Raspberry extracts show joint health potential: Rat study

A polyphenol-enriched raspberry extract was associated with a decrease in the rate of cartilage degradation in a cell study, while data from rats indicated a lower incidence and severity of arthritis, according to findings published in the Journal of Agricultural and Food Chemistry​.

“This study provides insights into the anti-inflammatory effects of the red raspberry fruit and adds to the growing body of biological data on polyphenolic-enriched berry extracts,”​ wrote researchers led by Navindra Seeram, PhD.

“However, whether regular consumption of red raspberry fruit may have beneficial effects on joint health will require future human clinical studies.”​

The study was funded by the Washington Red Raspberry Commission.

Arthritis​

According to the Centers for Disease Control and Prevention (CDC), arthritis is the leading cause of disability in the US, affecting some 21 million adults.

This number is predicted to rise to 67 million adults aged over 18 by the year 2030, according to data from the 2003 National Health Interview Survey (NHIS).

There are numerous nutritional supplements offering joint health support. The market for such products is dominated by glucosamine. Euromonitor International puts the value of the global market for glucosamine supplements at $2bn, and cites an annual growth rate of 7% from 2004 to 2009.

And glucosamine is not alone, and formulations often also contain chondroitin sulfate. The scientific literature also contains other ingredients with potential joint health benefits, including extracts from French maritime pine bark (Pycnogenol), eggshell membranes (ESM Technologies), seaweed (Marigot and Marinova), and collagen (InterHealth and BioCell).

Raspberry​

The new study, if reproducible in additional studies and human studies in particular, could also see red raspberry extracts added to the list of potential natural products for joint health.

The Rhode Island scientists performed in vitro and in vivo studies with a polyphenolic-enriched red raspberry extract containing 20% total polyphenols, 5% anthocyanins, and 9.25% ellagitannins.

The cell study revealed that the raspberry extract decreased the rate of degradation of proteoglycan and type II collagen – both key components of joint cartilage.

Using lab rats, Dr Seeram and his co-workers investigated the effects of the raspberry extract on the development of arthritis following an injection to induce the joint disease.

Results from these tests showed that doses of 120 mg/kg were associated with a “lower incidence and severity of arthritis compared to control animals”​.

Commenting on the potential mechanism, the scientists proposed that the polyphenols in the extract exert anti-inflammatory effects. However, no tissue or blood samples were collected from the animals, and the “mechanism underlying these observed effects needs further investigation”,​ they said.

“Also, it is noteworthy that after ingestion, polyphenols are known to be poorly bioavailable and extensively metabolized. Thus, the colonic catabolism of red raspberry polyphenols and the formation of further bioactive metabolites could contribute toward the health benefits observed for this fruit.​

“Therefore, although it is likely that the effects seen here are resulting from red raspberry extract polyphenol-derived metabolites, further studies would be required to investigate this,”​ they added.

Source: Journal of Agricultural and Food Chemistry​
Published online ahead of print, doi: 10.1021/jf203456w
“Anti-inflammatory Effects of Polyphenolic-Enriched Red Raspberry Extract in an Antigen-Induced Arthritis Rat Model”​​
Authors: D. Jean-Gilles, L. Li, H. Ma, T. Yuan, C.O. Chichester, N.P. Seeram