Cotton, for thousands of years one of the most important crops for clothing and shelter, might also become a source of food.

A chemical called gossypol makes cottonseed inedible for humans, though some of it is used in feed for cattle, which are less affected by the toxin.

Researchers at Texas A&M University have now genetically modified cotton to produce seeds with little or no gossypol.

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It's a step they say could help provide valuable protein to millions of people. Their findings are reported in Tuesday's issue of Proceedings of the National Academy of Sciences.

Keerti Rathore of the university's Institute for Plant Genomics and Biotechnology said the modified plants continue to have gossypol in their stems and leaves where it helps resist insects, but the chemical is significantly reduced in the seed.

Worldwide, 44 million tons of cottonseed is produced annually. It is grown in 80 countries and the seeds are 23 percent protein, Rathore said.

They are pressed for oil, and in the United States about half of the remaining meal goes into animal feed, he explained.

But, with the gossypol removed, the meal can be ground into flour and used in cooking, he said.

Rathore said he hasn't tasted the cottonseed meal, but added that researchers who had bred a different gossypol-free cottonseed had, and reported that tasted good.

Unfortunately, he said, that earlier version removed gossypol from all parts of the plant, which was then attacked by a variety of insects.

Jodi Scheffler, a research geneticist at the Agriculture Department's Agricultural Research Service center in Stoneville, Miss., said the development has potential.

"It definitely gives us new hope," said Scheffler, who was not part of Rathore's research team.

"This is an age-old problem," she explained, the protein contained in cottonseed is good, but cannot be used by people or most animals because it contains this toxin.

The potential problems that have to be worked out, she said, are determining whether the genetic change is stable through generations, and overcoming regulatory and public acceptance problems that can face any genetically modified foods.

One of the reasons it is important is for regions such as West Africa, where many small farmers grow cotton as a cash crop and would like to be able to use the seed to feed themselves and their livestock, she added.

Rathore's research was funded by the Texas Cotton Biotechnology Initiative, Cotton Inc., and the Texas Agricultural Experiment Station.