Consuming foods with added oligofructose improves stool frequency: a randomised trial in healthy young adults

Abstract

The impact of oligofructose (OF) intake on stool frequency has not been clearly substantiated, while significant gastrointestinal (GI) symptoms have been reported in some individuals. The aim of the present study was to determine the effects of OF on stool frequency and GI symptoms in healthy adults. In an 8-week, randomised, double-blind, parallel-arm study, ninety-eight participants were provided with 16 g OF in yogurt and snack bars (twenty male and thirty female) or matching control foods (seventeen male and thirty-one female), to incorporate, by replacement, into their usual diets. Participants completed a daily online questionnaire recording stool frequency and rating four symptoms: bloating, flatulence, abdominal cramping and noise, each on a Likert scale from '0' for none (no symptoms) to '6' for very severe, with a maximum symptom intensity score of 24 (sum of severities from all four symptoms). Online 24 h dietary recalls were completed during pre-baseline and weeks 4, 6 and 8 to determine fibre intake. When provided with OF foods, fibre intake increased to 24·3 (sem 0·5) g/d from pre-baseline (12·1 (sem 0·5) g/d; P < 0·001). Stool frequency increased with OF from 1·3 (sem 0·2) to 1·8 (sem 0·2) stools per d in males and 1·0 (sem 0·1) to 1·4 (sem 0·1) stools per d in females during intervention weeks compared with pre-baseline (P < 0·05),but did not change for control participants (males: 1·6 (sem 0·2) to 1·8 (sem 0·2); females: 1·3 (sem 0·1) to 1·4 (sem 0·1)). Flatulence was the most commonly reported symptom. Mean GI symptom intensity score was higher for the OF group (3·2 (sem 0·3)) v. control (1·7 (sem 0·1)) (P < 0·01), with few participants reporting above moderate symptoms. No change in symptom intensity occurred over time. Consuming yogurt and snack bars with 16 g OF improves regularity in young healthy adults. However, GI symptoms, resulting from an increase in oligofructose intake, may not diminish with time.

Keywords: Fibre; Gastrointestinal symptoms; Oligofructose; Stool frequency.

Fig. 1.

Participant flow diagram.

Fig. 2.

Daily fibre intake from all foods (total fibre) or non-study foods (food fibre) by study week in individuals receiving study foods without oligofructose (control) or with oligofructose (intervention). ■, Food fibre (control); , total fibre (control); , food fibre (intervention); , total fibre (intervention). Values are means, with standard errors represented by vertical bars. ^a,b,c,d Mean values with unlike letters were significantly different (P < 0·01).

Fig. 3.

Mean daily stool frequency by week. ●, Females (control); ○, females (oligofructose); ▴, males (control); ▵, males (oligofructose). Values are means, with standard errors represented by vertical bars. Main effects: intervention group (I), P = 0·5026; sex (S), P = 0·0067; week (W), P < 0·0001; I × W, P = 0·0044; I × S × W, P = 0·0170. * Mean value was significantly different from that of females in the same group (P < 0·05). † Mean value was significantly different from that at pre-baseline (week 0) for the same group (P < 0·05). ‡ Mean value was significantly different from that at week 1 for the same group (P < 0·05).

Fig. 4.

Probability of reporting at least one of four gastrointestinal (GI) symptoms (flatulence, bloating, abdominal cramping, or noises) (A) or all four symptoms (B) in 1 d during the pre-baseline (week 0) period and 8 weeks of intervention. Daily data were averaged across each week for each participant. ●, Females (control); ○, females (oligofructose); ▴, males (control); ▵, males (oligofructose). Values are least squares means, with standard errors represented by vertical bars. For (A), main effects: intervention group (I), P = 0·0718; sex (S), P = 0·3409; week (W), P < 0·0001; I × S × W, P < 0·0001. For B, main effects: intervention group (I), P = 0·0846; sex (S), P = 0·9355; week (W), P < 0·0001; I × S × W, P = 0·0032. * Mean value was significantly different from that of the control for the same sex (P < 0·05). † Mean values for all the weeks were significantly different from that for the pre-baseline week (P < 0·05). ‡ Mean values for the study weeks 2, 3, 4, 5, 7 and 8 were significantly different from that for the pre-baseline week (P < 0·05). § Mean values for the study weeks 1, 2, 3 and 7 were significantly different from that for the pre-baseline week (P < 0·05).

Fig. 5.

Gastrointestinal (GI) symptom intensity scores during the pre-baseline (week 0) and 8-week intervention periods in males and females consuming the oligofructose-containing or control foods. The daily GI symptom intensity score represents the sum of symptom intensities (0 = no symptom to 6 = very severe symptoms) for flatulence, bloating, abdominal cramping and stomach noises averaged across each week for each participant. ●, Females (control); ○, females (oligofructose); ▴, males (control); ▵, males (oligofructose). Data were analysed as log-normally distributed. Values are back-transformed least squares means, with standard errors represented by vertical bars. Main effects: intervention group (I), P = 0·0009; sex (S), P = 0·9272; week (W), P < 0·0001; I × S × W, P = 0·0095. * Mean value was significantly different from that of the control for the same sex (P < 0·05). † Mean values for all the weeks were significantly different from that for the pre-baseline week (P < 0·05). ‡ Mean values for the study weeks 2 to 8 were significantly different from that for the pre-baseline week (P < 0·05). § Mean value for study week 7 was significantly different from that for the pre-baseline week (P < 0·05).