Table 2.

Characteristics of observational studies included in the qualitative synthesis

First author, year (country)	Study design	Number of subjects	Diagnostic criteria	Age (years)	Female (%)	Predominant IBS subtype (%)	Quality assessmenta (number of starsb)	Results
Lee, 2019 [18] (South Korea)	Cross-sectional	393	Validated modified Korean Rome III	49.4	61.8	IBS-D (43.6)	Poor (3)	High-FODMAP foods were reported by 43.5% of controlsc and 63.4% of IBS subjects to induce GI symptoms
Pourmand, 2018 [51] (Iran)	Cross-sectional	3362 (number of confirmed IBS cases NR)	Unvalidated modified Persian Rome III	NR	NR	NR	Good (7)	No significant association was found between adherence to the LFD and IBS prevalence

The data are represented as mean value unless indicated otherwise

FODMAP fermentable oligo-, di-, monosaccharides, and polyols; IBS-D irritable bowel syndrome with diarrhea; LFD low-FODMAP diet; NR not reported

^aAccording to an adapted Newcastle–Ottawa scale for cross-sectional studies [48]

^bOn a scale from 0 to 10

^cThe control group comprised of symptomatic and nonsymptomatic subjects