Pine bark extract (oligopin) is a rich source of polyphenols that exerts strong antioxidant and anti-inflammatory activities. It has also beneficial effects on bone turnover based on in vitro studies and animal models. Investigators aimed to investigate the effects of oligopin on bone turnover markers and plasma and peripheral mononuclear cells oxidative stress in postmenopausal women with osteopenia in a double-blind randomized clinical trial. Participants are forty four women with osteopenia divided into two groups randomly (22, having oligopin, 150 mg, once daily, for 12 weeks). The 2nd group (22 women with osteopenia) receives the same amount of the placebo. At the first and the end of the study, blood sample are taken to measure in order to peripheral blood mononuclear cells isolation and plasma separation. The levels of bone alkaline phosphatase and carboxy terminal collagen type I in plasma oxidative stress markers such as total anti-oxidant capacity, malondialdehyde, and protein carbonyl were evaluated. Furthermore, oxidative stress will be evaluated in peripheral blood mononuclear cells by measurement of expression and activity of magnesium superoxide dismutase,catalase and Nuclear factor (erythroid-derived 2)-like 2.