Constipation is a prevalent intestinal disorder. Lactobacillus casei strain Shirota (LcS) shows potential effect on alleviating constipation. This study evaluated the impact of fermented milk containing LcS on stool consistency and frequency. The stool short chain fatty acid and gut microbiota were also assessed.

Inclusion Criteria:

• meet ROME Ⅲ criteria for functional constipation
• normal body mass index between 18.5 and 29.9

Exclusion Criteria:

• had a serious disease;
• used systemic antibiotics or antimycotics medication and antidiarrheal or laxative medication in the 30 days prior to the study;
• allergic to milk protein;
• constipated because of organic or neurological lesions;
• participated in any other studies within 2 months prior to this study.