Pilot Study: Effectiveness of Different Kefir Formulations on Symptoms of Functional Constipation in Chilean Adults. (KEF-CON)

Participants receive homemade kefir prepared with whole milk (6% grain inoculation, 48-hour fermentation), with an escalating daily dose of 50, 100, 150 and 200 mL. In addition to dietary counseling

Homemade kefir produced by fermenting whole milk with kefir grains (6% inoculation, 48-hour fermentation). Administered orally once daily for 1 month. The dose is escalated every 24 hours during the first 3 days (50 mL on day 1, 100 mL on day 2, 150 mL on day 3), reaching 200 mL/day from day 4, which is maintained until the end of the intervention. Differs from the skim milk formulation in fat content. In addition a dietary couselling

Single standardized nutritional counseling session for chronic functional constipation, delivered by a registered dietitian at baseline after randomization, including recommendations on dietary fiber, fluid intake and eating habits. Participants are followed for 1 month.

Participants receive homemade kefir prepared with skim milk (6% grain inoculation, 48-hour fermentation), with an escalating daily dose of 50, 100, 150 and 200 mL. In addition to dietary counseling

Single standardized nutritional counseling session for chronic functional constipation, delivered by a registered dietitian at baseline after randomization, including recommendations on dietary fiber, fluid intake and eating habits. Participants are followed for 1 month.

Participants receive homemade skim milk kefir orally once daily for 1 month, with a dose escalated every 24 hours during the first 3 days (50, 100 and 150 mL) and maintained at 200 mL/day from day 4 until the end of the intervention.In addition a dietary couselling

Participants receive standardized dietary counseling for chronic functional constipation, without kefir supplementation.

Single standardized nutritional counseling session for chronic functional constipation, delivered by a registered dietitian at baseline after randomization, including recommendations on dietary fiber, fluid intake and eating habits. Participants are followed for 1 month.

Functional constipation symptoms were assessed with the Rome IV diagnostic criteria. Each participant was scored on six criteria: straining, lumpy or hard stools (Bristol Stool Form Scale types 1-2), sensation of incomplete evacuation, sensation of anorectal obstruction or blockage, and manual maneuvers to facilitate defecation, each present in more than 25% of defecations, plus fewer than 3 spontaneous bowel movements per week. The score ranges from 0 (minimum, no criteria met) to 6 (maximum, all criteria met). Higher scores indicate more severe constipation, which is a worse outcome. At baseline, criteria were assessed according to the Rome IV time requirement (symptoms present during the last 3 months, with onset at least 6 months before diagnosis). At the end of the intervention, they were assessed for the 1-month intervention period. The change from baseline (number of criteria at the end of the intervention minus baseline) was compared between the homemade whole-milk kefir group

Constipation-specific quality of life was assessed with the Patient Assessment of Constipation Quality of Life questionnaire (PAC-QOL). It is a self-administered instrument of 28 items grouped into four subscales: physical discomfort (4 items), psychosocial discomfort (8 items), worries and concerns (11 items) and satisfaction (5 items). Each item is rated on a 5-point Likert scale from 0 to 4. The satisfaction items are reverse-scored. The overall score is the mean of all items, and each subscale score is the mean of its items. Overall and subscale scores range from 0 (minimum) to 4 (maximum). Higher scores indicate worse quality of life. The change from baseline (overall score at the end of the intervention minus baseline) was compared between the homemade whole-milk kefir group, the homemade skim-milk kefir group and the standard dietary counseling group. A negative change indicates improvement in quality of life.

Participants recorded each bowel movement in a self-report diary. Weekly bowel movement frequency was calculated as the number of bowel movements per week. The change from baseline (weekly frequency at the end of the intervention minus baseline) was compared in two ways: first, between each homemade kefir group (whole milk and skim milk) and the standard dietary counseling group; second, between the homemade whole-milk kefir group and the homemade skim-milk kefir group. A positive change indicates an increase in bowel movement frequency, which is a better outcome.

Participants recorded each bowel movement in a self-report diary. For the end-of-intervention value, the mean number of bowel movements per week was calculated from all diary records over the entire 1-month intervention period. The change from baseline (mean weekly frequency over the intervention period minus baseline frequency) was compared in two ways: first, between each homemade kefir group (whole milk and skim milk) and the standard dietary counseling group; second, between the homemade whole-milk kefir group and the homemade skim-milk kefir group. A positive change indicates an increase in bowel movement frequency, which is a better outcome.

Unit of Measure:

bowel movements per week

Health-related quality of life was assessed with the EuroQol 5-Dimension, 3-Level questionnaire (EQ-5D-3L), which has two components. The descriptive system covers five dimensions (mobility, self-care, usual activities, pain/discomfort and anxiety/depression), each rated at three levels (no problems, some problems, extreme problems). Responses were converted into a single index score using the Chilean time trade-off value set (Zarate et al., 2011). The index ranges from [value of minimum; values below 0 represent health states considered worse to 1 maximum; full health. The visual analogue scale (EQ VAS) records self-rated health on the day of assessment, from 0 (minimum; worst imaginable health) to 100 (maximum; best imaginable health). For both components, higher scores indicate better health status. The change from baseline (score at the end of the intervention minus baseline) was compared for each component in two ways: first, between each homemade kefir

Sensory acceptability of the homemade kefir was assessed at the end of the intervention with a 7-point hedonic scale (Likert type) in participants allocated to the whole-milk or skim-milk kefir groups. Participants rated each sensory attribute (appearance, color, aroma, flavor, texture and overall acceptability) from 1 (minimum; dislike very much) to 7 (maximum; like very much), with 4 representing neither like nor dislike. Each attribute was scored separately. Higher scores indicate greater acceptability, which is a better outcome. The scores for each attribute were compared between the homemade whole-milk kefir group and the homemade skim-milk kefir group. Participants in the standard dietary counseling group did not consume kefir and were not assessed.

Unit of Measure:

score on a scale

Adherence was assessed in participants allocated to the whole-milk or skim-milk kefir groups using a self-report log. Each day, participants recorded whether the prescribed daily dose was consumed or not consumed. The prescribed dose escalated over the first three days (50 mL on day 1, 100 mL on day 2 and 150 mL on day 3) and was then 200 mL/day from day 4 until the end of the intervention. Adherence was calculated as the number of daily doses consumed divided by the total number of prescribed daily doses, multiplied by 100. Scores range from 0% (minimum) to 100% (maximum). Higher percentages indicate greater adherence, which is a better outcome. Adequate adherence was defined as consuming at least 80% of the prescribed daily doses. Adherence was compared between the homemade whole-milk kefir group and the homemade skim-milk kefir group. Participants in the standard dietary counseling group did not consume kefir and were not assessed.

Unit percentage of prescribed daily doses

Adverse events were recorded weekly throughout the intervention in participants allocated to the whole-milk or skim-milk kefir groups. Gastrointestinal adverse events included bloating, flatulence, abdominal pain or cramping, nausea and diarrhea. Any other adverse event reported by participants was also recorded. Each event was classified by severity (mild, moderate or severe) and by its relationship to kefir consumption (related or not related). The number and percentage of participants with at least one adverse event, overall, by type of event, by severity and by relationship to kefir, were compared between the homemade whole-milk kefir group and the homemade skim-milk kefir group. Adverse events were not recorded in the standard dietary counseling group, because its participants did not receive kefir.

Unit of Measure:

participants