Before its recent explosion into the mainstream of commercial health foods, pomegranate was a little-known fruit in much of North America. Pomegranate has an ancient history and is mentioned in Egyptian and Greek literature as well as the Old Testament, Jewish Torah, and the Babylonian Talmud.1 Some historians even believe that the pomegranate tree flourished in the Garden of Eden.2 Many of these historic writings refer to the pomegranate as a sacred fruit capable of inducing fertility, wealth, and good luck.1

Background

The pomegranate can measure up to 5 in wide and has a dark, leathery skin.1 Perhaps its best-known feature is its unique seed formation. The pulpy white flesh of the pomegranate is full of septated lobules that are laden with seeds. Each seed is coated with a thin layer of juice-bearing membrane.1

Most of the pomegranate’s medicinal value comes from its juice. Among its abundance of antioxidants, the category known as acanthocyanins is the largest and most bioactive.1

Science

Pomegranate juice is credited with a wide range of therapeutic uses. Research to date has focused on antioxidant activity, anticarcinogenic potential, and anti-inflammatory effects.1

It is a well-established fact that vitamin C and other similar oxygen free-radical scavengers reduce cell wear and tear and increase the body’s protective mechanisms. One pomegranate also contains nearly 50% of an adult’s total daily requirement of vitamin C, more than 10% that of magnesium and folate, and 27% of daily potassium.3, 4 These plus a cascade of other potent polyphenol antioxidants are believed responsible for pomegranate’s health effects. Pomegranate juice possesses two to three times the antioxidant capacity of red wine or green tea.1

As an anticancer agent, pomegranate has unique potential. In one study, 46 men with Gleason scores (a method of prostate cancer tissue grading) 5-7 were given daily amounts of pomegranate juice.5 Their prostate-specific antigen (PSA) levels were tracked at three-month intervals from baseline and compared with pretreatment levels. The ideal endpoint was a reduction in or flattening of the PSA doubling time (PSADT) curve.5 At the end of the two-year trial, 83% of participants showed an improvement in PSADTs, with three patients actually showing a decrease in PSA5.

The anticancer properties of pomegranate seem to be interrelated with its antioxidant and anti-inflammatory effects. There are strong supporting data indicating that inflammation and oxidative damage promote cancer-cell growth. Since pomegranate juice is highly effective against both of these processes, the assumption can be made that these effects are responsible for the anticancer activity.

In another study, patients with known coronary artery disease were given pomegranate juice or placebo daily for three months.6 The treatment group showed a drop in stress-induced ischemia compared with an increased score in the placebo group.6

In a third trial, 10 patients with atherogenic carotid artery stenosis were treated with daily pomegranate juice for a minimum of one year and up to five years.7 Progression of disease was gauged by ultrasonic measurement of arterial intimal thickness.7 The intimal thickness in the control group increased by 9% in one year, but the treatment group showed a reduction of up to 30% in the same time period.7

Plaque formation creates irregularities in blood flow patterns, often called turbulence.8 These multiple whirlpools of blood flow increase the stress on the intimal vascular wall, perpetuating the inflammatory process.8 Pomegranate increases the expression of nitric oxide as a protective agent against this damage.8

Safety, drug interactions

Significant allergic reactions to pomegranate juice have been reported. Angioedema with airway distress has been noted.9 Pomegranate can interfere with the breakdown of other medications, specifically statins. As a potent stimulant of uterine contraction, pomegranate is definitely unsafe for use during pregnancy.3 Due to its high potassium content, persons with renal insufficiency or those taking medications that increase serum potassium (e.g., ACE inhibitors) should also exercise caution.3

Dose, how supplied, and cost

Most studies focus on a daily intake of 30-60 ml of pomegranate juice per day for two to five weeks.3 An 8-oz bottle costs $4-$6. Gel- and powder-filled capsules cost an average of $25 for a one-month supply.

Summary

Given our current predilection to highly inflammatory, atherogenic habits, a balance as powerful as pomegranate is welcome. With proper caution, clinicians can recommend this product as a weapon in the arsenal against oxidative damage that impacts literally every cell in the body. n

References

1. Jurenka JS. Therapeutic applications of pomegranate (Punica granatum L.): A review. Altern Med Rev. 2008;13:128-144.

2. Louba, B. What are the medical properties of pomegranates? J Chinese Clin Med. 2007;9:530-538.

3. Natural Standard Monograph (2010). Pomegranate (Punica granatum) Natural Medicines Comprehensive Database. Natural Standard, Inc.

4. United States Department of Agriculture (2009). Pomegranate: SR-21.

5. 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;12:4018-4026.

6. Sumner, MD, Elliott-Eller M, Weidner G, et al. Effects of pomegranate juice consumption on myocardial perfusion in patients with coronary heart disease. Am J Cardiol. 2005;96:810-814.

7. Aviram M, Rosenblat M, Gaitini D, et al. Pomegranate juice consumption for 3 years by patients with carotid artery stenosis reduces common carotid intima-media thickness, blood pressure and LDL oxidation. Clin Nutr. 2004;23:423-433.

8. de Nigris F, Williams-Ignarro S, Lerman LO, et al. Beneficial effects of pomegranate juice on oxidation-sensitive genes and endothelial nitric oxide synthase activity at sites of perturbed shear stress. Proc Natl Acad Sci USA. 2005;102:4896-4901.

9. Igea J, Cuesta J, Cuevas M, et al. Adverse reaction to pomegranate ingestion. Allergy. 1991;46:472-474.

All electronic documents accessed February 15, 2010.