Pomegranate extract shows joint health potential

The onset and severity of arthritis was delayed and reduced in mice models, according to findings published online ahead of print in the journal Nutrition .

The study adds to the joint health science of the fruit, with previous reports indicating pomegranate extracts may block enzymes that contribute to cartilage degradation in osteoarthritis.

"The results of these translational studies and studies reported previously together provide strong and compelling evidence to support further clinical testing of pomegranate extract for the prevention of rheumatoid arthritis and osteoarthritis," wrote lead author Meenakshi Shukla from Case Western Reserve University and the University Hospitals of Cleveland.

Pomegranate, a rich source of antioxidants, has been linked to improved heart health, but a growing body of science indicates the fruit protect against prostate cancer and slowing cartilage loss in arthritis.

It is these antioxidants, and particularly ellagitannin compounds like punicalagins and punicalins, which accounts for about half of the fruit's antioxidant ability, that are reportedly behind the proposed health benefits.

Delaying the onset and cutting the severity of arthritis Using collagen-induced arthritis (CIA) in mice, a widely used animal model of rheumatoid arthritis, Shukla and co-workers evaluated the potential of a polyphenol-rich pomegranate extract (POMx) as a powder to reduce markers of inflammation and measure overall joint health.

Twenty-four animals were divided into three equal groups and assigned to receive a standard diet with water (control), water plus 13.6 mg per kg of POMx, or water plus 34 mg per kg of POMx for ten days prior to the induction of the arthritis using collagen.

The severity of arthritis was significantly decreased in the animals receiving POMx, with a reduction of 69.2 and 76 per cent in the groups consuming 13.6 and 34 mg per kg of POMx, respectively.

Moreover, POMx was associated with a decrease in the incidence of arthritis, with all the animals in the control group developing the condition, but only 70 and 60 per cent of animals in the 13.6 and 34 mg per kg of POMx groups, respectively.

The average number of days for arthritis to develop after the collagen treatment was delayed in both groups receiving pomegranate with their drinking water, increasing from about 34 days in the control group to 46 and 43.5 days in the 13.6 and 34 mg per kg of POMx groups, respectively.

Furthermore, damage to the joints, measured by levels of nitric oxide in the joints, was reduced. "

Because high-level expression of NO affects the cellular response to injury and its high levels can be pathogenic, these results suggest that POMx may inhibit joint damage by suppressing the production of NO," wrote the researchers.

Biomarkers of inflammation Inclusion of pomegranate extracts in the drinking water of the animals had beneficial effects on the levels of inflammatory cytokines.

Shukla and co-workers report that levels of the bone-destructive molecule interleukin-6 (IL-6) were significantly reduced in POmx-fed animals, compared to control.

Moreover, levels of of IL-1beta, an immune system protein reported to play an important role in causing joint destruction in people with rheumatoid arthritis, were also reduced in the pomegranate-fed animals, but the reduction was not statistically significant, added the researchers.

"Our studies suggest that inhibition of a spectrum of signal transduction pathways and the downstream pathogenic cellular response by POMx or compounds derived from it may be a useful approach for the prevention of the onset and severity of inflammatory arthritis," they wrote.

Approximately seven million people in the UK alone are reported to have long-term health problems associated with arthritis.

Around 206 million working days were lost in the UK in 1999-2000, equal to £18bn (€26bn) of lost productivity.

Safety issues "We must mention that, to our knowledge, no clinical trials in patients with RA have yet been done to document the safety and efficacy of POMx or other extracts of pomegranate available for over-the-counter use."

While no studies have reported safety in relation to arthritis, scientists from the University of California, Los Angeles (UCLA) reported last year that an ellagitannin-rich pomegranate extract is safe and effective in enhancing the antioxidant profile in humans.

Two studies, both in overweight subjects, confirmed the safety of the ellagitannin-rich pomegranate extract, with no adverse effects reports, and showed a significant reduction in thiobarbituric acid reactive substances (TBARS) in the blood linked with cardiovascular disease risk.

The findings were published in the Journal of Agricultural and Food Chemistry (November 2007, Vol. 55, pp.10050-10054).

Source: Nutrition (Elsevier) Published online ahead of print 19 May 2008, doi: 10.1016/j.nut.2008.03.013 "Consumption of hydrolyzable tannins-rich pomegranate extract suppresses inflammation and joint damage in rheumatoid arthritis" Authors: M. Shukla, K. Gupta, Z. Rasheed, K.A. Khan, T.M. Haqqi