Most people are familiar with pomegranates, those tough-skinned, globular fruits with delicious, crimson seeds. In addition to their popularity as Christmas stocking stuffers, pomegranates have gained a reputation for possessing significant health benefits. Although some of pomegranate's salutary properties are supported by scientific evidence, others are not. While researchers sift the data, supplement manufacturers are taking advantage of pomegranate's newfound celebrity.
Pomegranate has been ascribed with anti-inflammatory, antioxidant, anti-tumor and antiviral activities. Its effects in various cancers, metabolic diseases and fetal development have been explored. These properties could be better exploited if they were better characterized, but much more research is needed before pomegranate's full potential in human health can be determined. It is not clear at this time which form of pomegranate -- fresh juice, whole fruit or fractional extract -- is best for a given condition.
Ellagic Acid Significance
Pomegranate is a rich source of flavonoid antioxidants, including ellagic acid, a substance that is also found in blackberries, strawberries, cranberries, walnuts and pecans. Ellagic acid has been credited with many of pomegranate's medicinal properties, and pomegranate extracts containing up to 90 percent ellagic acid are commercially available. While this molecule may, indeed, be responsible for pomegranate's reputed health benefits, at least one study, published in "Journal of Medicinal Food" in 2004, demonstrated that different pomegranate extracts exert greater or lesser effects on selected cellular behaviors. This implies that some preparations may be better suited for specific applications than others.
Speculation
Women who have breast cancer are frequently prescribed medications that interfere with an enzyme called aromatase. Aromatase converts testosterone and other male hormones to estrogen, which ultimately makes some breast tumors grow faster. A 2010 article in "Cancer Prevention Research" showed that several compounds derived from pomegranate can also inhibit aromatase, but this activity differed from one compound to the next. Hence, pomegranate's usefulness for women who have or who are at risk for breast cancer is uncertain.
Potential
Experiments performed in animals and test tubes have shown that pomegranate extract inhibits the growth of prostate cancer cells, but it is uncertain if this property will translate to real benefit for men with prostate cancer. A 2005 trial published in "European Urology" demonstrated that the effects of chemotherapy in men with advanced prostate cancer were lessened by supplementation with ellagic acid, but there was no improvement in survival for study subjects. Another study in "Clinical Cancer Research" showed that consumption of pomegranate juice may delay the progression of prostate cancer in men, but this study was not placebo-controlled.
Cardiovascular Benefits
Several studies have demonstrated that pomegranate extracts can decrease total and LDL cholesterol levels in humans, and one 2004 trial in "Clinical Nutrition" showed that pomegranate juice reduced the severity of arterial thickening among people with atherosclerosis, or hardening of the arteries. Such findings are promising, but the scientists who conducted these studies conceded that further investigation was warranted.
Antimicrobial Properties
Ellagitannin, the form of ellagic acid found in pomegranates and other plants, is a potent antimicrobial agent. This property is undoubtedly of some evolutionary advantage to plants, but ellagitannin and its derivatives have not yet been thoroughly tested for their antibacterial and antiviral effects.
Considerations
Pomegranate juice and pomegranate extracts may be of significant use in human health, but more scientific evidence is needed before widespread use can be recommended. The effects of consuming large doses of pomegranate's active components over long periods of time are unknown. Consumption of significant amounts of pomegranate juice carries the additional burden of excessive sugar intake, which has implications for diabetics and people who are concerned about their weight. Finally, pomegranate has been shown to interfere with the metabolism of some prescription drugs, such as Coumadin, or warfarin. This could contribute to dangerous bleeding episodes in people who take this medication.
References
- "Journal of Medicinal Food"; Differentiation-Promoting Activity of Pomegranate (Punica Granatum) Fruit Extracts in HL-60 Human Promyelocytic Leukemia Cells; S. Kawaii, E. Lanky; 2004
- "Cancer Prevention Research"; Pomegranate Ellagitannin--Derived Compounds Exhibit Antiproliferative and Antiaromatase Activity in Breast Cancer Cells In Vitro; L. Adams et al.; 2010
- "European Urology"; Support Ellagic Acid Therapy in Patients With Hormone Refractory Prostate Cancer (HRPC) on Standard Chemotherapy Using Vinorelbine and Estramustine Phosphate; M. Falsaperla et al.; 2005
- "Clinical Cancer Research"; Phase II Study of Pomegranate Juice for Men With Rising Prostate-Specific Antigen Following Surgery or Radiation for Prostate Cancer; A. Pantuck et al.; 2006
- "Clinical Nutrition"; Pomegranate Juice Consumption for 3 Years by Patients With Carotid Artery Stenosis Reduces Carotid Intima-Media Thickness, Blood Pressure and LDL Oxidation; M. Aviram et al.; 2004
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