This article reminds me that in preantibiotic days, tuberculosis patients were put on a fresh-air-and-sunshine regimen. Could the vitamin D so acquired account for the cures this system sometimes produced?

Nancy Axford
Sacramento, Calif.

Researcher John J. Cannell points to TB sanitariums as anecdotal evidence that sunlight fights infections. —J. Raloff Does the vitamin D in milk help protect against infection?

Graeme McRae
Palmdale, Calif.

Probably not, according to Michael Holick of Boston University, who has measured the vitamin’s content in milk. Far better, he says, would be cod-liver oil, with “a whopping 1,360 [international units of vitamin D] per tablespoon.” —J. Raloff

From the Nature Index

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