In the present study the effect of whole fruit and medolla powder of Elaeagnus angustifolia supplementation in comparison with placebo (corn starch+Isomaltose) on clinical manifestation, inflammatory factors, matrix metalloproteinase enzymes, oxidative stress and nutritional status of patients with knee osteoarthritis will be evaluated. To achieve this objective, 90 volunteer female patients with bilateral primary osteoarthritis of knee who are refereed to university clinic, will be randomly divided into three groups (including 2 intervention groups and one control group). The patients in the first intervention group will receive 15 grams of whole fruit powder of Elaeagnus angustifolia and the patients in the second intervention group will receive 15 grams of medolla powder of Elaeagnus angustifolia and patients in placebo group will receive corn starch and Isomaltose for 8 weeks. WOAMC (Western Ontario and McMaster Osteoarthritis questionnaire) will be used for evaluation the clinical manifestations (pain, joint stiffness and disability) of the patients. Before and after intervention, beside the anthropometric and dietary intake assessments, 5 cc of fasting blood will be drawn for determining total antioxidant and Malondialdehyde (MDA), Interleukin-1(IL-1), Interleukin-10 (IL_10), Tumor necrosis factor-alpha (TNF-alpha), Matrix metalloproteinase-1(MMP-1) and Matrix metalloproteinase-13 (MMP-13).