Reviewed: 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.

Summary: In an open label, parallel group clinical trial, 19 patients (5 women and 14 men, aged 65-75 years) with severe carotid artery stenosis (CAS) were selected to receive 50 ml concentrated pomegranate juice (PJ) containing 1.5 mmoles of polyphenols per day, the equivalent of 8.3 oz (250 ml) of 100% juice (treatment group; n = 10) or no PJ (control group; n = 9). The CAS was measured at 70-90% occlusion of the internal carotid arteries as confirmed by Doppler ultrasound. The PJ was prepared from the crushed fruit of hand-picked pomegranates and was filtered, pasteurized, concentrated, and stored at –18 C. The concentrated PJ was diluted with water to obtain a single strength juice.

The antioxidant composition of the juice was measured as follows: 1978 mg/l tannins (1561 mg/l punicalagins and 417 mg/l hydrolysable tannins), 384 mg/l anthocyanins (delphinidin 3,5-diglucoside, cyanidin 3,5-diglucoside, delphinidin-3-glucoside, cyanidin 3-glucoside, pelargonidine 3-glucoside), and 121 mg/l ellagic acid derivatives. The juice also contained 3 mg vitamin C per 100 ml juice. The study period lasted for 1 year, and 5 patients consuming PJ continued for another 2 years.

The primary outcome was the change in intima-media thickness (IMT) over time measured at the distal common carotid artery by Doppler ultrasound. IMT refers to the intima plus media layers of the carotid artery. IMT measures the distance between the lumen intima boundary (the space in which blood flows) and the media adventitia boundary (the outermost region of the artery). Additional outcomes included a range of cardiovascular parameters:

• peak systolic velocity (PSV);

• end diastolic velocity (EDV);

• total cholesterol;

• high density lipoprotein (HDL) cholesterol;

• triglycerides;

• apolipoproteins A-1 and B-100;

• serum paraoxonase 1 (PON 1) arylesterase activity, an HDL-associated enzyme that can reduce lipid peroxides, thereby decreasing oxidative stress;

• total antioxidant status;

• serum anti Oxidized low density lipoprotein (Ox-LDL) antibodies;

• LDL oxidation;

• total antioxidant status (TAS); and

• chemical analyses of atherosclerotic plaques obtained by endartherectomy for cholesterol, lipid peroxides, and reduced glutathione (GSH) concentrations.

Compared to pretreatment values, mean IMT decreased significantly in the treatment group after 3, 6, 9, and 12 months (–13%, –22%, –26%, and –35%, respectively; p < 0.01). After 12 months of treatment the mean IMT had decreased from 1.5 ± 0.2 mm at baseline to 1.1 ± 0.1 mm (p < 0.01) and remained at that approximate mean thickness for the duration of the study. In contrast, from baseline to 12 months, the mean IMT in the placebo group significantly increased from 1.52 ± 0.03 to 1.65 ± 0.04 mm, (p < 0.01). Significant decreases after 1 year of treatment were noted for mean PSV (cm/s), which decreased from 135 ± 6 to 103 ± 10 (p < 0.01), and for mean EDV, which decreased from 38 ±1 to 30 ± 12 (p < 0.01), with no additional significant reductions for the remainder of the trial.

Systolic, but not diastolic, blood pressure (mmHg) was significantly reduced after 1 month of treatment from 174 ± 8 to 162 ± 9 (p < 0.05); compared to baseline, blood pressure was significantly reduced even further after 12 months to 153 ± 7 (p < 0.01). Blood pressure was not significantly changed in the placebo group at any time period compared to baseline. Compared to baseline, anti-Ox-LDL antibodies (EU/ml) significantly decreased by 24% after 1 month of treatment and by 19% after 3 months (p < 0.01). Mean TAS (nmol/L) increased after 12 months of PJ consumption. However, one month after stopping PJ, mean TAS was found to decrease. Mean serum lipid oxidation (nmol lipid peroxides/ml) significantly decreased in the PJ group after 12 months of treatment (p < 0.01) and was found to further decrease after 28 months and 36 months compared to baseline (p < 0.01). PON 1 (U/ml) significantly increased in the treatment group after 1 year (p < 0.01) and continued to significantly increase at 3 years in those patients taking PJ for an additional 2 years (p < 0.01); however, one month after stopping PJ, PON 1 activity was found to decrease. LDL cholesterol isolated from patients showed that LDL-associated lipid peroxides were reduced by 90% after 6 months, and the susceptibility of LDL to copper ion induced oxidation was gradually and significantly decreased over the course of 1 year.

Carotid endarterectomy (surgery that removes harmful plaque from major arteries that carry blood to the head) was performed in two patients, one after 3 months and one after 12 months of consuming PJ, due to clinical deterioration during the trial. Compared to 7 controls, their carotid lesions had significantly lower mean concentrations of cholesterol (58% and 20% lower, respectively; p < 0.01), lipid peroxides (61% and 44%, respectively; p < 0.01), and lesion-induced LDL oxidation (43% and 32%, respectively; p < 0.01), and significantly higher reduced glutathione (2.5 times higher in both samples; p < 0.01). No adverse events were reported.

Comments/Opinions: The results of this very small study suggest that regular consumption of PJ is beneficial to persons with CAS. In addition to anti-atherosclerotic properties (as seen with the reduced common carotid IMT), the juice also appears to have significant antioxidant activity as noted by the decrease in LDL-oxidation and the significant increase in PON 1 activity. The increase in PON 1 activity was not only seen in the 10 patients consuming PJ at 1 year but was also found to continually increase over an additional 2 years in 5 patients. PON 1 is an interesting measure of lipid oxidation activity and has been found to decrease in persons with hypercholesterolemia, diabetes, and cardiovascular disease.^1,2 PON 1 is inactivated by oxidized lipids, and PJ appears to act like red wine flavonoids and licorice-derived glabridin to preserve PON 1 activity during lipid peroxidation.³ Another remarkable finding in this trial is the significant reduction in systolic blood pressure after 1 year of juice consumption.

Pomegranate (Punica granatum L., Punicaceae) likely originated in Iran and Afghanistan and is currently grown mainly in Iran, India, and the United States, but also in most Near and Far East Countries.⁴ Primarily used as a table fruit, it is also commonly used in the beverage and liquor industries. The pericarp, which is high in tannins, is also used for tanning leather.

Historically, the fruit is mentioned by various cultures and religions. The pomegranate tree is said to have flourished in the Garden of Eden (apparently sans a particular snake) and is very likely the “apple” of the Adam and Eve story in Genesis. Greek and Persian mythology mention the fruit as representing life, regeneration, and marriage.⁵ The ancient Chinese believed the seeds symbolized longevity and immortality. In Judaism, pomegranate seeds are said to number 613—one for each of the Torah’s 613 commandments. The fruit is also a symbol of resurrection and life in Christianity, and it is one of the three “blessed fruits” in Buddhism.

Most of the chemical analysis of pomegranate has focused on the juice, peel/pericarp, and seed oil. The juice/fruit contains high amounts of hydrolyzable tannins, in particular ellagitannins (gallic acid and ellagic acid), anthocyanins (cyanidin, delphinidin, pelargonidin), as well as the phenolic acids: ellagic acid, caffeic acid, and chlorogenic acid.^6,7 The pericarp is also high in hydrolyzable tannins.⁸ (Note: The pericarp is the skin surrounding the seed, really the “aril.” The seed is only the hard, white internal seed; the red juicy edible sacs, including the seed, are called arils.) Pressing the whole fruit results in juice that is much higher in the pericarp polyphenols. Luteolin, quercetin, kaempferol, and narigenin are also found in the peels. The seed oil consists of about 63.5% punicic acid—a rare trans 18-carbon fatty acid (structurally related to conjugated linolenic acid).⁴ According to one source, the seed also contains the highest concentration of estrone in the plant kingdom—approximately 17 mg/kg of dried seed.⁹ Interest has been growing in the past few years about the potential of pomegranate oil as a potent phytoestrogen and its potential cancer preventive properties, especially with regard to breast cancer.¹⁰

For the past several years, Israeli researchers, lead by Dr. Michael Aviram (Lipid Research Laboratory, Rappaport Family Institute for Research in the Medical Sciences, Rambam Medical Center, Haifa, Israel) have been focusing on the antioxidant properties of PJ as well as the potential cardiovascular benefits. In one study, pomegranate juice was found to reduce atherosclerotic lesion size in apolipoprotein E-deficient mice.¹¹ An ex vivo study with healthy male volunteers found that consumption of 50 ml of concentrated pomegranate juice per day (equal to 8 oz./day of 100% juice) reduced LDL susceptibility to oxidation and increased activity of serum paraoxonase (PON1).¹² Finally, a clinical trial found that consumption of 50 ml of concentrated pomegranate juice per day (equal to 8 oz./d of 100% juice) for 2 weeks resulted in a 36% decrease in serum angiotensin converting enzyme (ACE) activity and a 5% reduction in systolic blood pressure in 10 patients (age 62-77 years) with hypertension.¹³ The reviewed study with PJ is a continuation of their work and hopefully the beginning of new, exciting findings into the cardiovascular health benefits of pomegranate.

Practice Implications: Although the patient population is small in this new clinical trial, the results are impressive when considering the length of the study. Focusing on patients with CAS, the study supports previous findings that PJ possesses anti-atherosclerotic properties and also decreases systolic blood pressure. Hopefully, this study will result in larger trials focusing on the long-term cardiovascular benefits of PJ and will do a more thorough comparison statistically with a placebo group. The availability of encapsulated extracts of pomegranate also offers health care professionals alternatives to the juice for diabetic patients and those wishing to use a more concentrated form of pomegranate for prevention of cardiovascular disease. Hopefully, companies will develop standardized extracts that reflect the tannin and total polyphenol content critical to the cardiovascular benefits of PJ.

References:

1. Aviram M. Does serum paraoxonase play a role in susceptibility to cardiovascular disease? Mol Med Today. 1999;5:381–386.

2. Mackness MJ, Harty D, Bhantnagar D, et al. Serum paroxonase activity in familial hypercholesterolemia and insulin dependent diabetes mellitus. Atherosclerosis. 1991;86:193–199.

3. Aviram M, Rosenblat M, Billecke S, et al. Human serum paraoxonase (PON1) is inactivated by oxidized low density lipoprotein and preserved by antioxidants. Free Radical Biol. 1999;26:892–904.

4. Schubert SY, Lansky EP, Neeman I. Antioxidant and eicosanoid enzyme inhibition properties of pomegranate seed oil and fermented juice flavonoids. J Ethnopharmacol. 1999;66:11–17.

5. Langley P. Why a pomegranate? BMJ. 2000;321:1153–1154.

6. Artik N, Ceremroglu B, Murakami H, Mori T. Determination of phenolic compounds in pomegranate juice by HPLC. Fruit Process. 1998;8:492–499.

7. Gil MI, Tomas-Barberan FA, Hess-Pierce B, Holcroft DM, Kader AA. Antioxidant activity of pomegranate juice and its relationship with phenolic composition and processing. J Agri Food Chem. 2000;48:4581-4589.

8. Ben Nasar N, Ayed M. Quantitative determination of polyphenolic content of pomegranate peel. Z Lebensm Unters Frosch. 1996;203:374–378.

9. Heftmann E, Ko ST, Bennett RD. Identification of estrone in pomegranate seeds. Phytochem. 1966;5:1337–1340.

10. Kim ND, Metha R, Yu W, et al. Chemopreventive and adjuvant therapeutic potential of pomegranate (Punica granatum) for human breast cancer. Breast Cancer Res Treatment. 2002;71:203–217.

11. Kaplan M, Hayek T, Raz A, et al. Pomegranate juice supplementation to atherosclerotic mice reduces macrophage lipid peroxidation, cellular cholesterol accumulation and development of atherosclerosis. J Nutr. 2001;131:2082–2089.

12. Aviram M, Dronfeld L, Rosenblat M, et al. Pomegranate juice consumption reduces oxidative stress, atherogenic modifications to LDL, and platelet aggregation: studies in humans and in atherosclerotic apolipoprotein E-deficient mice. Am J Clin Nutr. 2000;71:1062–1076.

13. Aviram M, Dronfeld L. Pomegranate juice consumption inhibits serum angiotensin converting enzyme activity and reduces systolic blood pressure. Atherosclerosis 2001;158:195–198.

Dr. Brown would like to acknowledge John Neustadt, ND4, for his assistance in preparing the clinical summaries in this column.