Complaints of constipation increase with age due to changes in the intestinal flora 1), tendency of intestinal contents’ stagnation because of intestinal tract inactivity, and decreased dietary fiber and other nutrient intake for gut bacteria because of decreased masticatory function. Diet that improves constipation includes probiotics, prebiotics, and combination of both (i.e., synbiotics).
In Japan, older adult facilities providing long-term care are broadly classified as acute care hospitals and homes (rehabilitation wards and nursing homes).
This study aimed to determine whether constipation symptoms are ameliorated by supplementation of a regular diet with synbiotics for older adults, requiring long-term care, who reside in these facilities and have constipation symptoms.

This study had a quasi-experimental design (single-group time-series). The intervention period for each case was 6 weeks (stage 1, 1 week of pre-observation; stage 2, 3 weeks of synbiotics intake; and stage 3, 2 weeks of follow-up). The study subjects were institutionalized older adults aged ≥65 years requiring long-term care with a Constipation Assessment Scale (CAS) score of ≥5 points. The facilities were two rehabilitation wards and one nursing home.
Patients’ regular diet was supplemented with two kinds of beverage containing lactic acid bacteria as a synbiotics for 3 weeks: Yakult Ace® (2.5 g of galacto-oligosaccharide and ≥30 billion L. casei YIT 9029 strains) and Yakult Milmil S® (3.1 g of dietary fiber, 1.0 g of galacto-oligosaccharide, and ≥12 billion BY strains).
A daily stool/meal journal for 6 weeks was maintained, and the CAS score was measured each weekend. The Barthel Index was assessed at the end of each stage. The primary end-point was the CAS score compared before and 3 weeks after diet intake. The secondary end-points were the CAS score, stool frequency, stool characteristics, stool volume, and number of persons using laxative compared before intake and each week thereafter. The Wilcoxon and Friedman tests were used for statistical analysis (significance level: 0.05).
In addition, the standards for laxative use were defined, and a nurse assessed the abdomen and rectum based on stool characteristics and daily stool frequency, determined the use of laxatives and defecation methods, and confirmed the changes.

During the intervention period (August 2017 to April 2018), 36 patients were recruited and 29 completed the study protocol. Their mean age was 88.9 (standard deviation [SD], 6.6) years, and their mean body mass index was 20.8 (SD 3.3) kg/m2 in males and 20.1 (SD 3.5) kg/m2 in females. A significant difference was observed in the primary end-point of the CAS score before (6.3 [SD 1.3] points) and 3 weeks after synbiotics intake (3.4 [SD 2.0] points) (p < .001), with improvement in all symptoms. In the secondary end-point, the CAS score measured before and after each week of synbiotics intake was compared, and significant differences were noted for all weeks, including during the follow-up observation period (p < .001) (Table 1). The highest degree of improvement was noted in the second week of intake.
Compared with before intake, seven items (abdominal bloating, stool frequency, distension, anal pain, stool volume, evacuation status, and diarrhea) reached a subjective symptom score of ≤50% once after synbiotics intake and one item (evacuation of gas) reached ≤60% after intake　(Table 2). Stool journals revealed no significant differences in stool frequency, characteristics, or volume. Laxatives were used by 24 patients but 5 stopped during the first week of intake, which increased to 17 on the sixth week. The 3 people who had fecal incontinence during pre-observation fully recovered and could use the toilet for defecation.
Based on the diet journal, daily dietary fiber intake was 10.9–12.1 g, which was at least 5 g lower than the amount recommended in Japan (19 g for males and 18 g for females).

The Japanese diet is rich in probiotics and prebiotics, resulting in the natural consumption of synbiotics. However, older adults requiring long-term care currently residing in older adult care facilities have a chronic lack of dietary fiber, causing dysbiosis. This study revealed that consumption of synbiotics ameliorated constipation symptoms.
No significant differences in stool frequency, volume, or characteristics were likely noted before and after intake because of mild constipation symptoms; therefore, numerous patients showed normal stool characteristics, and the amount of dietary fiber was insufficient to cause changes in stool volume.

The results suggest that taking synbiotics for 3 weeks ameliorates mild constipation symptoms in institutionalized older adults requiring long-term care and that fecal incontinence improves by terminating the use of laxatives. It was also suggested that institutionalized older adults requiring long-term care have chronic dietary fiber deficiency. Therefore, the effect of synbiotics intake on severe constipation symptoms should be examined in the future.

Mituoka T. 19929 Intestinal flora and aging. Nutr Rev 50:438-446