John thanks for the response
I agree this is a huge subject, I agree that too often (overworked/lazy/impatient/out of date - take your pick based on your prejudice) GPs over-prescribe medicines, there are also cases of pharmaceutical cos "bribing" GPs to prescribe their particular treatment as opposed to someone elses.
Many substances have side effects depending on dosage, including naturally occurring substances, also most vitamin tablets available in the high street are "manufactured" rather than naturally produced, so as to ensure consistent quality , purity, stength etc.
Of course there is dubious science on both sides of the divide I would heartily recommend the following sites for exposing the fakes, quacks, imposters, charlatans and snake oil salesmen trying to win us over with their magic potions
Bad Science
http://www.badscience.net/
Quackwatch - Your Guide to Quackery, Health Fraud, and Intelligent Decisions
http://www.quackwatch.org/
PharmaGossip - Looking beyond the PR spin of big pharma
http://pharmagossip.blogspot.com/
Bad Homeopathy -
http://www.jonn.co.uk/badhomeopathy/modules/news/
HealthWatch - the independent charity not the gov one
http://www.healthwatch-uk.org/