Sweet Corn

The dirt: Genetically modified (GM) ingredients have always been hidden in foods, used to make additives like corn syrup or soy protein—until this summer. Biotech company Monsanto was successful in developing the first GM vegetable sold directly to consumers, and in getting it approved. The veggie in question? Sweet corn, one of summer's most coveted vegetables. Genetically engineered to produce its own pesticide (Bt, a bacterium that kills insects), the insecticide-laden GM sweet corn is not being sold at Whole Foods and Trader Joe's, both of whom refused to sell it. But Wal-Mart saw no problem with it and is selling it this summer, unlabeled, so you have no idea if you're serving up a side dish of Fraken-corn at your next barbecue.

Fix it: Load up on sweet corn from Whole Foods, Trader Joe's, or, better still, your local farmer's market, and whenever possible, look for certified-organic corn, which, by law, can't be genetically modified.