It's a tremendous way of getting people to buy more at lower cost to the producer. There's no question that that's an incentive to buy. Everybody loves a bargain.

FDA, which regulates the safety of vegetables, doesn't have those kinds of rules because Congress doesn't want it to. It's not that the vegetables themselves have anything wrong with them; it's that they're contaminated with animal manure. One of the rationales for a single food safety agency is that you can't separate animals from vegetables.

What we know about diets hasn't changed. It still makes sense to eat lots of fruits and vegetables, balance calories from other foods, and keep calories under control. That, however, does not make front-page news.

The real reason for health claims is well established: health claims sell food products.

One way in which we can encourage the Chinese government to take more vigorous action to control food safety in their country is by just saying we're not going to buy Chinese foods until they get their system cleaned up. Admittedly it's a difficult system to get under control because an astonishing percentage - maybe 80 percent - of the foods in China are produced in small backyard operations.

The problem with nutrient-by-nutrient nutrition science is that it takes the nutrient out the context of the food, the food out of the context of the diet, and the diet out of the context of the lifestyle.

You need to identify the steps at which contamination can occur - those are the critical control points. You take steps to make sure that that doesn't happen. And you monitor and evaluate and test to make sure that your system is working properly. And if it's done diligently and done faithfully and monitored carefully, then they're producing safe food. And no astronaut of which I'm aware has ever gotten food poisoning in outer space.