He’s ready for a tsunami of criticism with his latest foray into debunking popular wisdom – “Do You Believe in Magic?: The Sense and Nonsense of Alternative Medicine” in which he takes on the vitamin and herbal supplements industry, alternative medicine of all kinds, Congress and celebrity doctors who peddle their own products. It hits the shelves on Tuesday.

“Yes, I do get hate mail,” Offit admits. He makes the case that the vitamin industry in particular has successfully lobbied to keep itself unregulated while selling billions of pills to an eager and gullible public. “People think of dietary supplements as natural, benign and helpful,” Offit told NBC News. “People don’t think of them as drugs.”

Yet studies have shown that not only do vitamin supplements fail to lower cancer risk, but they can actually cause cancer – most notably the 1994 Finnish study that found smokers who took beta carotene – which the body converts to vitamin A – actually had a higher risk of lung cancer than men who didn’t take the supplements. Alternative therapies of all kinds are often not only of no benefit whatsoever -- they can be harmful, he notes.