Monday, 25 June 2007

Why we shouldn't be concerned about negative results from clinical trials

During my long research about nutrition, I often come across clinical trials that tell us that anti-oxidants and other nutrients are useless or does not cause disease to regress. And those trials seem to be valid -- they are the "golden standard" for clinical trials after all: randomized, placebo controlled clinical trials. But as this article argues, clinical trials may not be the best gauge of the effectiveness of nutrients, especially when they are individually tested (like drugs) or when they are used to cure disease, rather than prevent them.

Click here for the whole article.

Randomised clinical trials are the ultimate. Forget what the observational studies tell us, if the RCT gives us an answer it must be the final word, right? Wrong.

The value of such trials for the food industry is undeniable, but too often nutrients are pulled out of context, following the same methodology as used for the testing of drugs.

But let's not forget that by following the drug model we are supplementing the diet with one or two nutrients, each at a single dose, for a set period of time. Can a time-constrained randomised trial really capture a lifetime of consumption with respect to chronic disease?

Despite a vast body of observational/ epidemiological studies linking an increased dietary intake of antioxidants from fruits and vegetables to reduced risks of a range of disease, including cancer, cardiovascular disease and diabetes, when such antioxidants have been extracted and put into supplements, the results, according to RCTs, do not produce the same benefits and may even be harmful.

So the author of the article, Dr. Lisa Melton from the London-based registered charity, the Novartis Foundation, concluded that antioxidant supplements are too good to be true.

It certainly begs these questions:

Is this really the answer or is it due to poor study design? Would a two-year trial of vitamin E, let's say, really produce a reduction in the risk of a chronic disease?

The answer is probably "no" or "negligible." The design was flawed from the start. No wonder population-based studies often clash with clinical trials.

Besides, we have to consider that not all supplements are created equal. If the supplements used were sub-standard, then disappointing results really shouldn't come as a surprise.

I think that if only the scientific community will agree that nutrients should be tested differently, perhaps with more consideration to their nature that nutrients work over time and that they work in synergy (with other nutrients) then we would get a clearer and more encouraging results.

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