Effects of ω-3 Fatty Acids and Catechins on Fatty Acid Synthase in the Prostate: A Randomized Controlled Trial

ABSTRACT

Animal and human studies suggest fish oil and green tea may have protective effect on prostate cancer. Fatty acid synthase (FAS) has been hypothesized to be linked to chemoprotective effects of both compounds. This study evaluated the independent and joint effects of fish oil (FO) and green tea supplement (epigallocatechin-3-gallate, EGCG) on FAS and Ki-67 levels in prostate tissue. Through a double-blinded, randomized controlled trial with 2 × 2 factorial design, 89 men scheduled for repeat prostate biopsy following an initial negative prostate biopsy were randomized into either FO alone (1.9 g DHA + EPA/day), EGCG alone (600 mg/day), a combination of FO and EGCG, or placebo. We used linear mixed-effects models to test the differences of prostate tissue FAS and Ki-67 by immunohistochemistry between pre- and post-intervention within each group, as well as between treatment groups. Results did not show significant difference among treatment groups in pre-to-post-intervention changes of FAS (P = 0.69) or Ki-67 (P = 0.26). Comparing placebo group with any of the treatment groups, we did not find significant difference in FAS or Ki-67 changes (all P > 0.05). Results indicate FO or EGCG supplementation for a short duration may not be sufficient to produce biologically meaningful changes in FAS or Ki-67 levels in prostate tissue.

Acknowledgments

The authors would like to thank all the men who contributed their time and effort to join our study (Catechins and omega-3 Fatty Acids Impact on Fatty Acid Synthase Activity in the Prostate: a Randomized Controlled Trial) as well as those who expressed strong interest but who, for many reasons, were not able to participate. Sabinsa Corporation® (Piscataway, NJ) generously donated the green tea and green tea placebo capsules. Fish oil was manufactured by DSM® Nutritional Products Inc. (Parsippany, NJ), and the provision of the fish oil placebo along with the fish oil encapsulation was prepared by Perfect Source® Natural Products Inc. (Fullerton, CA). The authors are eternally grateful to the OHSU pathologists, Drs. Christopher Corless and George Thomas, who scored the immunohistochemistry slides and the OHSU surgical urologists, Drs. Christopher Amling and Mitchell Sokoloff, for subject recruitment. Ms. Laura Peters, Portland VA Medical Center urology nurse extraordinaire, has been an invaluable and indispensable honorary member of our study team for the life of this project (and other prostate health projects) and graciously assisted with subject retention and specimen collection. Thanks go to laboratory technical assistance from Dr. Dennis Koop, Lisa Blyele, and Karyn Foster at the OHSU BioAnalytical Shared Resource and PharmacoKinetics Core Laboratory as well as tissue staining assistance from Jutta Deininger and Cara Poage at the OHSU Knight Cancer Institute Cancer Pathology Shared Resource. The authors thank Solange Mongoue-Tchokote for providing statistical analyses assistance. The authors also appreciate Dr. Shannon's current and previous research coordinators who spent time with this study's subjects and worked with OHSU, KPNW, and PVAMC surgical urologists—Amy Palma, Gretchen Luhr, Alysia Cox, and Courtney Maxcy.

Declaration of interest

The authors report no conflict of interest in this study.

Funding

This study was supported by the Department of Defense (W81XWH0410296), the National Center for Complementary and Alternative Medicine (5R21AT003461), and the National Cancer Institute Cancer Center Support Grant (5P30CA069533); Clinical Trial Registration: clinicaltrials.gov identifier: NCT00253643.