ConsumerLab.com reported today that only two-thirds of the saw palmetto supplements it recently evaluated contained ingredients similar to those known to work in clinical studies.
Saw palmetto is a popular herb due to its ability to reduce the frequency and urgency of urination in men with prostate enlargement. More than $33 million worth of saw palmetto supplements were sold in the past 12 months in the US according to market research firms SPINS and ACNielsen.
The ConsumerLab.com testers found two products with only half of the amount of the herb known to work. The agency said that although both claimed to contain other botanical ingredients with potential prostate activity, it is not known if these would compensate for the low levels of saw palmetto.
Two other products indicated on their labels that they were made from saw palmetto extracts with lower amounts of fatty acids and sterols than the standard 85 - 95 per cent, with one claiming only '20 - 25 per cent'. A fifth product was found to contain unusually high levels of sterols and specific fatty acids, suggesting the addition of undeclared oil in the product, said ConsumerLab.
"Consumers need to understand that supplements are often designed by marketers, not clinicians," said Dr Tod Cooperman, president of ConsumerLab.com.
Saw palmetto (Serona repens) is a type of palm tree, whose primary medicinal value lies in the oily compounds found in its berries. Most dietary supplements are composed of an extract from the berries or a berry powder.
Cooperman's team recommends that a saw palmetto product claim a daily dose of either 320mg of berry extract or 1-2 grams of berry powder. "Extracts should be standardized to at least 85 per cent fatty acids and 0.2 per cent sterols, while berry powders should be standardized to a minimum of 8.5 per cent fatty acids and 0.02 per cent sterols," they report.
It is the fatty acids in saw palmetto which are purported to be responsible for testosterone-inhibiting effects within the prostate. However the mechanism of action of the sterols is not well understood, although they are present in other herbs (such as pygeum bark, stinging nettle root, and pumpkin seed extract) used in treating symptoms of prostate enlargement. At least 85 per cent of the weight of clinical quality saw palmetto extract products is expected to be attributable to specific fatty acids and at least 0.2 per cent from specific sterols, with a total daily dose of 320 mg of extract, according to ConsumerLab.
Those that passed the test include NOW Foods Saw Palmetto Standardized Extract With Pumpkin Seed Oil and Zinc, Puritan's Pride Inspired By Nature Natural Whole Herb Saw Palmetto Serenoa repens and Nature's Bounty Spring Valley Standardized Extract Saw Palmetto and Vitamin World's Select Herbals Natural Whole Herb Saw Palmetto.
The review can be found on the ConsumerLab website.