Canadian Researchers Say Prostate Health Supplements 'VaryWidely' in Measured Dose

TORONTO--Commonly used nutritional supplements for prostatedisease vary widely in measured dose, according to an analysis conducted byresearchers at the Toronto-Sunnybrook Regional Cancer Centre. Results of theirstudy, which are available online (www.jurology.com),were published in the July issue of The Journal of Urology (168, 1:150-4,2002). Researchers purchased samples of several brands of vitamin E, vitamin D,selenium, lycopene and saw palmetto at pharmacies and specialty stores, and sentthem for independent chemical analysis. The measured dose was compared to thestated dose on the product label, and analysis of variance was performed to testfor significance in interlot reliability.

Results indicated that all of the products varied in their specified dose andactual dose, although saw palmetto products fared the worst. The six sawpalmetto samples were within a range of -97 percent to 140 percent of the stateddosages, with three containing less than 20 percent of the stated dosages.Lycopene samples didn't test much better. Lycopene brands were between -38percent and 143 percent of stated dosages.

Researchers stated that the "more regulated substances," thevitamins and minerals, demonstrated less variation. The seven samples of vitaminE products and five samples of selenium products were within a range of -41percent to 57 percent and -19 percent to 23 percent of the stated dosage,respectively. All four vitamin D brands were within 15 percent of the stateddose.

Additional results indicated that there were statistically significantdifferences in interlot dosages for some of the supplements. Among thereliability assays, one of three brands of vitamin E, one of two brands ofselenium and one of two brands of saw palmetto demonstrated statisticaldifferences in interlot dosages (approximately 20 percent to 25 percentdifferences in dose). The one assayed form of vitamin D was reliable betweenlots.

Researchers concluded that the commonly used nutritional supplements forprostate disease vary widely between labeled and measured dosages. They notedthat saw palmetto demonstrated tremendous variability with some samplescontaining virtually no active ingredients, and, in contrast, the more regulatedsubstances that were measured--such as vitamins and minerals--demonstrated lessvariation.