NIH Logo Saw palmetto is an herbal dietary supplement that is primarily used for the treatment of prostate enlargement. A study by the National Institutes of Health, has unfolded that saw palmetto is apparently not useful in treating urinary problems related to prostate enlargement as compared to placebo.

This double-blind randomized placebo-controlled clinical trial was conducted in America at 11 places from June 2008 to October 2010. Around 369 men aged 45 or more with less than normal peak urine flow rate enrolled for the study. They also had an American Urological Association Symptom Index (AUASI) score in the range 8 and 24 where a lower score is considered better. Increasing doses of saw palmetto or placebo were administered to the men starting with one progressing to 2 and finally 3 tablets of 320 milligrams a day which was elevated at 24 and 48 weeks.

“Investigators designed the current trial to determine whether daily doses of up to 960 milligrams — three times the standard daily dose — would prove better than a placebo at improving lower urinary tract symptoms in men due to BPH. We were disappointed to find that higher doses of saw palmetto did not improve symptoms more than placebo,” commented Robert A. Star, M.D., director of the NIDDK’s Division of Kidney, Urologic and Hematologic Diseases.

The investigators compared the initial AUASI score to the one attained at the end of 72 weeks. Other variables like improvement in frequency, nighttime urination, peak urine flow, prostate specific antigen level, sexual function, incontinence and sleep quality were also calculated.

The outcomes showed that the mean AUASI scores seemingly lowered from 14.4 to 12.2 points for saw palmetto extract while it reduced from 14.7 to 11.7 points if placebo was used. This difference of 0.79 points seemed to be in favor of placebo. Also, saw palmetto did not appear to be more effective for any of the secondary results as compared to placebo.

The study is published in the Journal of the American Medical Association.