One of the biggest trends in food marketing are so-called “functional foods.” These days it’s not enough that food imparts nutrition and makes you not hungry, it has to perform jumping jacks. Yogurt for your digestive system, milk for your brain, and crisped rice cereal for your immune system. Food packagers don’t outright say that they cure or prevent disease, they can get away with using words like “supports” and “promotes” to make their claims, as long as there’s a little bit of believable science to back it up. But are they really about health, or hype? NYT investigates.