An Evidence-based Approach to Dietary Treatment of Irritable Bowel Syndrome

Transcription

1 An Evidence-based Approach to Dietary Treatment of Irritable Bowel Syndrome American College of Gastroenterology August 2014, Indianapolis Brian E. Lacy, Ph.D., M.D. Professor of Medicine, Geisel School of Medicine at Dartmouth Chief, Section of Gastroenterology & Hepatology Dartmouth-Hitchcock Medical Center, Lebanon NH 1

2 Why is this important? IBS is defined by symptoms not biomarkers Symptoms of IBS can be confusing Symptoms of IBS can overlap with other FGIDs Other diseases have symptoms that mimic IBS IBS is prevalent IBS affects your patients Why is this important now? IBS can be hard to treat Medications Complementary therapies Behavioral therapies Psychological therapies Patients are instituting dietary Tx on their own Some diets are expensive; others are dangerous 2

3 Diet largely ignored Lack of training Lack of data Lack of interest Treatments for IBS Food & IBS Symptoms: A patient s perspective 60% of patients report worsening of symptoms after meals 1 Survey of 1242 IBS patients the following interventions improved symptoms 2 small meals (69%) avoiding fat (64%) increasing fiber (58%) avoiding milk products (54%) 1 Chey et al, Am J Gastroenterol 2002; 2 Halpert et al, Am J Gastroenterol

4 IBS Etiology: Patients Beliefs % of Patients Die t Up bringin g Environmental Exposures Genetic Food Allerg y/in tole rance Change in Routin e De pressio n A nxie ty Lacy et al, Am J Gastroenterol 2006 Allergy Do I have a Food Allergy? First considered as a cause of GI symptoms in 1916 Loveless described milk allergy in Intolerance adverse reaction; nonimmunologic Aversion psychological avoidance to a specific food or foods Loveless MH. J Allergy,

5 Do I Have a Food Allergy? 30-50% of GI clinic patients believe their symptoms represent a food allergy/intolerance 1 True food allergies are uncommon 1-3% Symptoms develop after eating More common in atopic individuals IgE mediated (type 1) rapid in onset Cell mediated (type 4) delayed hypersensitivity Worst offenders: Peanuts, tree nuts, eggs cow s milk, soy, wheat, fish, shellfish 1 Bhat et al, APT 2002 Or, Do My Symptoms Represent a Food Intolerance? Population study of 20,000 adults 20% complained of ffood intolerance 1 Double-blind challenge, 11.4%-27.4% of patients had a positive reaction Women reported more symptoms; increased prevalence of reactions to food challenge Prevalence rates of food intolerance in IBS patients range from 20-67% 2,3 1 Young et al, Lancet 1994; 2 Simren et al, Digestion 2001; 3 Bhat et al, APT

6 Why might Food cause Symptoms? Stimulation of mechanoreceptors Stimulation of chemoreceptors Release of hormones/peptides Alterations in secretion Changes in osmolarity Fermentation of foods Subsequent luminal distention Solids Luminal Distension Volume, fiber intake, bacterial load Liquids Absorption, secretion, osmotic load Gas Bacterial lfermentation ti Impaired transit Impaired evacuation 6

7 IBS & Foods: Common Offenders Lactose Fructose Non-absorbable sugars Fiber Wheat Other fermentable foods Disaccharide Lactose Broken down into glucose and galactose Lactase deficiency leads to fermentation in the colon Excess hydrogen, CO 2, methane 7

8 Monosaccharide Fructose Exists as a free hexose or after sucrose hydrolysis No enzyme present in human small intestine Fruits, honey, table sugar High fructose corn syrup Very poorly absorbed by itself (GLUT-5) Efficiently absorbed in conjunction with glucose (GLUT-2) Gluten Gluten a storage protein in wheat, barley, rye Genetically susceptible individuals (HLA-DQ2 and HLA-DQ8) develop an immune response Worldwide prevalence in IBS patients = 4% 1 US prevalence in IBS patients = 0.4% 2 1 cite; 2 Cash et al, Gastroenterology

9 Wheat & IBS Gluten-related disorders Celiac disease Dermatitis herpetiformis Gluten ataxia Non-celiac gluten sensitivity Other Fermentable Foods Fructans (fructo-oligosaccharides) Long chains of fructose molecules Galactans (galacto-oligosaccharides) Short chains of sucrose and galactose Raffinose Polyols Sorbitol - Mannitol Xylitol - Maltitol 9

10 Treatment Options Dietary Interventions All or none approach Step-by-step Avoid fad diets use evidence where available Antibiotics Probiotics Prokinetics Other agents Elimination Diet First described in consecutive IBS patients t 1 week (single meat, single fruit, water) Jones et al. noted improvement in 14/21 Pts Other studies: no benefit No standardization Variety of inclusion/exclusion criteria Lack of pre-defined outcomes Jones et al, Lancet

11 Lactose-free Diet 30-35% of US adults are lactose intolerant Prevalence in IBS patients is slightly higher Worldwide prevalence of lactose intolerance = 70% Goal: maintain calcium, Vitamin D Diagnosis: breath test, challenge, elimination Treatment options Dairy free - Hemp Lactaid - Soy Rice - Quinoa Almond - Oat Cocoanut Fructose-Free Diet Fructose intolerance estimated at 11-70% 1 In IBS patients 40% may be fructose intolerant 2 50% reduction in symptoms in 2/3 of patients with functional bloating 3 Minimize Ingest with glucose Avoid 1 Ravich et al, Gastroenterology 1983; 2Gibson et al APT 2007; 3cite 11

12 Low-Fiber Diet Likely more helpful in IBS-D or IBS-M Step-wise < 25 grams < 20 grams < 15 grams All at once Focus on lean proteins & simple carbohydrates Gluten-free Diet Avoid wheat (sounds easy) Absence of fructans and galactans may also help Safe foods: Rice Potato Corn (but watch fructose) Oats Quinoa 12

13 IBS & Diet Low carbohydrate Low fructose/fructan Low gluten Low FODMAP (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyol) Low Carbohydrate Diet Prospective, randomized, controlled study 17 moderate-severe IBS-D patients t 4-week very low carbohydrate diet (VLCD) 51% fat; 45% protein; 4% carbohydrate Endpoint: adequate relief for > 2 weeks 13 completed the study All 13 met the responder definition 10 experienced adequate relief for all 4 weeks Austin et al, Clin Gastro & Hepatol

14 Low Carbohydrate Diet Secondary Endpoints also improved Decrease in stool frequency Improvement in stool consistency Decreased abdominal pain Improvement in quality-of-life IBS & Low Fructose/Fructan Diet 26 IBS patients with fructose malabsorption (Rome II; + breath test; mean age = 38) Prior response to low fructose/low fructan diet Randomly re-challenged with offending foods 70% of those receiving fructose, 77% receiving fructans, and 79% receiving a mixture noted return/worsening of symptoms compared to glucose (14%; p < 0.002) Sheperd et al, Clin Gastroenterol Hepatol 2008; 6:

15 IBS & Low Gluten R, DB, PC, re-challenge study 34 IBS patients (Rome III); celiac excluded Prior improvement in Sx on gluten-free diet 16 gm of non-fermentable gluten/day vs. 16 grams of gluten Primary endpoint: adequate symptom relief Gluten-group had less improvement in Sx than those on gluten-free (68% vs. 40%; p =.001) Biesiekierski et al, Am J Gastro 2011 IBS & low FODMAP Diet Fermentable Oligosaccharides, Disaccharides, Monosaccharides, and Polyols Avoid Fructans (onions, peppers, artichokes) Avoid Fructose (fruits, honey, juices, soda) Avoid Galacto-oligosaccharides (legumes, lentils, chickpeas, kidney beans) Avoid Polyols (sugar-free candies, apples, watermelon, mushrooms) 15

16 IBS & Low FODMAP Diet: Or, what is there left to eat? Lean proteins Gluten-free breads, rolls, pasta Rice, corn, oat products Quinoa Safe fruits and vegetables: Snow peaks, bok choy, mandarin oranges IBS & Low FODMAP Diet: Some Problems Exist What is the cut-off for FODMAP content? Resources differ on low FODMAP diets Total meal FODMAPs should be counted, not individual FODMAP 16

17 IBS: Prospective study to Evaluate Low FODMAP diet 82 consecutive IBS patients (NICE criteria) Detailed symptom and dietary evaluation 9 month evaluation performed in UK Individual symptoms and global IBS symptoms measured 39 in the standard diet group 42 in the low FODMAP diet group Staudacher et al, J Hum Nutr Diet, 2011 IBS Symptom Improvement: Low FODMAP Diet vs. Standard Diet Bloating (82% vs. 49%) Abdominal pain (85% vs. 61%) Flatulence (87% vs. 50%) Nausea (67% vs. 29%) Diarrhea (83% vs. 62%; ns) Composite symptom score (86% vs. 49%) 17

18 IBS & Diet: Conclusions Educate your patients Don t forget the obvious (lactose & fructose) Consider low FODMAP diet Discuss gluten-free diet For IBS-D, consider VLCD More research is desperately needed 18