Prevention

[The Tree]

How are scientists/doctors able to say that such a thing prevents such an illness.surely if it doesnt happen how do they know if it is natures course or the preventive substance

[jno]

that's what medical trials are for. They can, for instance, give 50 people an apple a day and 50 more no apples, then see at the end if those who ate them have kept the doctor away. Okay, most such trials are more sophisticated than that, and must be designed to exclude other possible causes; but experiments like this are the basis of science.

[snook]

Trial and error. If a course of action has been seen to be effective in preventing an illness many times, then one can assume that that course of action is a proven preventative measure.

You're right though - we do tend to underestimate the innate power of the body to heal itself. Can't remember who it was who said a physician's job was to make the patient comfortable while Nature did the healing.

[jake-the-peg]

They do double blind tests.

Two groups of people with similar afflictions, one group get the real drug one group gets a sugar pill (placebo).

Even the doctors don't know which has which only that patient A has treatment 1 and Patient B has treatment 2.

Then they evaluate who's got better, who's a bit better and who's worse etc. Then they open the envelopes and find out who had what treatment. If the treatment's effective there should be a statistically significant difference between the two groups.

The pacebo's important because people really do get better if they think they're getting effective treatment. there have been the most amazing trials with *fake* surgery giving people with artharitis the ability to walk again. It's even been shown that large red sugar pills are more effective than small blue ones.

[The Tree]

jake.i know how they do trial tests with drugs.what i was wondering was how do they know for example that green tea can prevent cancer cells from forming.cause if you drink green tea and dont get cancer was it the green tea or did you just not get cancer.

[jake-the-peg]

Ah well I don't think things like green tea have usually been tested with the same rigour.

I think the logic goes that things like anti-oxidents are known to help prevent cancers from lab work (oxidising chemicals can trigger cancers and anti-oxidants mop these up). Things like green tea have a lot of anti-oxidants therefore green tea can stop cancers.

It may well be true but it maybe there's a complexity that stops this from working that way. But if you're doing a magazine article or a 2 minute health spot on Richard and Judy you're not going to worry about that!

That's a specific case but I'd reckon if you dig deeply enough most similar claims are based on logic like that rather than actual trials.