Pomegranate: benefits, dosage, contraindications

Antioxidant

The main antioxidants found in pomegranate are polyphenols: anthocyanins, tannins and ellagic acid. These substances are potent inhibitors of LDL (low-density lipoprotein) oxidation and are avid scavengers of reactive oxygen species that are generated both intra- and extracellularly. Pomegranate juice contains about 1.5% by weight of flavonoids, polyphenols, pectin and ascorbic acid. The content of soluble polyphenols ranges between 0.2 and 1%, and consists mainly of anthocyanins. Furthermore, in in vivo and in vitro studies, extracts from the peel, seeds, flowers, leaves and pulp also possess antioxidant activities. It should be noted that the antioxidant activity of pomegranate juice has been compared to that of red wine or green tea, and appears to be 2 to 3 times higher. Pomegranate juice has shown in vitro beneficial effects on nitric oxide levels, probably due to its antioxidant protective effects and to the enhancement of the bioactivity of nitric oxide synthase (NOS). Nitric oxide synthase increases the availability of nitric oxide, an antioxidant and a vasodilator.

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Anti-inflammatory

Pomegranate has powerful anti-inflammatory properties, which are largely mediated by its antioxidant properties. In human research, the anti-inflammatory effects of pomegranate extract have been associated with beneficial changes in the gut microbiota. These effects are likely due to the regulation of inflammatory proteins and the suppression of inflammatory mediators. They include — among others — inhibition of cyclooxygenase (COX) activity, lipoxygenase activity, nitric oxide (NO) production, and inhibition of nuclear factor kappa B (NF-kappaB) transcription factor activity.

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Anticancer

Preliminary clinical research suggests that pomegranate may have a role in preventing certain cancers such as prostate cancer and breast cancer. Pomegranate fruit extracts inhibit cell growth and induce apoptosis of aggressive prostate cancer cells in vitro.nnPomegranate fruit extracts also appear to reduce prostate-specific antigen (PSA) levels in animals implanted with prostate cancer cells; and to inhibit tumor growth, angiogenesis, and metastasis in animal studies. nnPolyphenols from fermented pomegranate juice and other pomegranate extracts are active against malignant breast cancer cells. In vitro and animal studies show that pomegranate constituents can inhibit cell proliferation and metastasis in breast cancer. nnPomegranate seed oil also appears to have activity against skin cancer cells. Furthermore, pomegranate polyphenol fractions exert actions through their antiproliferative, apoptotic, antiangiogenic, antioxidant, and possibly anti-inflammatory effects. nnAccording to epidemiological research, urolithin glucuronides and ellagic acid found in pomegranate may be responsible for the effects against prostate cancer. These studies also showed that combinations of pomegranate extracts from different parts of the fruit were more effective than a single extract.

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Antimicrobial

The antibacterial and antifungal effects of pomegranate may potentially be protective against infections and inflammation of the mouth, including gingivitis, periodontitis, and denture stomatitis.

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Antiparasitic

Some in vitro and in vivo research suggests that pomegranate extracts have potential antiparasitic activity against adult worms of Schistosoma mansoni. Other in vitro, but not in vivo, studies have demonstrated antiparasitic and antimalarial effects of the pomegranate fruit rind, in part by inhibiting plasmepsin-2 (an enzyme that degrades hemoglobin from Plasmodium, the parasites that cause malaria).

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Dermatological effect

Some preliminary research suggests that pomegranate has an anti-aging effect on the skin. An extract of pomegranate peel could inhibit matrix metalloproteinase-1 (MMP-1, enzymes capable of breaking peptide bonds in collagen), which destroys collagen in aged skin, and increase procollagen production activity by dermal fibroblasts. Pomegranate seed oil appears to stimulate the proliferation of keratinocytes (cells that make up 90% of the outer layer of the skin and skin appendages). In vitro, pomegranate extract led to an increase in collagen synthesis and a decrease in MMP-1 expression after UVB treatment of skin fibroblasts. Protective effects against UVA and UVB toxicity have been demonstrated in vitro.

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Cardiovascular

Epidemiological evidence suggests that the cardioprotective properties of fruits such as pomegranate may be partly due to their polyphenol content. nnIn animals, pomegranate fruit reduces enzymes that are markers of lipid peroxidation. nnPreliminary clinical evidence suggests that pomegranate may modestly improve cholesterol in some patients. Indeed, pomegranate juice may reduce cholesterol thanks to its polyphenolic constituents. In addition, pomegranate leaf contains tannins. These are thought to have anti-hyperlipidemic effects, possibly by inhibiting pancreatic lipase and by reducing energy intake.nnMoreover, a clinical study with pomegranate seed oil demonstrated a beneficial, but limited, effect on hyperlipidemic subjects.nn

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Antifungal

Preliminary clinical research suggests that pomegranate may act as a topical antifungal for the treatment of candidiasis associated with denture stomatitis, although the mechanism of action is unclear. In vitro research shows that pomegranate peel exhibits antifungal activity against two strains of Aspergillus parasiticus, Aspergillus flavus, Aspergillus ochraceus and Candida albicans. This antifungal activity is thought to be due to a peptide from the pomegranate peel. Clinical and in vitro research suggests that pomegranate may be effective against Trichomonas vaginalis (a human parasite responsible for a sexually transmitted infection, most often benign).

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Antihypertensive

Researchers studied the effect of consuming pomegranate juice (50 mL, 1.5 mmol total polyphenols per day, for 2 weeks) by hypertensive patients on their blood pressure. A 5% reduction in systolic blood pressure was observed.

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Antiviral

Preliminary research suggests that pomegranate juice may have activity against HIV, the influenza virus, and herpes simplex-2 (HSV-2). The polyphenol punicalagin appears to be the active constituent against influenza, probably due to its ability to modify the glycoproteins of the viral envelope. Pomegranate extracts rich in polyphenols appear to act synergistically with Tamiflu (a prescription antiviral).

Wound healing

In vivo tests in animals have shown the wound-healing properties of pomegranate peel and flower extracts. An ointment based on methanolic extract of pomegranate peel significantly improved wound contraction and the healing period, as evidenced by contraction rates, tensile strength, and increased synthesis of collagen, DNA, and proteins. These findings were supported by the methanolic extract's effectiveness as an antimicrobial and antioxidant.

Fertility effects

In animal studies, pomegranate juice increased sperm concentration and motility, the density of spermatogenic cells, the diameter of seminiferous tubules, and the thickness of the germ cell layer, and decreased the rate of abnormal sperm. The mechanisms of action may include antioxidant effects. Furthermore, some clinical studies suggest that daily consumption of pomegranate juice could improve erectile function in men with atherosclerosis. However, these results could not be confirmed in men with mild to moderate erectile dysfunction.

Neurological

Some animal research shows that pomegranate juice reduces soluble β-amyloid accumulation and amyloid deposition in the hippocampus, which suggests a potential role in Alzheimer's disease. As a reminder, the concurrent presence of β-amyloid aggregates and tau protein are the characteristic signs of Alzheimer's disease. It is suggested that pomegranate peel extract and pomegranate juice may have neuroprotective effects, possibly due to their hypoglycemic and antioxidant properties.

Antiplatelet agents/Anticoagulant

Preliminary in vitro research suggests that pomegranate fruit extracts, mainly ellagic acid, may have a potential role in regulating various pathophysiological processes involving thrombin (or thrombin-like protease).nn

Gastroprotective

Animal and in vitro studies suggest that pomegranate and its extracts have gastroprotective effects, most likely due to anti-inflammatory and antioxidant activity.nnOther animal research shows that pomegranate juice prevents intestinal histopathological changes after infection with Aeromonas hydrophila.nn

Hepatoprotective

In an animal model of diabetes and obesity, pomegranate flower extract reduces liver weight, as well as triglycerides and hepatic lipids.nn