Dietary Soy May Reduce Pain and Inflammation 34055

Dietary Soy May Reduce Pain and Inflammation

BALTIMORE--A soy-based diet may be able to reduce pain and inflammation related to connective tissue damage, according to scientists from Johns Hopkins University, who presented a study at the annual meeting of the American Pain Society (www.ampainsoc.org), March 14 to 17. Researchers compared a soy protein diet with a casein protein diet in rats to determine if the soy diet would reduce the pain and inflammation of edema--an abnormal accumulation of serum fluid in connective tissue.

Rats were divided into groups of 10 and received either a soy protein diet or a casein protein diet, which were administered two weeks prior to and throughout the study period. Researchers induced edema in the rats' back hind paws by injecting either saline or complete Freund's adjuvant (CFA)--an emulsion of aqueous antigen in oil that contains inactivated Mycobacterium tuberculosis--to cause inflammation. The researchers measured the rats' paws and tested them for pain thresholds to pressure and heat at baseline and then at six, 24, 48 and 96 hours post-injection.

Test results indicated that diet did not affect paw thickness or pain threshold to heat or pressure prior to injection. By six hours post-CFA injection, all rats displayed a low tolerance to both heat and pressure stimuli as compared to baseline values. The rats on the soy diet demonstrated significantly smaller paw measurements than the rats on the casein diet, and they also demonstrated a significantly greater tolerance to heat stimuli. However, researchers did not note a difference between the diet groups in terms of tolerance to pressure tests. Researchers concluded that a soy diet may have application in reducing edema and heat sensitivity but not pressure sensitivity.