Admittedly, those ideas are merely in their "test-plot" stage. But less fantastical genetically modified flora is becoming our food reality.

"I could have made the film a lot more disturbing than it is," says Future of Food director Deborah Koons Garcia, who will be screening the film at the Brattle on October 21. "But my whole point was to inspire people to take action."

Garcia wants people to take action at grocery stores, farmers’ markets, and local farms, where consumers have the power to choose what goes into their mouths. On the phone from her house in California’s Bay Area — where she lives and works in the house that she and husband Jerry Garcia of the Grateful Dead bought before his death in 1995 — Garcia says that genetically engineered foods are changing our farming and agricultural landscape.

A vegetarian since she went to college in North Carolina and read Frances Moore Lappe’s Diet for a Small Planet, Garcia set out to make a film about food and pesticide use. But she soon discovered the disturbing world of genetic modification, where, for instance, scientists use things like "gene guns" to insert pesticide-resistant genes into tomatoes. That way, huge fields can be sprayed with pesticides without killing the crop. The process has allowed the huge agbiotech corporation Monsanto to corner both the seed and pesticide markets while shutting out small growers and throwing international farming systems out of whack.

Garcia paints a future that could include genetically engineered livestock and fish, and vegetables sprayed with pesticides as toxic as Agent Orange, leading to what one of the movie’s subjects calls "the largest biological experiment man has ever entered into."

Fresh, organic, and healthy foods form the foundation of what Garcia calls a "counter-revolution ... where people are very conscious of their food choices."

For now, the lack of required labeling on genetically modified fare makes it hard to know what you’re eating. "People are being disconnected from their food in general," Garcia says. "You’re not feeding yourself, you’re just fueling. It becomes more compulsive, it becomes more unhealthy."

The Future of Food opens on October 21 at the Brattle Theater | 40 Brattle Street, Cambridge | 617.876.6838 | www.brattlefilm.org | Deborah Koons Garcia will sit on a panel with other food-policy experts following the 7:30 pm showing on October 23.