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Food is a major trigger of gastrointestinal symptoms in IBS

In recent years, adverse reactions to specific food components have surged within Western populations. 84% of patients with IBS perceive eating any food as a trigger to their gastrointestinal distress. Among the primary dietary culprits responsible for symptoms such as bloating, abdominal distension, pain, and altered bowel habits (constipation or diarrhea), carbohydrates—specifically FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols)—, and foods rich in biogenic amines and fatty foods, play a significant role1.

Gastrointestinal symptoms associated with carbohydrate malabsorption primarily arise from two mechanisms involved in the acute effects in the gastrointestinal tract. Firstly, when carbohydrates are inadequately digested and absorbed, they serve as a substrate for intestinal bacteria, fostering bacterial fermentation. This results in excessive production of hydrogen, methane, and carbon dioxide, contributing to bloating and abdominal distension. Secondly, a diet rich in unabsorbed sugars increases the osmotic load in the intestinal lumen, leading to accelerated food transit and diarrhea2.

In addition, a high FODMAP diet may lead to an increased abundance of Gram-negative bacteria, which drives an increase in luminal pro-inflammatory lipopolysaccharide that eventually increases barrier loss and mast cell activation involved in the increased visceral hypersensitivity seen in most patients with IBS3.

 

Mechanisms by which FODMAPs might impact gut function

FODMAPs are short-chain carbohydrates, including lactose, excess fructose, polyols, fructans, fructo-oligosaccharides (FOS), and galacto-oligosaccharides (GOS). These compounds are naturally found in a variety of foods, such as fruits, vegetables, cereals, legumes, dairy products, and sweeteners4.

Due to slow transport mechanisms or ineffective enzymatic activity, they are poorly absorbed in the small intestine. Upon ingestion, they remain partially undigested and reach the colon, where they are fermented by the gut microbiota, producing gas and drawing in water via osmotic effects. This process contributes to bloating, visceral hypersensitivity, abdominal pain, and transit disturbances, particularly diarrhea, in predisposed individuals.

 

The low-FODMAP diet: clinical benefits and potential drawbacks

Several reviews and meta-analyses have demonstrated that a low-FODMAP diet (LFD) significantly improves overall symptoms in all IBS subtypes5. Studies indicate that LFD is superior to control diets in sensitive individuals, particularly in alleviating bloating and abdominal pain while promoting normalization of bowel habits, reducing both diarrhea and constipation6-9.

However, despite these benefits, a LFD is not without potential long-term consequences. Research has highlighted concerns regarding the nutritional adequacy of this diet, especially when followed without professional guidance. Common deficiencies include reduced fiber intake due to limited consumption of plant-based foods. Additionally, excessive exclusion of dairy products may lead to lower calcium, folate, and riboflavin levels. Vitamin C deficiency is also a concern when vegetable and fruit intake is overly restricted10,11.

Another critical aspect is the impact of a LFD on gut microbiota diversity. Studies indicate that LFD can exacerbate gut microbiota imbalances, leading to a significant reduction in beneficial bacterial genera such as Bifidobacterium. However, the effects of the low FODMAP diet on other taxa and alpha diversity was not consistent and no effects was observed on individual and total short-chain fatty acids and fecal pH12.

 

Probiotics for managing carbohydrate intolerances

A promising adjunct to dietary management is the use of strain-specific probiotics, which may help modulate the gut microbiota in patients with IBS. By reducing gas-producing bacterial species, probiotics could alleviate symptoms associated with carbohydrate malabsorption. Furthermore, probiotics may enhance micronutrient absorption, increasing the bioavailability of essential vitamins and minerals at the intestinal level13,14.

Specific probiotics have shown efficacy in improving lactose digestion and absorption. Lactose intolerance, one of the most common disaccharidase deficiencies (affecting lactase, sucrase, and maltase enzymes), manifests as abdominal pain, bloating, and diarrhea upon lactose consumption15. Lactase deficiency (hypolactasia) promotes lactose fermentation by gut bacteria, exacerbating fermentative dysbiosis and leading to discomfort and osmotic diarrhea.16 Certain Lactobacillus species demonstrate a beneficial effect due to their genomic ability to produce beta-galactosidase, an enzyme essential for lactose degradation17.

Probiotics may also help offset gut microbiota changes seen on a low FODMAP diet. The coadministration of a specific probiotic blend with a mixture of Lactobacillus, Bifidobacterium, and Streptococcus species together with a low FODMAP diet was also successful in increasing the number of Bifidobacterium species in the fecal microbiome decreased with the low FODMAP diet in adult patients with IBD18.

 

Conclusion

An integrative approach that combines adherence to a low-FODMAP diet with strain-specific probiotics may offer an effective strategy for managing symptoms associated with carbohydrate malabsorption, including FODMAP and lactose intolerance. This dual approach can improve gastrointestinal symptoms in FGID patients, particularly those with IBS, while also fostering gut microbial balance and mitigating the adverse effects of dietary restriction on microbiota diversity.

 

References:

  1. Zingone F, Bertin L, Maniero D, et al. Myths and Facts about Food Intolerance: A Narrative Review. Nutrients. 2023; 15(23):4969. doi: 10.3390/nu15234969.
  2. Omer A, Quigley EMM. Carbohydrate Maldigestion and Malabsorption. Clin Gastroenterol Hepatol. 2018; 16(8):1197-1199. doi: 10.1016/j.cgh.2018.01.048.
  3. Singh P, Tuck C, Gibson PR, et al. The role of food in the treatment of bowel disorders: focus on irritable bowel syndrome and functional constipation. Am J Gastroenterol. 2022; 117(6):947-957. doi: 14309/ajg.0000000000001767.
  4. Ispiryan L, Zannini E, Arendt EK. FODMAP modulation as a dietary therapy for IBS: Scientific and market perspective. Compr Rev Food Sci Food Saf. 2022 Mar;21(2):1491-1516. doi: 10.1111/1541-4337.12903.
  5. Dean G, Chey SW, Singh P, et al. A diet low in fermentable oligo-, di-, monosaccharides and polyols improves abdominal and overall symptoms in persons with all subtypes of irritable bowel syndrome. Neurogastroenterol Motil. 2024; 36(8):e14845. doi: 10.1111/nmo.14845
  6. Holtmann G, Shah A, Morrison M. Pathophysiology of Functional Gastrointestinal Disorders: A Holistic Overview. Dig Dis. 2017;35 Suppl 1:5-13. doi: 10.1159/000485409.
  7. Carbone F, Van den Houte K, Besard L, et al. Diet or medication in primary care patients with IBS: the DOMINO study – a randomised trial supported by the Belgian Health Care Knowledge Centre (KCE Trials Programme) and the Rome Foundation Research Institute. Gut. 2022;71(11):2226-2232. doi:10.1136/gutjnl-2021-325821
  8. Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology. 2014;146(1):67-75.e5. doi:10.1053/j.gastro.2013.09.046
  9. Algera JP, Demir D, Törnblom H, Nybacka S, Simrén M, Störsrud S. Low FODMAP diet reduces gastrointestinal symptoms in irritable bowel syndrome and clinical response could be predicted by symptom severity: A randomized crossover trial. Clin Nutr. 2022;41(12):2792-2800. doi:10.1016/j.clnu.2022.11.001
  10. Sultan N, Varney JE, Halmos EP, et al. How to Implement the 3-Phase FODMAP Diet Into Gastroenterological Practice. J Neurogastroenterol Motil. 2022;28(3):343-356. doi:10.5056/jnm22035
  11. Bellini M, Tonarelli S, Nagy AG, et al. Low FODMAP Diet: Evidence, Doubts, and Hopes. Nutrients. 2020;12(1):148. Published 2020 Jan 4. doi:10.3390/nu12010148
  12. So D, Loughman A, Staudacher HM. Effects of a low FODMAP diet on the colonic microbiome in irritable bowel syndrome: a systematic review with meta-analysis. Am J Clin Nutr. 2022;116(4):943-952. doi:10.1093/ajcn/nqac176
  13. Markowiak P, Śliżewska K. Effects of Probiotics, Prebiotics, and Synbiotics on Human Health. Nutrients. 2017;9(9):1021. Published 2017 Sep 15. doi:10.3390/nu9091021
  14. Barkhidarian B, Roldos L, Iskandar MM, Saedisomeolia A, Kubow S. Probiotic Supplementation and Micronutrient Status in Healthy Subjects: A Systematic Review of Clinical Trials. Nutrients. 2021;13(9):3001. Published 2021 Aug 28. doi:10.3390/nu13093001
  15. Bayless TM, Brown E, Paige DM. Lactase Non-persistence and Lactose Intolerance. Curr Gastroenterol Rep. 2017;19(5):23. doi:10.1007/s11894-017-0558-9
  16. Deng Y, Misselwitz B, Dai N, Fox M. Lactose Intolerance in Adults: Biological Mechanism and Dietary Management. Nutrients. 2015;7(9):8020-8035. Published 2015 Sep 18. doi:10.3390/nu7095380
  17. Ahn SI, Kim MS, Park DG, Han BK, Kim YJ. Effects of probiotics administration on lactose intolerance in adulthood: A meta-analysis. J Dairy Sci. 2023;106(7):4489-4501. doi:10.3168/jds.2022-22762
  18. Staudacher HM, Lomer MCE, Farquharson FM, et al. A Diet Low in FODMAPs Reduces Symptoms in Patients With Irritable Bowel Syndrome and A Probiotic Restores Bifidobacterium Species: A Randomized Controlled Trial. Gastroenterology. 2017;153(4):936-947. doi:10.1053/j.gastro.2017.06.010