Table 1. The characteristics of the study population.

Characteristics	PI-IBS (n = 16)	ID-IBS (n = 44)	Healthy Controls (n = 40)
Average age (range)	50 (28–66)	54 (24–79)	53 (25–86)
Ethnicity
Asian	1	0	0
B/AA	5	17	18
H/L	7	10	9
W/C	3	17	13
Gender
Female	13	36	23
Male	3	8	17

IBS patients with underlying conditions that are known to influence gastrointestinal function other than IBS including diabetes, pregnancy, breast feeding, cirrhosis, celiac disease, and inflammatory bowel disease were excluded from the study.

PI-IBS, post-infectious IBS; ID-IBS, idiopathic IBS; B/AA, Black/African-America; H/L, Hispanic/Latino; W/C, White/Caucasian.