- A recent review finds no solid evidence for the numerous claims made by the health supplement Pycnogenol.
- Of the 15 randomized controlled trials of Pycnogenol, the manufacturer sponsored 11, making them likely to be biased.
The manufacturer of a dietary supplement made from French pine bark, Pycnogenol®, markets it widely for the prevention or treatment of many chronic disorders, ranging from asthma to erectile dysfunction, but a recent systematic review found no sound basis for the claims.
“We found that no solid evidence exists to support health claims that are being made for the antioxidant supplement Pycnogenol®,” said senior author Jimmy Volmink, M.D., Ph.D., Dean of the Faculty of Health Sciences at Stellenbosch University in South Africa and director of the SA Cochrane Centre, Medical Research Council of South Africa. “Only 15 randomized controlled trials…have evaluated the effects of Pycnogenol®.” The manufacturer sponsored 11 of them.
Pycnogenol® is derived from the bark of pine trees that grow only in southern France. It contains the antioxidant proanthocyanidin, which is present in fruits, red wine and chocolate.
Dietary supplements represent a multibillion industry, notes Volmink. “Steps are currently being taken in several countries to improve the regulation of the dietary supplement industry, in terms of quality, safety and the validity of health claims.” Meanwhile, consumers must interpret claims cautiously, he said.
The fifteen trials - performed in the USA, Europe, China and Iran - involved 791 participants. The disorders studied included asthma, attention deficit hyperactivity disorder, chronic venous insufficiency, diabetes, erectile dysfunction, hypertension and osteoarthritis. Two trials were done with children; the rest with adults.
The new review's authors could draw no solid conclusions regarding benefits that many studies purported to find. The 15 trials exhibited poor quality, with small sample sizes (11 to 156 participants) and often inadequate blinding. Key results were sometimes missing for relevant outcomes and some trials provided results only for the treatment group taking Pycnogenol®, but not for controls.
Roberta W. Scherer, Ph.D., an associate scientist at the Johns Hopkins Bloomberg School of Public Health said, “A majority of the studies were funded by the manufacturer, leading to increased risk of bias.” She noted that because the trials had small samples, it is difficult to have confidence in the findings. The trials also examined diverse outcomes, making combining the results difficult or impossible. “Also, safety is hard to assess with small trials,” she said. “It’s not really shown” in small, short-term trials like those done on Pycnogenol®.
Both scientists called for bigger, better studies of Pycnogenol® before consumers can trust in its efficacy and safety.
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The Cochrane Library (http://www.thecochranelibrary.com) contains high quality health care information, including systematic reviews from The Cochrane Collaboration. These reviews bring together research on the effects of health care and are considered the gold standard for determining the relative effectiveness of different interventions.
Schoonees A., Visser J., Musekiwa A., Volmink J. (2012). Pycnogenol® for the treatment of chronic disorders. The Cochrane Library, Issue 2.