Pine bark (Pycnogenol)

Origin: An extract from the bark of the French maritime pine tree

What we know: Pycnogenol contains procyandin, a powerful antioxidant, and also seems to inhibit pro-inflammatory enzymes, including COX 1 and COX 2.

Studies: Among the research: A small 2007 University of Arizona study found pycnogenol reduced osteoarthritis pain by 43 percent and stiffness by 25 percent. Two 2008 studies showed significant improvements in joint pain, stiffness and function that persisted after the supplement was stopped. But a 2012 review concluded that these studies were poorly designed and underpowered.

Dosage: Capsules, tablets: In studies, 100 to 150 mg daily.