Barbra Streisand apparently prefers food from her native blue-collar Brooklyn to posh-people fare like Champagne and caviar. And now RadarOnline.com can reveal she is paying a terrible price for her diet – and so is her husband James Brolin. An insider said the Memory singer loves “gigantic spreads of pastrami on rye, the sauerkraut, pickles, potato salad and coleslaw and banana cream pie even though it gives her heartburn and gas”. But despite her diet’s “unpleasant” consequences, she refuses to give up her favorite foods. According to a source, her food choices leave her “belching and fizzin…