Table grapes are high in flavonoids, which are thought to have strong antioxidant and anti-inflammatory properties. Now, researchers at the Johns Hopkins University School of Medicine, Baltimore, have shown that powdered grapes appear to reduce pain and inflammation in a rat model of arthritis, where rats knees are inflamed using a chemical injection.

Some rats were fed the powdered equivalent of 10 cups of grapes once a day after the arthritis-inducing injection, while others got only sugar water. Over the course of 4 days after the chemical injection, the researchers tested the rats’ inflammation levels and pain responses by measuring their sensitivity to mechanical stimulation such as prodding their paws and measuring the amount of knee swelling. Rats fed grape powder could withstand stronger prodding than their sugar-fed counterparts.

The researchers also compared the grape powder treatment with a common nonsteroidal anti-inflammatory drug, meloxicam, and found that while the dose of meloxicam alone was not sufficient to reduce pain, animals fed a combination of grape powder and meloxicam experienced even less pain from their arthritis than animals that received either substance alone. The combination treatment also reduced the knee swelling associated with inflammation.

"I think there are two important messages here," says Jasenka Borzan, PhD, a research associate in anesthesiology at Hopkins. "That consuming flavonoids through natural products like grapes can be beneficial to health in general and also specifically for reducing inflammatory pain; and that consuming natural products like grapes may also be beneficial in reducing the amount of medication necessary to reduce inflammation."