Background: Constipation is a functional gastrointestinal disorder and the use of probiotics is considered as a new solution in prevention and treatment of constipation. The aim of this study is to review the clinical evidence about probiotics effects in the prevention and treatment of constipation.

Materials and Methods: To review the accessible evidence about efficacy of probiotics in the prevention and treatment of constipation, the search of key words such as constipation, probiotic and yoghurt are conducted in databases Pubmed, Medlinplus and Cochran from 1980-2013 and of 49 articles about constipation, 16 yandomized controlled clinical trial articles and 3 pre-test and post-test randomized trials that investigated the effects of probiotics on constipation were included in this study.

Results: Probiotics produced lactic acid and fatty acids with short chains that decrease the colon pH and stimulate muscular contractions and intestinal peristalsis. Some of probiotics can increase the mucous discharge and change linked bile salts to free bile salts entering much water to colon and leads to soft defecation.

Conclusion: Considering studies, daily use of probiotics such as lactobacillus acidophilus and bifidobacteria lactic 10⁵-10¹¹ CFU/gr for at least 1-2 weeks can help to decrease constipation.