Subway, the world's biggest food chain by the number of outlets, has just announced plans to start adding vitamin D and calcium to the bread it uses in its sandwiches, according to Nation's Restaurant News. One sandwich-worth of bread will now contain 30% one's daily value of vitamin D and 20% one's daily value of calcium, roughly the same as a glass of milk. The change affects all Subways' breads except English muffins and flatbreads.
More vitamins, overall, are probably a good thing. They certainly aren't a bad thing. And Subway has a track record of being relatively healthy, for a fast food chain. (Which is, of course, sort of like saying that The Idiot is relatively short, for a Dostoevsky novel.) But before we herald Subway as a beacon of healthfulness, we should take a moment to remember Michael Pollan's injunction against foods with health claims, and his warnings about the inefficiency of fortifying food. In Defense Of Food makes the persuasive argument that many nutrients are only beneficial to health when they work as part of a naturally occuring food complex. Vitamin D and calcium may not be as good for people without the other chemicals they accompany in milk.
Moreover, it's not even clear that Vitamin D is in short supply. Center for Disease Control data indicate that eight percent of Americans are vitamin-D-deficient, with 80-90% of Americans' vitamin D intake coming from sun exposure. So next time you're worried about not having enough D in your bloodstream, consider taking a long walk in the sun rather than ordering a $5 footlong.