(1)Objectives: The effects of conjugated fatty acids (C.F.A) supplement on metabolic parameters in patients with benign breast tumor in concerning with the polymorphism of PPARγ gene. (2)Key inclusion criteria: Pathology report or sonography confirmation for benign breast tumors; Tendency to participate in study; 25-47 years old; Body mass index (B.M.I) less than the ratio of 35 kilogram to squared meter. (3)Key exclusion criteria: Being in lactation and pregnancy conditions; Being menopause; Taking insulin or oral anti-diabetic drug in each phase of the study by patients; Malignant diseases or any history of malignancy; Thyroid disorders; Acute liver failure; Getting hormonal disorders before benign breast disease (B.B.D) diagnosis (such as poly cystic ovary syndrome, type 1 diabetes, hypoglycemia, and adrenal gland disorders); Any sever gastrointestinal disease; History of chemotherapy, radiotherapy, and hormone therapy; Taking glucocorticoid, anticoagulant, antiepileptic, contraceptive drugs, and hormone replacement therapy (H.R.T); Taking fish liver oil supplement more than 2,000 mg per day; Being heavy smoker in the past year before the diagnosis of B.B.D; Vigorous physical activity. (4)Participants and sample size: This study will be conducted on 50 women with B.B.D who meet inclusion criteria. Patients will be randomly divided into a treatment group of 25 cases and placebo of 25 cases based on type of disease. (5)Interventions: In a parallel manner, treatment group will receive 1000 mg per day CFA-containing oil (one 1000 mg soft-gel capsule) with 10 IU vitamin E and placebos will consume 1000 mg per day combined inert oil (one 1000 mg soft-gel capsule containing 350 mg sunflower oil, 350 mg palm olein, 300 mg corn oil) with 10 I.U vitamin E for 13 weeks. Placebo capsules will be virtually similar to C.F.A capsules. (6)Primary outcomes: measurement of metabolic parameters including insulin, glucose, peptide C, PPARγ, IGFBP-3, and IGF-1 at baseline and endpoint of intervention.