Here We Go Again

Science is again reversing itself. This time: Sunshine may help prevent cancer, and perhaps we shouldn't be using all that sunscreen. Link. Opening paragraphs:

Scientists are excited about a vitamin again. But unlike fads that sizzled and fizzled, the evidence this time is strong and keeps growing. If it bears out, it will challenge one of medicine's most fundamental beliefs: that people need to coat themselves with sunscreen whenever they're in the sun. Doing that may actually contribute to far more cancer deaths than it prevents, some researchers think.

The vitamin is D, nicknamed the "sunshine vitamin" because the skin makes it from ultraviolet rays. Sunscreen blocks its production, but dermatologists and health agencies have long preached that such lotions are needed to prevent skin cancer. Now some scientists are questioning that advice. The reason is that vitamin D increasingly seems important for preventing and even treating many types of cancer.

In the last three months alone, four separate studies found it helped protect against lymphoma and cancers of the prostate, lung and, ironically, the skin. The strongest evidence is for colon cancer.

Has anyone seen a book that chronicles all of science's wrong assurances over the last, say, 100 years? It could start with eugenics and then proceed through the great sun scare. It'd probably make a great source of income for some enterprising young scientists: he could publish an update every six months.