Zinc from supplements associated with reduced risk of advanced prostate cancer

The March, 2009 issue of Nutrition and Cancer published the finding of Seattle's Fred Hutchinson Cancer Research Center of an association between long term consumption of zinc supplements and a reduced risk of advanced prostate cancer in men.

Prostate tissue contains ten times the level of zinc than other soft tissues in the body, while adenocarcinoma cells from prostate tumors lose the ability to concentrate the mineral. These and other factors led Emily White and colleagues to hypothesize that prostate cancer risk could be lowered by increased zinc intake. For the current study, they evaluated data from 35,242 men between the ages of 50 to 76 who participated in the VITamins and Lifestyle (VITAL) study of the impact of dietary supplements on cancer risk. Questionnaires completed upon enrollment provided information concerning diet and nutritional supplement intake over the past ten years, as well as demographic characteristics and health history. Eight hundred thirty-two of these participants developed invasive prostate cancers over a four year follow-up period, categorized as local, regional or distant invasion.

Zinc from diet or diet plus supplements was not found to be associated with prostate cancer risk. While a weak relationship was observed between a reduced risk of all invasive prostate cancers and long term supplementation with more than 15 milligrams zinc per day, the risk of advanced prostate cancer was significantly lower among subjects who reported supplementing with this amount of zinc.

In their discussion of the findings, the authors note their observation of a greater reduction in the risk of prostate cancer associated with zinc among those in this study whose vegetable intake was high, which suggests that supplementing with zinc could be of benefit to those whose absorption of the mineral is impaired due to increased phytate intake from plant foods.

"If future studies support these results, it may suggest that zinc supplements may be beneficial for some subgroups of men for the most adverse forms of the disease," the authors conclude.