By Marc Kaufman
Washington Post Staff Writer
Monday, November 3, 2008

For years, advocates of agricultural biotechnology have promised a future in which foods will be genetically engineered to give more nutrition and to prevent chronic diseases, in which crops will be modified to thrive in salty soil or hot or dry climates and in which consumers will benefit directly from science's ability to tweak other characteristics of plants.

So far, however, that has generally not happened, and the main beneficiaries of agricultural biotechnology remain farmers battling pests and weeds that threaten staple crops such as soybeans, corn and cotton, as well as the companies that develop and produce genetically modified seeds.

But last week, consumers were reminded of what might be available in the future. Researchers at the British-government-sponsored John Innes Center announced that they had developed a purple tomato that has high levels of beneficial anthocyanins -- antioxidants known to neutralize potentially harmful oxygen molecules, or free radicals, in the body and reduce the risk of heart disease and cancer. The genes for the purple tomato came from snapdragons.

The creators of the purple tomato, a team led by Cathie Martin, tested their fruit in cancer-susceptible mice and found that the animals on a diet of 10 percent powdered purple tomatoes in their pellets lived significantly longer than those eating powdered normal red tomatoes. Her findings were published in the journal Nature Biotechnology.

This advance does not mean that extra-healthful purple tomatoes will be on the market anytime soon -- that would require much more testing in animals and humans and, perhaps a bigger hurdle, finding a company that wants to develop, market and sell them.

But Martin said the tomatoes are important because they are a promising example of a genetically modified food "that offers a potential benefit for all consumers." That's because the anthocyanins -- which are also found in many berries and in red cabbage -- would be delivered at high levels in a product that is widely and frequently consumed.

"The goal here is to improve diets by putting important compounds like anthocyanins in foods everyone eats," Martin said.

Researchers are genetically modifying many other foods to be more nutritious or to carry extra health benefits -- including staples such as rice, cassava and bananas, as well as vegetable oils engineered to have higher levels of healthful omega-3 fatty acids. Some are working on engineering ingredients in beer and white wine to boost levels of the antioxidant resveratrol, a heart-healthy compound found especially in red wine.

Unlike the explosion in biotechnology to protect crops from insects and weeds, these modified consumer products are in the relatively early stages of development, and there is seldom much money supporting their research. What's more, they often require the introduction of two or more new genes into the existing plant or, as in the case of the purple tomato, the insertion of a "transcription factor" that controls the activity of numerous genes. The health risks of this broader-brush genetic engineering have been far less studied than those that involve modifying or inserting a single gene.

Nonetheless, advocates of food biotechnology say the promise is there. Michael Wach, managing director for science and regulatory affairs at the Biotechnology Industry Organization, said many researchers are experimenting with ways to engineer more healthful fats, more nutritionally dense products, and foods with increased levels of iron, zinc and Vitamin A.

It remains unclear whether any will pan out, but he said the traditional products of biotechnology that help farmers are becoming ever more important in poor nations as well as developed ones. About 282 million acres of genetically modified crops are planted in 23 nations.

"The issue of food availability is becoming increasingly important, and we know that genetically modified crops can help," he said. "With all the research now into developing crops that can resist drought or poor soil, we think the importance of biotechnology to agriculture can only grow."

Margaret Mellon, a food specialist with the Union of Concerned Scientists, disagrees. She generally views today's genetically modified crops as a problem rather than a solution. Although biotechnology could someday help increase the yields of staple crops and make them more resistant to climatic stress, she said, foods modified for nutritional benefits have fared poorly and can be produced better by conventional methods.

"The big biotech firms always used the promise of consumer-friendly, extra-healthy foods to fend off some of the criticism of their pesticide- and herbicide-control products, which often were not terribly popular with the public," she said. "It doesn't look exactly promising that we'll get any of that kind of benefit anytime soon, if ever. Clearly, genetically engineering fruits and vegetables for nutritional benefits has proven far more difficult than the industry expected."

And even if vegetables and fruits can be genetically modified to contain an abundance of a beneficial compound, she asked, do we really want them? Wouldn't it be better, she said, to develop richer soils -- using microorganisms and nutrients -- that could boost the nutritional value of all edible plants?

Martin, the creator of the purple tomato, said conventionally bred and grown fruits, vegetables and berries can certainly supply the nutrients and minerals that people need. But nutrition experts say that would require eating five servings a day, she said, and "eating one tomato instead certainly would be easier and more likely to happen."