Fasting blood specimens will be taken from the patients with IBS that have inclusion criteria. First, the objectives and method of study will be explained to the patients and informed consent form will be taken from them. They will be divided into 4 groups by an adjusted randomized blocking and the clinical outcomes, quality of life, emotional stress questionnaires will be completed before and after intervention. During 6 weeks, they will receive 2 capsules of soy isoflavones per day, 50000IU vitamin D biweekly in addition to the other placebo form, both of them and placebo of both. At the end, body mass index ( BMI), serum TNF-Alpha, TAC, gene expression of GATA3, ROR gamma, FOXP3 in lymphocytes and gut permeability will be measured. The quantity of polymorphisms of vitamin D and estrogen receptors will be determined.

Inclusion Criteria:

1. age 18-75 yrs
2. patients with Irritable Bowel Syndrome (IBS) according to ROME III criteria
3. BMI 18-25
4. a- no intestinal organic diseases b- no intestinal infection c- no history of chronic gastrointestinal and colorectal diseases d- no intestinal major surgery
5. no regular use of antibiotics, anti-constipation and anti-diarrhea, immune suppressors, metoclopramide, cisapride, diphenoxylate, opium and non-steroidal anti-inflammatory drugs
6. no pregnancy and lactation
7. not athlete or bed rest
8. no history of breast cancer in herself or her family
9. no severe psychosis

Exclusion Criteria:

1. a- use of soy isoflavones or vitamin D one year before the study b- use of soy milk or soy nuts during study
2. diet changes during study
3. use of artificial sweetener 2 days before study
4. no desire to complete the study
5. adverse effect of supplement
6. pregnancy during study