Pomegranate juice has created a stir among medical researchers. There have been multiple clinical trials to explore its benefits in men with prostate cancer, including those who have a rising PSA after initial treatment.
Pomegranate juice has high levels of antioxidants including:
- Polyphenols — which are natural antioxidant compounds that are also found in green tea
- Isoflavones — which you can also find in soy products
- Ellagitannins — which are bioactive polyphenols that are also in strawberries, walnuts, and some wines. Ellagitannins are broken down to ellagic acid, a substance that researchers believe may play a role in killing cancer cells
Antioxidants are beneficial because they may prevent the risk of cancer by blocking the actions of free radicals that have been associated with causing cell damage.
Extract of this fruit also contains three anthocyanidins (delphinidin, cyanidin, and pelargonidin) that researchers believe contribute to its antioxidant activity.
In particular, delphinidin has shown promise as a potential cancer-fighting agent in several laboratory studies.
Pomegranate juice: Human studies
An excellent review article by Wang et al provides a great overview of human studies investigaing pomegranate juice (PJ), including:
- A phase II clinical trial (Paller et al) of men with advanced prostate cancer who had a rising PSA received 1 g (comparable to about 8 oz of PJ) or extracts for up to 18 months. PSA doubling time lengthened more than 6 months from 11.9 to 18.5 months (p < 0.001) with no significant difference between groups. But no man developed metastases during the trial period
- A phase II study (Pantuck et al) of men who had a PSA rise after surgery or radiation (detectable PSA > 0.2 and < 5 ng/mL; Gleason score < or = 7). The mean PSA doubling time significantly increased in men who drank 8 ounces of PJ daily from 15 months at baseline to 54 months after treatment
- Wang et al have demonstrated in laboratory studies that in addition to causing cell death of hormone-refractory prostate cancer cells, PJ also increases cell adhesion and decreases cell migration of the cells that do not die
- Malik et al demonstrated in an animal study that the fruit extract possessed antitumor-promoting effects in mouse skin
- In laboratory studies, Hong et al demonstrated that pomegranate extracts inhibited both androgen-dependent and androgen-independent prostate cancer cell growth. Inhibited gene expression involved in androgen-synthesizing enzymes was also demonstrated
- Rettig et al have demonstrated that the fruit extract inhibited androgen-independent prostate cancer growth through a nuclear factor-kappaB-dependent mechanism
Hong MY, Seeram NP, Heber D. Pomegranate polyphenols down-regulate expression of androgen-synthesizing genes in human prostate cancer cells overexpressing the androgen receptor. J Nutr Biochem. 2008;12:848-55.
Malik A, Afaq F, Sarfaraz S, Adhami VM, Syed DN, Mukhtar H. Pomegranate fruit juice for chemoprevention and chemotherapy of prostate cancer. Proc Natl Acad Sci USA. 2005;102(41):14813-8.
Noda Y, Kaneyuki T, Mori A, Packer L. Antioxidant activities of pomegranate fruit extract and its anthocyanidins: delphinidin, cyanidin, and pelargonidin. J Agric Food Chem. 2002;50(1):166–171
Pantuck AJ, Leppert JT, Zomorodian N, et al. Phase II study of pomegranate juice for men with rising prostate-specific antigen following surgery or radiation for prostate cancer. Clin Cancer Res. 2006;13:4018-26.
Rettig MB, Heber D, An J, Seeram NP, et al. Pomegranate extract inhibits androgen-independent prostate cancer growth through a nuclear factor-kappaB-dependent mechanism. Mol Cancer Ther. 2008;7(9):2662-71.
Wang L, Alcon A, Yuan H, Ho J, Li QJ, Martins-Green M. Cellular and molecular mechanisms of pomegranate juice-induced anti-metastatic effect on prostate cancer cells. Integr Biol (Camb). 2011 May 19. [Epub ahead of print]