If the hype is to be believed, just about everyone can benefit from drinking pomegranate juice. It’s touted as the natural answer to a laundry list of health problems-ranging from cancer and heart disease to diabetes and Alzheimer’s.
And although it all sounds too good to be true, in fact, there’s an impressive amount of scientific research on this tart-tasting drink. Studies show that the juice of this ancient fruit may well have many modern applications.
Cancer
Recent laboratory research has revealed that pomegranate juice and its components possess potent anticancer properties. In one study, presented in December, 2010, at the 50th annual meeting of the American Society for Cell Biology in Philadelphia, researchers from the University of California at Riverside demonstrated that pomegranate juice might stop prostate cancer from spreading.
The study, performed at the lab of Manuela Martins-Green, a professor of cell biology, identified a number of components in pomegranate juice-namely, phenylpropanoids, hydrobenzoic acids, flavones and conjugated fatty acids-that can both inhibit the growth of cancer cells and weaken their attraction to a chemical signal that promotes the metastasis (spread) of prostate cancer to the bone.
These exciting findings could lead to the development of new therapies for preventing prostate-cancer metastases, the researchers said. What’s more, as the genes and proteins involved in the movement of prostate cancer cells are essentially the same as those involved in the movement of other types of cancer cells, pomegranate juice may have a much broader role to play in cancer treatment (www.sciencedaily.com/ releases/2010/12/ 101212121741.htm).
Indeed, previous research has suggested that pomegranate juice can inhibit the growth of breast, colon and lung cancer cells (Nutr Cancer, 2009; 61: 811-5). In test-tube studies using breast cancer cell lines, pomegranate constituents were shown to effectively inhibit angio-genesis (the growth of new blood vessels that enables cancerous tumours to grow and spread) as well as tumour growth, proliferation and invasiveness, and to induce apoptosis (programmed cell death) (Altern Med Rev, 2008; 13: 128-44).
There is also laboratory evidence to suggest that pomegranate juice may help to prevent skin cancer (Exp Dermatol, 2009; 18: 553-61).
However, the most important question is whether pomegranate has proved effective in any clinical trials. So far, only one has involved cancer patients, although the results are promising. Researchers from the University of California at Los Angeles (UCLA) studied 46 men with prostate cancer who drank 8 oz (240 mL) of pomegranate juice every day. They found that prostate-specific antigen (PSA) levels declined significantly over the treatment period, suggesting a potential slowing of cancer progression.
Further research is currently underway to determine whether these early results will be supported by a randomized, double-blind, placebo-controlled trial (Clin Cancer Res, 2006; 12: 4018-26).
Heart disease
In addition to its cancer-fighting activities, pomegranate juice also appears to have cardioprotective properties, making it a useful beverage for those with heart disease. Indeed, a study by a team from The Preventive Medicine Research Institute in Sausalito, CA, found that drinking pomegranate juice had beneficial effects in patients with ischaemic coronary heart disease (CHD). After randomly dividing 45 patients with both CHD and myocardial ischaemia (restricted blood supply to the heart) into two groups, one group was given 240 mL/ day of pomegranate juice for three months, while the other received the same amount of a placebo drink with a similar calorie content, flavour and colour.
The results showed that blood flow to the heart improved by around 17 per cent in the pomegranate group and declined by 18 per cent in the placebo group. The researchers noted that this benefit came with no negative effects on lipids, blood glucose, body weight or blood pressure.
“In conclusion, daily consumption of pomegranate juice may improve stress-induced myocardial ischemia in patients who have CHD,” they wrote (Am J Cardiol, 2005; 96: 810-4).
Another study looked at the effect of pomegranate juice on patients with carotid artery stenosis (CAS), where there is narrowing of the carotid arteries due to the build-up of plaque (atherosclerosis) in vessel walls. This placebo-controlled trial showed that the daily consumption of the fruit juice for one year significantly reduced the thickness of the carotid artery walls by up to 30 per cent. The controls, on the other hand, showed further thicken-ing of the arteries.
Drinking pomegranate juice also appeared to reduce systolic blood pressure and to retard cholesterol oxidation. These effects could be down to the potent antioxidant properties of the polyphenol compounds found in pomegranate juice, the researchers said (Clin Nutr, 2004; 23: 423-33).
However, more studies are needed to determine whether drinking pomegranate juice is a useful strategy for the prevention of heart disease in healthy people.
Diabetes
Despite being naturally high in sugar, pomegranate juice has shown promise in the treatment of health problems associated with diabetes. One small trial of 10 type 2 diabetics and 10 non-diabetic controls found that a daily dose of the juice did not worsen diabetes factors such as blood sugar levels but, instead, resulted in significant antioxidative effects that might be able to cut the risk of heart disease in such patients (Athero-sclerosis, 2006; 187: 363-71).
Heart disease risk is increased in diabetics, as persistently raised glucose levels intensify the ‘furring’ and hardening of blood vessels seen in atherosclerosis.
“In most juices, sugars are present in free-and harmful-forms,” explained lead study researcher Michael Aviram. “In pomegranate juice, however, the sugars are attached to unique antioxidants, which actually make these sugars protective against atherosclerosis.”
In a follow-up study, drinking pomegranate juice proved to have a number of other beneficial effects that “could lead to retardation of atherosclerosis development in diabetic patients” (J Agric Food Chem, 2008; 56: 8704-13).
Alzheimer’s and more
A study by scientists from Loma Linda University in California suggests that pomegranate juice might help to fight off Alzheimer’s disease. Using mice predisposed to develop Alzheimer’s-like pathology and symptoms, the team examined the effect of drinking pomegranate juice (roughly the equivalent of a human drinking one or two glasses a day) or sugar water on the progression of the disease.
Their findings showed that, after six months, the pomegranate juice-treated mice learned water-maze tasks more quickly and swam faster than the control mice, and also had 50-per-cent fewer beta-amyloid plaques in the hippocampus of their brains. The build-up of such plaques is considered one of the hallmarks of Alzheimer’s disease (Neurobiol Dis, 2006; 24: 506-15).
However, clinical trials are needed to confirm whether or not drinking pomegranate juice will have such similar effects in human Alzheimer’s patients.
Also, other animal research has hinted at the juice’s neuroprotective effects. When pregnant mice were given pomegranate juice, the results suggested that polyphenols in the juice might protect their offspring from neonatal hypoxic-ischaemic (HI) brain injury. In humans, HI brain damage is a major cause of infant illness and death in severely preterm and very low-birth-weight babies.
The study showed that the offspring of pomegranate-treated mice had significantly less brain-tissue loss (a 64-per-cent decrease) compared with controls when subjected to experimentally induced HI brain damage. “These results demonstrate that maternal dietary supplementation with pomegranate juice is neuroprotective for the neonatal brain,” the researchers said (Pediatr Res, 2005; 57: 858-64).
Nevertheless, human
studies are again needed.
Pomegranate promise
Despite all the positive findings so far, it’s still too early to say whether or not pomegranate juice can prevent or treat a particular condition. In fact, in the US, the Federal Trade Commission (FTC) has come down hard on claims made for the potential benefits of the popular fruit juice.
In September 2010, the FTC filed a lawsuit against Pom Wonderful, the brand of pomegranate juice used in most of the scientific studies, charging the company with making false and unsubstantiated claims. The commission said that the company’s advertising claims over-stated the results of studies and ignored the fact that some studies found pomegranate juice to be no more effective than a placebo.
The studies being referred to are one that reported no statistically significant effect of pomegranate juice in men with erectile dysfunction, and one that found no significant effect of the juice on arterial plaque build-up in patients
at moderate risk for coronary heart disease (Int J Impot Res, 2007; 19: 564-7; Am J Cardiol, 2009; 104: 936-42).
However, Pom Wonderful strongly disputes the FTC’s assertions. “We do not make claims that our products act as drugs,” the company said. “What we do, rather, is communicate, through advertising, the promising science relating to pomegranates. Consumers and their health providers have a right to know about this research and its results.”
Joanna Evans
A potent antioxidant
The apparently beneficial effects of pomegranate juice have been largely attributed to its antioxidant activity, which is mainly due to the high concentration of polyphenols in the juice. Pomegranate juice has both a higher total polyphenolic content and greater antioxidant activity than other commonly consumed fruit juices, including orange, apple, pineapple, grapefruit, red grape and cranberry (Int J Food Sci Tech, 2010; 45: 1191-7).
It’s also worthwhile noting that the whole juice appears to be superior to its isolated and purified polyphenols in terms of antioxidant, anticancer and anti-atherosclerotic effects. This suggests that the effects of pomegranate juice are most likely due to a synergistic effect of multiple compounds (J Nutr Biochem, 2005; 16: 360-7).
WDDTY VOL. 21 NO. 11
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