Table 1.

Different dietary patterns and their impact on IBS symptoms.

FOODS	MECHANISM OF ACTION	ASSOCIATION WITH IBS	SPECIFIC DIETARY APPROACH
FODMAPs [126]	Poor absorption in small intestine, causing osmotic effect Fermentation in colon, producing gas and attracting water.	High prevalence in IBS → 33% of patients with functional gastrointestinal disorders, including IBS Symptoms associated: Triggers bloating, abdominal discomfort, and altered bowel habits	Low-FODMAP diet to identify triggers: ✓Around 60% of IBS patients have symptom relief ✕Alteration of gut microbiota not fully addressed ✕Inadequate nutrient intake due to the restrictive nature of the diet and risk of restrictive eating habits
Fructose [77]	Malabsorption due to deficiency in fructose transporters Leads to fermentation in colon	Common in IBS patients → The prevalence of fructose intolerance in patients with IBS is about 22% Symptoms associated: Causes bloating, abdominal pain, flatulence, and diarrhea	Fructose-restricted diet (FRD): ✓FRD significantly reduced abdominal pain and discomfort, bloating, and stool frequency, whereas no change was observed for stool consistency ✕Inadequate nutrient intake due to the restrictive nature of the diet and risk of restrictive eating habits
Non-Celiac Gluten Sensitivity [127,128]	Symptoms triggered by gluten without celiac antibodies, villous atrophy, or allergies	Prevalence of NCGS in IBS → between 23 and 49% Symptoms associated: Intestinal and extra-intestinal symptoms (i.e., altered bowel habit, abdominal pain, bloating, headache, fatigue, and joint pain)	Gluten-free diet: ✓Reduction in gastrointestinal symptom severity like bloating and abdominal pain ✕Decreased consumption of carbohydrates and fiber and higher intake of sugar, saturated fats, and sodium. Gluten-free products are more expensive than their gluten-containing equivalents.
Lactose [129,130]	Incomplete digestion due to lactase deficiency Fermentation in colon	Misdiagnosed as IBS → 60.7% of the patients with IBS and 43.5% in the control group Symptoms associated: Triggers bloating and diarrhea after ingestion	Lactose-free diet: ✓Decrease in abdominal pain, bloating, and diarrhea in 59.1% of IBS patients ✕Deficiencies of calcium, vitamin D, and proteins and inadequate intake of calcium, vitamin D, and proteins
Food Additives [131]	Alteration of gut microbiota Induction of inflammation and permeability changes	Potential trigger of IBS onset → Between 1 and 2% of general population, with no direct data on IBS Symptoms associated: Effects on gut health are ongoing	Avoidance of artificial sweeteners, emulsifiers, and colorants: ✓Reduction in processed food intake, typically present in the Western diet ✕No data on IBS available