suffered the high rate of NTDs in their babies, the fumonisin level in corn in the Rio Grande Valley was two to three times the normal level. These women also reported much higher dietary consumption of homemade tortillas prepared from unprocessed corn. Mycotoxins such as fumonisin are highly toxic chemicals that are produced by molds and fungi. When corn is attacked by insects a mold called Fusarium can grow at the site of insect damage and produce fumonisin. Poor storage conditions can promote post-harvest growth of molds on grain as well.

Blocks folic acid

The April 2004 research also made another important connection. Researchers learned that fumonisin interferes with the cellular uptake of folic acid. Folic acid in the diet, provided either directly from the foods eaten or through food fortification and dietary supplements, is known to reduce the incidence of NTDs in developing fetuses. Because fumonisin prevents the folic acid from being absorbed by cells, women eating a diet of unprocessed corn contaminated with fumonisin are at higher risk of giving birth to babies with NTDs even when their diet contains the adequate amount of folic acid.

It turns out that there is a way to limit toxic mold infestation in corn. Researchers in Argentina, France, Italy, Spain, Turkey, and the United States have clearly established that planting corn seeds genetically engineered to be resistant to corn borers and similar insect pests results in the harvesting of corn with much lower levels of fumonisin. The insect protected corn varieties contain a protein that is found in a common soil bacterium called Bacillus thuringiensis. In nature, this bacteria kills certain insect larvae but is harmless to all other insect species, as well as humans and animals. Bt preparations have been safely used for years in agriculture and are one of few insect control methods used in organic agriculture. Using this knowledge, scientists engineered corn that could produce the protein in the hopes of making insect-protected corn plants. This genetically improved corn, dubbed Bt corn, usually has drastically lower levels of fumonisin. It is not unusual for Bt corn to have one-tenth to one-twentieth the amount of fumonisin that is found on organic and conventional corn varieties.

The U.S. Food and Drug Administration and the UK Food Safety Agency have established guidance levels for recommended maximum fumonisin levels in food and feed products made from corn. Even before the connection of fumonisin with NTDs, food safety agencies recognized fumonisin as a highly toxic carcinogen. Although highly processed cornstarch and corn oil are unlikely to be contaminated with fumonisin, unprocessed corn or lightly processed corn (e.g., cornmeal) can have fumonisin levels that exceed recommended levels.

Cornmeal tests

The UK Food Safety Agency tested six organic cornmeal products and 20 conventional cornmeal products for fumonisin contamination in September 2003. The six organic cornmeals had fumonisin levels nine to 40 times the recommended levels for human health. All six organic cornmeal products were voluntarily withdrawn from grocery stores.

Genetically improved Bt corn kernels are less often damaged by insects, greatly reducing the chance of fumonisin contamination and its harmful effect. This health benefit adds to the benefits that Bt corn has already brought to farmers and consumers. Farmers have found that Bt corn improves yields and lowers their labor costs. Bt corn also reduces pesticide use. Improved yields and reduced costs mean grain prices are kept low.

Require Bt corn?

Perhaps faced with results like these, government regulators around the world should require farmers to plant Bt corn. Unfortunately, farmers are often discouraged from planting Bt corn. It is no secret that opponents of agricultural biotechnology have slandered transgenic crops. These crops have passed rigorous safety reviews by government regulatory agencies in many nations, including the U.S. Environmental Protection Agency, the Food and Drug Administration, and the Department of Agriculture experts say transgenic crops are safe but opponents ignore the scientific facts and place scare stories in the media here and abroad.

Understandably, some consumers respond to these scary, inaccurate claims by avoiding foods containing transgenic crops like Bt corn. Some politicians respond by placing inappropriate barriers to the adoption of these crops. The problem with these fright reactions is that by diverting attention from the real risks in our food supply (such as fumonisin in corn), our society suffers real damage and losses that could and should be avoided. Women of child-bearing years may be hoping to eat a healthier diet by selecting organic corn when in fact, the transgenic Bt corn would be a healthier and less expensive choice, assuming they are allowed the choice. Women of child-bearing years should not be forced by opponents of Bt corn into a higher risk of bearing a child with an NTD. As Izelle Theunissen of the Medical Research Council of South Africa has written, “So despite the current discussions surrounding GM foods, it appears that Bt maize hybrids could play a major role in lowering fumonisin levels in maize products, which should ultimately enhance the quality and safety of maize for animal and human consumption, particularly in the African context.”

While opponents of transgenic crops force our attention and our research dollars to over-regulate transgenic crops, are we ignoring the major risks associated with food? We know that major risks associated with food in the United States are obesity, poor nutritional quality of our diets, the possible presence of organisms that could cause illness, and the unrecognized presence of natural toxins such as fumonisin.

While many are convinced that organic food is healthier, it is no more nutritious than conventional food. As shown by the recall of fumonisin-contaminated organic corn meals, organic food, at times, may be less safe. Organic food is not the answer to known food risks.

Perhaps one recourse for harm done by irresponsible opposition to transgenic crops will be a lawsuit against producers and manufacturers of fumonisin-laden corn products. Will our courtrooms be the place that distinguishes the Bt corn science fiction from fact?

(Bruce Chassy is professor of Food Microbiology and Nutritional Sciences and executive associate director of the Biotechnology Center, University of Illinois Urbana-Champaign; Drew Kershen is Earl Sneed Centennial professor of law, University of Oklahoma College of Law, Norman, Okla.)

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