In July and August, I wrote about recently published studies on multivitamins and mortality and fish oil and atrial fibrillation. My criticism of those observational studies was because the analyses of the data were incomplete, in my opinion. Here’s how the study we just finished on quercetin and irritable bowel did the correct analysis.

Researchers focused on the subjects with an irritable bowel condition and examined a single nutrient. They already knew that increased fruit and vegetable intake benefitted people with irritable bowels; they specifically examined the quercetin content of those vegetables and fruit to see if subjects who ate those foods needed fewer enterotomies and had lower mortality. They did. This is the way nutrition research should be done.

That’s exactly what they did not do in the multivitamin and fish oil studies. It isn’t like they didn’t have the data; one of the studies used the exact same database of subjects with the nutrition data already collected. They could have analyzed by nutrient, whether it was a macronutrient such as protein, carbohydrate, and fat; by the source of the protein, fat, and carbohydrate intake; or by specific nutrients such as calcium, beta-carotene, or type of fish oil. I could go on, but the point is they could have done more. But as I suggested, when physicians and statisticians are the only experts used—without nutritionists and dieticians—they apparently didn’t know the correct questions to ask.

As a result, we’re now stuck with physicians and other healthcare professionals questioning the use of multivitamins and fish oil. Experience tells me that will be hanging over our heads for years.

During the conclusion and recommendation section of every study, they always finish the observational studies with something like “This study doesn’t provide cause and effect; we need randomized controlled trials to test these findings.” I submit we need more thoughtful analysis of the data used in these studies. The way I see it, those studies were disasters, and there are more to come in the near future. Next week we’ll look at a study that condemns green tea extract and turmeric.

What are you prepared to do today?

        Dr. Chet