Monaz: Hello, I'm Monaz Mehta, editor in the Cochrane Editorial and Methods department. Pine bark extract supplements are marketed to prevent or treat a wide range of chronic diseases and a Cochrane Review from September 2020 assesses the evidence on their efficacy and safety. Monika Evans spoke with lead author, Nina Robertson from Stellenbosch University in South Africa about the findings.

Monika: Hello Nina, perhaps you could begin by telling us a little about what's in pine bark extract and why you did the review.

Nina: Thanks Monika. The main ingredient of pine bark extract is a powerful antioxidant called proanthocyanidin, which is also found in some fruits and nuts, red wine, tea and chocolate. It's sold in a range of dietary supplements but the source and quantity of proanthocyanidin in these vary, as do the other ingredients they contain. The manufacturers of the supplements strongly promote research and make claims that their products are based on the results of scientific research and we hope that bringing the relevant research together will help consumers to make an informed decision about whether or not to use pine bark extract supplements.

Monika: Before we get to the results, tell us a bit more about what you wanted to include in the review.

Nina: We searched for randomized trials that had tested pine bark extract supplements in adults or children, with any chronic disorder. We wanted to cover diseases such as heart disease, stroke or cancer; and non-specific illnesses like fatigue or pain. We used primary outcomes based on the patient's disorder and grouped these into participant-reported outcomes (such as joint pain for osteoarthritis) and investigator-reported outcomes (such as cholesterol levels). We also looked for data on death from any cause, and information on serious and non-serious adverse effects.

Monika: That sounds quite wide ranging, how much material did you find?

Nina: We identified 27 eligible trials, with a total of 1641 participants, that had evaluated pine bark extract supplements for 10 different chronic disorders, including attention deficit hyperactivity disorder (or ADHD), asthma, cardiovascular disease and its risk factors, chronic venous insufficiency, diabetes, erectile dysfunction, female sexual dysfunction, osteopenia, osteoarthritis and traumatic brain injury. However, few of these studies provided the information we needed.

Monika: That's a shame. What do the studies show?

Nina: The findings were mixed, and although some of the studies did point towards possible benefits from pine bark extract, we need to be cautious for several reasons. For example, the small number of people with each condition means that the findings may simply be due to the play of chance, and, although we'd have liked to overcome this to some extent by pooling the results in meta-analyses, we couldn't do so because of variations across studies, in things such as the outcomes they chose and how they measured them. There were also problems in study design and reporting that might have led to bias, and we can't be sure that other studies of similar sizes but with less positive results might be completely unpublished and not available to us.

Monika: With those problems in mind, what's the take home message from the review?

Nina: The main conclusion is that the currently available evidence is not sufficient to support claims regarding the benefits of pine bark extract supplements, or to reassure people about their safety in the chronic conditions we came across. Users or potential users need to know this and healthcare professionals need to be aware of the diverse range of chronic conditions for which pine bark extract supplements are promoted, and the lack of evidence for their efficacy and safety. This would better equip them to guide individuals trying to decide whether to take a pine bark extract supplement for their condition.

Monika: Thanks Nina. Those are important conclusions and if someone would like to find out more, how they can get hold of the review?

Nina: It's published online at Cochrane Library dot com and is easy to find there with a simple search for 'pine bark'.