When my mom feels a UTI coming on, she buys some fresh cranberries and makes a smoothie as tart as she can handle. (Other ingredients she includes are yogurt, milk, honey, and apples.) It seems to fight it off quite well, she says. This way, it’s much more natural than the cranberry juice you can buy that’s pre-sweetened. It’s also much more concentrated; the stuff in stores is often diluted with cheaper juices, such as apple or pear juice.