Data are presented on participants from the two randomized cross-over trials (Pinto/BEP and BB) and one 2 × 2 factorial parallel arm trial (PintoPA). There were no statistically significant differences between the study-group characteristics (Table ). Almost all of the participants in the three trials self-identified as white with a mean age of 42 years, and an average BMI of 28.3 kg/m2 (Table ).
Baseline demographic characteristics of study participants in an investigation of perceptions of flatulence from beans
Studies Pinto/BEP and BB - cross-over trials
In the first week of each bean intervention of the randomized cross-over trials, reports of increased flatulence varied by bean type (Table ). The fewest accounts of increased flatulence occurred with the black-eyed peas (19%). About the same number of people had increased flatulence with the pinto (50%) and vegetarian baked beans (47%). Only one person had increased flatulence with the carrot control treatment in week 1. By the second week of the cross-over trials, reports of increased flatulence dropped to 6% of participants for the pinto beans, 12% for the black-eyed peas and to 24% for the vegetarian baked beans. Reports of increased flatulence continued to decline over weeks 3-8, with only one to two participants reporting these symptoms with the pinto beans or the black-eyed peas. For the cohort in Study BB, the percentage of persons reporting increased flatulence stayed at 29% in week 3, but dropped to 11% in week 4. Two to three or 7-11% of participants continued to report increased flatulence with the baked beans during weeks 4-8. One to four participants reported increased flatulence while consuming the canned carrots during the control phases of both the Pinto/BEP and BB studies in weeks 1-4, but this reporting ceased in weeks 5-8 (Table ). An increase in flatulence from the carrots was not expected, as their dietary fiber is less than that of the bean varieties.
Percentage of cross-over trial participants reporting increased flatulence each week by food type
Reports of stool change in frequency or consistency were fewer than for flatulence. For all beans in the Pinto/BEP and BB studies, only 10% of participants reported an increase in stool frequency the first week. Twenty-four percent of the participants eating pinto beans and 10% of those eating vegetarian baked beans reported a change. One to two people reported changes in stool frequency or consistency for black-eyed peas and carrots. Throughout the remaining weeks of the two cross-over studies, only one to two people reported a change in stool frequency. A similar situation was observed for reported bloating, with those participants consuming the pinto beans experiencing the greatest bloating increase in the first week (29%), followed by those eating vegetarian baked beans (14%), and last by those eating carrots (8%) and black-eyed peas (6%) (Table ). Mean ages and BMIs were not significantly different by reported symptoms or lack of symptoms within and across genders. However, women reported stool change more often than men (4.7% vs. 0.3%; p = 0.000).
Percentage of participants reporting increased bloating frequency during each study week by food item consumed for cross-over trials.
For the overall GI symptom variable in the Pinto/BEP study, most participants (88%, n = 15 for pinto beans and 82%, n = 14 for black-eyed peas) reported zero or only one incidence of increased flatulence, stool change or bloating over each 8-week period. Twelve percent (n = 2) and 18% (n = 3) respectively reported two to four incidences of GI discomfort for these two food interventions, but none of the participants reported excessive symptoms, defined as more than five reports of a problem over each 8 week intervention phase. Seventy-two percent (n = 18) of the participants in the BB study reported zero or only one symptom of GI discomfort over the 8-week study period, 16% (n = 4) reported two to four symptoms and 12% (n = 3) reported excessive GI symptoms. All three participants who had excessive GI symptoms with the BB study were men. However, no significant differences were found for the categorical summary variable of symptom reporting with regard to gender, bean type, BMI, or macronutrient intakes, including dietary fiber (Figure ).
Percentage of all reports indicating gastrointestinal symptoms by food type in two randomized cross-over studies.
Dietary intake data obtained from the 24 hour recalls during the cross-over trials Pinto/BEP and BB are shown in Table for each of the baseline, intervention and control phases. There were no significant differences in nutrient intakes with the exception of dietary fiber between the vegetarian baked beans and baseline phases. The fiber content of the pinto beans and the vegetarian baked beans was 7 grams per ½ cup serving. The black-eyed peas contained 4 grams, and the carrots contained 2 grams per ½ cup serving.
Mean nutrient composition of cross-over trial participant's 24-hour dietary recalls during treatment and baseline phases (n = number of food records per phase)
Study 3 - PintoPA
Similar results were observed for pinto beans and flatulence in the PintoPA trial as were seen in the Pinto/BEP cross-over study. Forty-five percent reported increased flatulence with pinto bean consumption during the first week of the study. However, the reported percentage dropped to 38% in the second week and to 30% by the third week. For weeks 6-12, 15-23% continued to report increased flatulence. The canned pinto beans utilized in this trial were identical to those in cross-over study Pinto/BEP. Participants in the control arm of the trial consumed a soup that did not have any known flatulence-producing ingredients. Three to eight percent of control arm participants consistently reported increased flatulence throughout the 12 weeks of the trial (Table ). This rate is similar to that seen for the canned carrots control food in cross-over studies Pinto/BEP and BB. Eight to 20% of the subjects consuming pinto beans reported stool changes across all 12 weeks of the PintoPA study, while1-2 people reported stool changes on the control soup diet. Reports of increased bloating frequency were 25% for the first week, and 40% for the second week for those consuming the pinto bean treatment (Table ). Bloating continued to be reported by 3-5% of the control arm group throughout the 12-week study (Figure ). Dietary intake data from 3-day food records for the participants in the intervention and control arms of the trial are shown in Table . There were no significant differences in intakes between cohorts with the exception of fiber for the control group.
Percentage of parallel arm trial participants reporting increased flatulence each week by food type
Percentage of parallel arm trial participants reporting increased bloating frequency each week by food type
Percentage of all reports indicating gastrointestinal symptoms by food type in parallel arm trial.
Mean nutrient composition of parallel arm participant's 3-day food records during intervention and baseline phases
Reports of GI symptoms were analyzed by gender and age for the pinto beans and the control soup. Mean ages were not significantly different by reported symptoms or lack of symptoms within and across genders. For the participants in the pinto bean trial arm, there were significant differences between women and men with regard to reported symptoms. In these data, women reported bloating (13.1% vs. 4.6%) and stool change (3.4% vs. 1.7%) more often than men (p = 0.000).