Macronutrient intakes in obese subjects with or without small intestinal bacterial overgrowth: an alimentary survey

Obesity is a multifactorial disorder with a possible microbiota derangement in its pathogenesis. Moreover, in obese patients the likelihood of small intestinal bacterial overgrowth (SIBO) is greater than in controls, although few studies are currently available. This study investigates the prevalence of SIBO and the possible role of dietary macronutrients in obesity.

Sixty obese patients and normal lean controls were enrolled for SIBO detection. Diagnosis of SIBO was performed by a glucose breath test. A 24-hour recall questionnaire was administered to investigate macronutrient daily intake between the two obese patient subgroups (with/without SIBO).

The presence of SIBO in obese and controls was respectively 23.3% and 6.6% (p = 0.02, OR = 4.26, 95% Confidence interval = 1.31-13.84). Obese patients with SIBO ingested more carbohydrates (252.75 ± 30.53 vs 201 ± 70.76 g/day, p = 0.01), more refined sugars (104.15 ± 28.69 vs 73.32 ± 44.93 g/day, p = 0.02) and less total and insoluble fibers (9.6 ± 1.97 vs 14.65 ± 8.80 g/day, p = 0.04 and 4.7 ± 1.11 vs 8.82 ± 5.80 g/day, p = 0.01, respectively). There were no significant differences in lipid and protein intake between the two groups.

SIBO is widespread in obese subjects. Carbohydrates might promote the development of SIBO in obesity and fibers provide a protective function. Our results suggest a close relationship between diet and SIBO in obesity, thus supporting a possible role for intestinal microbiota.