Don’t mess with Mexico’s maíz: Constitutional amendment to ban GMO corn seeds

MEXICO CITY — There’s a popular saying in Mexico, where corn is as central to national mythology as it is gastronomy.

Sin maíz, no hay país. Without corn, there is no country.

This week, Mexico’s leaders voted to enshrine that concept in the Constitution, declaring native corn “an element of national identity” and banning the planting of genetically modified seeds.

The measure, which aims to protect Mexico’s thousands of varieties of heirloom corn from engineered versions sold by American companies, has become a nationalist rallying cry. Support for the reform has only grown in recent months as Mexico has fended off insults, threats of tariffs and even the specter of U.S. military intervention from President Trump.

“Corn is Mexico,” President Claudia Sheinbaum said recently, describing the reform as a way to secure Mexico’s sovereignty. “We have to protect it for biodiversity but also culturally, because corn is what intrinsically links us to our origins, to the resistance of Indigenous peoples.”

Felipe Martinez harvests his corn on his farm in San Jeronimo Xayacatlan.

(Associated Press)

The amendment to the Constitution comes after the defeat in December of a related effort that sought to phase out all imports of genetically modified corn. Then-President Andrés Manuel López Obrador issued a presidential decree in 2023 banning the use of genetically engineered corn in dough and tortillas and for animal feed and industrial use, but a trade dispute panel ruled that it violated the U.S.-Mexico-Canada Agreement.

Mexico agreed to abide by the panel’s ruling, and this week’s action targets seeds, not all products.

The amendment received the last approval needed from Congress on Wednesday and it has been sent to Sheinbaum for her signature. It was also approved by a majority of state legislatures.

Every year the U.S. sells Mexico about $5 billion of genetically modified corn, which has been designed to resist pests and tolerate herbicides. Most of that corn is used to feed livestock.

Even before the constitutional reform, it was mostly illegal to plant modified corn in Mexico thanks to a 2013 lawsuit brought by farmer activists. But experts say it still happens. And they say the presence of engineered seeds and corn in Mexico threatens the vast diversity of maize crops here, which span from burnt orange to purple and pink and which have been adapted over centuries to be grown at different altitudes and climates.

“There’s a disturbing level of contamination of native maize with genetically modified traits,” said Timothy Wise, a researcher at the Global Development and Environment Institute at Tufts University. Some ancestral varieties of Mexican corn have already gone extinct, he said, “the product of illegal plantings and uncontrolled and undetected cross-pollination.”

That alarms many in Mexico, where corn has become not just a staple of the diet but a symbol of Mexico itself.

Corn was born here about 9,000 years ago, when Mesoamerican farmers started to domesticate the wild grass known as teosinte.

It has been revered here ever since, with sculptors carving images of Centeot, the Aztec deity of corn, into pre-Hispanic temples and artists such as Diego Rivera and Frida Kahlo prominently featuring corn husks, cornfields and corn dishes in their paintings.

The poet Octavio Paz was one of many to extol the plant’s virtues, saying, “The invention of corn by Mexicans is only comparable to man’s invention of fire.”

Probably no people in the world get a larger share of their calories from corn than Mexicans, with researchers estimating that the average person here eats one to two pounds per day.

A man sells corn in Coatzacoalcos, Veracruz.

(Gary Coronado / Los Angeles Times)

It is mashed into masa and cooked into tortillas, tamales and tlacoyos. Its kernels are soaked in fragrant pozole and brewed into a hearty breakfast drink known as atole.

“It’s at the root of our culture, giving us strength and identity,” said María Elena ?lvarez-Buylla, a researcher in molecular genetics at the National Autonomous University of Mexico. “It’s our staple. Losing sovereignty over a fundamental aspect of our life and health is very risky.”

?lvarez-Buylla led Mexico’s National Council on Humanities, Science and Technology until last year, and has published studies claiming risks to health and the environment from genetically modified corn and the herbicides associated with it.

She says U.S. corn is less nutritious than the Mexican version and is linked to liver disease and other problems. Her research found that 9 in 10 tortilla samples from several cities in Mexico had traces of genetically modified corn.

The U.S., its farmers and the companies that sell engineered corn seeds reject Mexico’s claim that their products come with risks.

They celebrated the December trade dispute ruling, which came after a concerted lobbying effort by corn producers in states such as Iowa, Illinois and Nebraska. “This win illustrates the power of corn advocacy,” said Kenneth Hartman Jr. of the National Corn Growers Assn.

Mexico was an exporter of corn until as recently as the 1980s. The passage of the North American Free Trade Agreement in 1994, which laid the groundwork for the current trade pact, changed that.

Many small family farms in Mexico could not compete with big U.S. farmers who enjoy hefty federal subsidies. In the three decades since NAFTA took effect, annual corn imports to Mexico grew from roughly 3.1 million metric tons to nearly 23.4 million metric tons, according to the U.S. Department of Agriculture and the U.S. Grains Council.

The change forced many Mexican farmers to shift to subsistence farming or to take up seasonal work far from their homes. Many others left to find work in the United States.

Wise said it was ironic that the U.S. had used the free trade agreement to oppose Mexico’s efforts to ban corn imports at the same time that Trump imposed — and then reversed — tariffs on U.S. imports.

U.S. trade policy, he said, appears to be: “We’ll ignore the agreement when it’s convenient for us. We’ll enforce it when it has an impact on some biotech companies.”

He said Mexicans had long ago decided that they don’t want genetically modified corn, and that it largely came down to one thing: taste.

“Nobody wants to eat it,” he said.

Special correspondent Cecilia Sánchez Vidal in Mexico City contributed to this report.