Archive for May, 2007

Vitamins and Prostate Cancer

Wednesday, May 16th, 2007

I am amazed by the number of poorly conducted studies that get published. Today I am aware of another study whose design would fail a Fourth Grade Science Fair. The Journal of the National Cancer Institute has just published a study that supposedly links consistent higher dose multivitamin use in AARP men at a medin age of 63 years-old to an increased rate of prostate cancer over 5 years. Nearly 30 thousand men participated in this survey driven study. Nearly 1/3 of the participants supposedly “developed” prostate cancer over the five years. I say supposedly, since the criteria for “prostate cancer free” was based on reported “normal” PSA and digital rectal exam within the last 3 years by the subject. As this study is released, another study is published by the Journal of Urology that shows that prostate cancer is under-diagnosed in up to 36% of men with PSA values from 2-10 ng/ml. This nearly equals the number of prostate cancers later detected in the multivitamin study. So the assumption that their subjects were cancer-free is inappropriate. This weakness in their study may have been minimized by having prostate ultrasounds, and biopsies if indicated.

The next weakness in this study, that the authors also failed to mention, is that WE ARE WHAT WE ABSORB AND METABOLIZE, not what we eat. Some people can eat many vitamins, foods, and still be under nourished and vitamin deficient. The study coordinators did not assess vitamin metabolism or prostate tissue or immune system nutriture. My patients benefit from individualized health assessments that include Spectracell’s comprehensive leukocyte nutriture testing. In this way they have a much better idea about the vitamin deficiencies in their immune system. The subjects of this study did not have this included in the survey. This study was filled with assumptions.

They noted a correlation with prostate cancer aggressiveness with increased zinc intake. Again, the authors missed important concepts in nutrition. Zinc and vitamin A have a balance. High levels of zinc can deplete vitamin A. Furthermore, low serum levels of zinc and vitamin A have both been noted in patients with prostate cancer. So the survey-oriented study did not address this adequately either. Did the zinc get metabolized and deplete another necessary nutrient, vitamin A? Were these subjects still low in zinc despite ingestion? Did the zinc act as an aromatase inhibitor that indirectly increased 5 alpha reductase activity and elevated dihydrotestosterone levels? (That’s another important factor that went completely unaddressed!)

I am disappointed in the NIH for financing such a poorly constructed study. This study has not shown us that vitamin use is a problem, but rather that the health care system needs to assess nutriture status through tissue testing, metabolic analysis and that prostate cancer risk assessments need to include better diagnostic methods like prostate ultrasound, nutrition and hormone testing.

References:

Lawson K, Wright M, Subar A, Mouw T, Hollenbeck A, Schatzkin A, Leitzmann M. Multivitamin use and risk of prostate cancer in the National Institutes of Health-AARP Diet and Health Study. Journal of the National Cancer Institute. Vol 99, No. 10. pp754-764.

Pelzer AE, Bektic J, Akkad T, Ongarello S, Schaefer G, Schwentner C, Frausher F, Bartsch G, Horninger W. Under diagnosis and over diagnosis of prostate cancer in a screening population with serum PSA 2 to 10 ng/ml. Journal of Urology 2007 May 10. (Epub ahead of print).

Ozmen H, Erulas FA, Karata F, Cukurovali A, Yalcin O. Comparison of the concentration of trace metals (Ni, Zn, Co, Cu ans Se), Fe, vitamin A, C and E, and lipid peroxidation in patients with prostate cancer. Cin Chem Lab Med 2006;44(2):175-9.