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Dear colleagues and friends,
Thank you for your continued interest and support of the Perspectives debates. In this edition, Dr. Ashwin Ananthakrishnan and Dr. Laura Raffals explore the controversial topic of diet-based therapy in inflammatory bowel disease, highlights of the rationales for and against, and the current state of the evidence. All gastroenterologists frequently face questions pertaining to diet and its purported effects on digestive health. I found the discussion relevant to my own general practice, and I hope you will enjoy reading it as much as I did. As always, I welcome your comments and suggestions for future topics at [email protected].
Charles Kahi, MD, MS, AGAF, professor of medicine, Indiana University, Indianapolis. He is also an associate editor for GI & Hepatology News.
IBD can be treated with diet alone
Inflammatory bowel diseases (IBD), comprising Crohn’s disease and ulcerative colitis, have emerged as global diseases. The past 3 decades have seen a rising incidence of these diseases not just in the Western hemisphere, where their prevalence has been well recognized, but also in regions of the world such as Asia and South America where they were previously rare. Whereas several possible factors have been proposed to explain this rising incidence and globalization of disease with varying degrees of supportive evidence, one of the most likely factors is a changing diet. Over the same period that the disease incidence and prevalence have risen, diets worldwide have converged with several common trends observed across countries and continents. These include reductions in dietary fiber, fruits, and vegetables, and increased intake of processed food, animal protein, fats, and sugary drinks, all of which have been linked epidemiologically to Crohn’s disease.
Treatment of Crohn’s disease and ulcerative colitis over the past 2 decades has focused on the immunologic dysfunction observed in these patients. Successful treatment has relied on suppressing immune responses either broadly or through targeted suppression of specific immunologic pathways. By and large, whereas these approaches have enabled us to make significant progress in reducing disease-related morbidity, success has been moderate at best, with fewer than half of patients in any clinical trial achieving remission at the end of a year. Thus, this approach alone may not be sufficient for most patients with IBD.
Treatment of IBD with diet was long considered out of the mainstream and confined to the realm of anecdotes and message boards. Despite most patients believing that diet played a role in development of IBD and onset of flares and that dietary modification was helpful in relieving symptoms, physicians – who for the most part were not trained in these approaches – were not believers, and probably rightly so in the absence of any supporting data.1 However, the parallel emergence of three bodies of literature has now brought diet back into the mainstream of IBD care (such that not a single IBD conference goes by without at least a session or two on diet). First, large prospective cohorts from Europe and North America provided robust evidence linking long-term adult dietary patterns to disease incidence in adult-onset IBD, which supports many important case-control observations made over the past 2 decades.2 Second, and perhaps most important, we began understanding the role of the microbiome in the development of these diseases and recognizing its centrality to bowel inflammation. One of the key determinants of the microbiome is diet, exerting both short-term and long-term influences on the microbial structure. While microbial changes are by no means the only mechanism through which diet can influence intestinal inflammation, they are among the most important, with broad effects across many dietary components. These findings provided a robust scientific basis for investigating the role of diet. Third, while still far from the high-quality (and expensive) set-up of investigational trials of pharmacologic therapies, dietary therapy studies have also evolved to randomized controlled trial designs and investigation of mechanism-driven dietary combinations. Together, I think these three recent advances, in addition to the wealth of existing literature and anecdotal experience, have been important in moving diet (back) into the IBD mainstream.
So what evidence is there that diet is effective in the treatment of IBD? Randomized controlled trials published more than a decade ago demonstrated that exclusive enteral nutrition, wherein all table foods are eliminated from a diet and the patient relies on an elemental diet alone for nutrition, was effective in not just inducing clinical remission but also improving inflammatory biomarkers.3 With results replicated in several trials, exclusive enteral nutrition is, in many parts of the world, one of the first-line treatments for pediatric Crohn’s disease. That this has not been translated to longer-term maintenance therapy is not necessarily an indicator of lack of durable efficacy, but reflects the challenges of maintaining such a restrictive diet long term while living an active, normal life. However, more recent rigorous studies have demonstrated that the effects of exclusive enteral nutrition can be mimicked either by a selected, less-restrictive diet (such as CD-TREAT4), which is more sustainable, or by combining partial enteral nutrition with an elimination diet that is quite diverse (such as CDED5). The latter two are considerably more promising as longer-term dietary treatments for Crohn’s disease with durable efficacy in open-label studies and randomized trials.
What are my final arguments for diet being used as a treatment for IBD? With the exception of very restrictive ones, diets are generally safe. Of course, patients on restricted diets need monitoring for nutritional deficiencies, but this monitoring is likely less intense than that needed for many of our immunosuppressive therapies. Dietary therapies are not associated with an increase in risk of infections or malignancy (unlike our traditional immunosuppressive therapies), and consequently are much more likely to be accepted by our patients than what we are currently offering. In addition, the existing treatments are expensive and consequently difficult to sustain globally with the increasing burden of these diseases. On the other hand, as eating and dietary choices are a routine part of day-to-day life, dietary therapies are not likely to be associated with any excess costs.
Therefore, treating IBD with diet alone is supported by epidemiologic, mechanistic, and clinical evidence and is a safe, effective, and inexpensive alternative for our patients.
References
1. Zallot C et al. Inflamm Bowel Dis. 2013 Jan;19(1):66-72.
2. Sasson AN et al. Clin Gastroenterol Hepatol. 2019 Dec 5;S1542-3565(19)31394-1.
3. Wall CL et al. World J Gastroenterol. 2013;19:7652-60.
4. Svolos V et al. Gastroenterology. 2019;156:1354-67.e6.
5. Levine A et al. Gastroenterology. 2019;157:440-50.e8.
Dr. Ananthakrishnan is a gastroenterologist in the division of gastroenterology, Crohn’s and Colitis Center, Massachusetts General Hospital and Harvard Medical School, Boston. He is supported by funding from the Crohn’s and Colitis Foundation and the Chleck Family Foundation.
IBD can be treated with diet alone – No, it cannot!
The cause of IBD is not completely understood, but we believe something in our environment triggers a dysregulated immune response in individuals with a genetic predisposition to IBD. Among the environmental triggers commonly recognized, diet is considered an important trigger through its ability to affect the composition and health of the gut microbiome and host barrier function. Epidemiologic data support this assumption. Westernization of diet has been associated with the increasing incidence of IBD across the globe and in immigrants who move from developing countries to an industrialized country. Observational studies have shown diets higher in meat and polyunsaturated fatty acids and omega-6 fatty acids are associated with a higher risk for IBD, whereas diets high in fruits, vegetables, and other sources of dietary fiber have a lower risk of IBD.
A growing body of evidence supports the impact food can have on gut health, specifically in mouse IBD models, but it is challenging to translate findings from animal studies into dietary interventions for IBD patients. Mouse studies help us understand the mechanistic basis of how diet may affect IBD, but randomized clinical trials establishing their role in IBD are lacking. This is not surprising as dietary studies are challenging, particularly if done in a robust manner, given the difficulties of ensuring and measuring dietary compliance.
Exclusive enteral nutrition (EEN) has been studied the most rigorously of all diets in IBD and has demonstrated the greatest benefit, compared with other diet studies in IBD. EEN requires the intake of elemental, semi-elemental, or polymeric formulas to meet all nutritional requirements without additional intake of food for 6-8 weeks. Studies have been performed mostly in pediatric populations and have shown effectiveness in induction of remission with reduction in inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin, and even mucosal healing. EEN has not worked out as well for adult populations, because of the poor tolerability of exclusive intake of enteral formulas. Because of this limitation, studies of partial enteral nutrition have been performed that generally allow some food intake in addition to the enteral nutrition. When compared with EEN or anti–tumor necrosis factor–alpha therapy, partial enteral nutrition is a less-effective treatment of Crohn’s disease; however, partial enteral nutrition does appear to improve clinical symptoms.
Beyond EEN, there are many diets that have been considered for the treatment of IBD, including the specific carbohydrate diet (SCD), Crohn’s disease exclusion diet, autoimmune diet, low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols), Paleolithic diet, Mediterranean diet, and the semi-vegetarian diet, to name a few. Of these, only the SCD and Crohn’s disease exclusion diets have shown improvement in clinical remission and reduction in inflammatory markers.
The SCD diet is based on the theory that malabsorption of disaccharide and polysaccharide carbohydrates leads to bacterial overgrowth and host barrier dysfunction. This diet eliminates grains, dairy, processed meats, and certain vegetables such as potatoes, yams, and legumes. Small uncontrolled studies have shown improvement in symptoms and endoscopy findings. However, this restrictive diet is nearly impossible to follow long term. The Crohn’s disease exclusion diet is a whole foods diet avoiding all processed foods, animal fats, dairy, and gluten. Small studies of this diet have also shown improvement in clinical symptoms and inflammatory markers.
The plethora of studies and reports of the therapeutic effect of diet on IBD provide some promise of the benefit dietary modifications can bring to our IBD patients. However, most dietary studies are underpowered, lack a control arm, and do not include endoscopic endpoints. The current body of evidence remains insufficient to support the use of diet alone for the treatment of IBD. We need randomized clinical controlled trials that are held to the same rigor as those of our approved medical treatments for IBD. Although such trials are challenging, we’ve seen groups rise to the task to carry out more robust dietary studies in the IBD population, and we await the results of several ongoing trials.
IBD is a challenging disease to live with and often leaves our patients feeling out of control. Dietary choices provide an avenue for patients to have some control of their health. However, current evidence does not support the prescription of dietary interventions alone to treat IBD, particularly when we have known, effective therapies. While I am not ready to prescribe diet as a stand-alone treatment for IBD, I make a point to discuss the role diet may play in helping our patients achieve optimal health. As health care providers, it is our responsibility to provide holistic care to our patients, which includes promotion of a healthy diet, absent processed foods and added sugars. Healthy lifestyle choices combined with effective medical and surgical treatments offer our patients the best shot at sustained disease control.
References
1. Hou JK et al. Am J Gastroenterol. 2011;106(4):563-73.
2. Zachos M et al. Cochrane Database Syst Rev. 2007(1):CD000542.
3. Lee D et al. Inflamm Bowel Dis. 2015;21(8):1786-93.
4. Obih C et al. Nutrition. 2016;32(4):418-25.
5. Sigall Boneh R et al. J Crohns Colitis. 2017;11(10):1205-12.
Dr. Raffals is a gastroenterologist in the division of gastroenterology and hepatology, Mayo Clinic, Rochester, Minn. She has no financial conflicts of interest relevant to this paper.
Dear colleagues and friends,
Thank you for your continued interest and support of the Perspectives debates. In this edition, Dr. Ashwin Ananthakrishnan and Dr. Laura Raffals explore the controversial topic of diet-based therapy in inflammatory bowel disease, highlights of the rationales for and against, and the current state of the evidence. All gastroenterologists frequently face questions pertaining to diet and its purported effects on digestive health. I found the discussion relevant to my own general practice, and I hope you will enjoy reading it as much as I did. As always, I welcome your comments and suggestions for future topics at [email protected].
Charles Kahi, MD, MS, AGAF, professor of medicine, Indiana University, Indianapolis. He is also an associate editor for GI & Hepatology News.
IBD can be treated with diet alone
Inflammatory bowel diseases (IBD), comprising Crohn’s disease and ulcerative colitis, have emerged as global diseases. The past 3 decades have seen a rising incidence of these diseases not just in the Western hemisphere, where their prevalence has been well recognized, but also in regions of the world such as Asia and South America where they were previously rare. Whereas several possible factors have been proposed to explain this rising incidence and globalization of disease with varying degrees of supportive evidence, one of the most likely factors is a changing diet. Over the same period that the disease incidence and prevalence have risen, diets worldwide have converged with several common trends observed across countries and continents. These include reductions in dietary fiber, fruits, and vegetables, and increased intake of processed food, animal protein, fats, and sugary drinks, all of which have been linked epidemiologically to Crohn’s disease.
Treatment of Crohn’s disease and ulcerative colitis over the past 2 decades has focused on the immunologic dysfunction observed in these patients. Successful treatment has relied on suppressing immune responses either broadly or through targeted suppression of specific immunologic pathways. By and large, whereas these approaches have enabled us to make significant progress in reducing disease-related morbidity, success has been moderate at best, with fewer than half of patients in any clinical trial achieving remission at the end of a year. Thus, this approach alone may not be sufficient for most patients with IBD.
Treatment of IBD with diet was long considered out of the mainstream and confined to the realm of anecdotes and message boards. Despite most patients believing that diet played a role in development of IBD and onset of flares and that dietary modification was helpful in relieving symptoms, physicians – who for the most part were not trained in these approaches – were not believers, and probably rightly so in the absence of any supporting data.1 However, the parallel emergence of three bodies of literature has now brought diet back into the mainstream of IBD care (such that not a single IBD conference goes by without at least a session or two on diet). First, large prospective cohorts from Europe and North America provided robust evidence linking long-term adult dietary patterns to disease incidence in adult-onset IBD, which supports many important case-control observations made over the past 2 decades.2 Second, and perhaps most important, we began understanding the role of the microbiome in the development of these diseases and recognizing its centrality to bowel inflammation. One of the key determinants of the microbiome is diet, exerting both short-term and long-term influences on the microbial structure. While microbial changes are by no means the only mechanism through which diet can influence intestinal inflammation, they are among the most important, with broad effects across many dietary components. These findings provided a robust scientific basis for investigating the role of diet. Third, while still far from the high-quality (and expensive) set-up of investigational trials of pharmacologic therapies, dietary therapy studies have also evolved to randomized controlled trial designs and investigation of mechanism-driven dietary combinations. Together, I think these three recent advances, in addition to the wealth of existing literature and anecdotal experience, have been important in moving diet (back) into the IBD mainstream.
So what evidence is there that diet is effective in the treatment of IBD? Randomized controlled trials published more than a decade ago demonstrated that exclusive enteral nutrition, wherein all table foods are eliminated from a diet and the patient relies on an elemental diet alone for nutrition, was effective in not just inducing clinical remission but also improving inflammatory biomarkers.3 With results replicated in several trials, exclusive enteral nutrition is, in many parts of the world, one of the first-line treatments for pediatric Crohn’s disease. That this has not been translated to longer-term maintenance therapy is not necessarily an indicator of lack of durable efficacy, but reflects the challenges of maintaining such a restrictive diet long term while living an active, normal life. However, more recent rigorous studies have demonstrated that the effects of exclusive enteral nutrition can be mimicked either by a selected, less-restrictive diet (such as CD-TREAT4), which is more sustainable, or by combining partial enteral nutrition with an elimination diet that is quite diverse (such as CDED5). The latter two are considerably more promising as longer-term dietary treatments for Crohn’s disease with durable efficacy in open-label studies and randomized trials.
What are my final arguments for diet being used as a treatment for IBD? With the exception of very restrictive ones, diets are generally safe. Of course, patients on restricted diets need monitoring for nutritional deficiencies, but this monitoring is likely less intense than that needed for many of our immunosuppressive therapies. Dietary therapies are not associated with an increase in risk of infections or malignancy (unlike our traditional immunosuppressive therapies), and consequently are much more likely to be accepted by our patients than what we are currently offering. In addition, the existing treatments are expensive and consequently difficult to sustain globally with the increasing burden of these diseases. On the other hand, as eating and dietary choices are a routine part of day-to-day life, dietary therapies are not likely to be associated with any excess costs.
Therefore, treating IBD with diet alone is supported by epidemiologic, mechanistic, and clinical evidence and is a safe, effective, and inexpensive alternative for our patients.
References
1. Zallot C et al. Inflamm Bowel Dis. 2013 Jan;19(1):66-72.
2. Sasson AN et al. Clin Gastroenterol Hepatol. 2019 Dec 5;S1542-3565(19)31394-1.
3. Wall CL et al. World J Gastroenterol. 2013;19:7652-60.
4. Svolos V et al. Gastroenterology. 2019;156:1354-67.e6.
5. Levine A et al. Gastroenterology. 2019;157:440-50.e8.
Dr. Ananthakrishnan is a gastroenterologist in the division of gastroenterology, Crohn’s and Colitis Center, Massachusetts General Hospital and Harvard Medical School, Boston. He is supported by funding from the Crohn’s and Colitis Foundation and the Chleck Family Foundation.
IBD can be treated with diet alone – No, it cannot!
The cause of IBD is not completely understood, but we believe something in our environment triggers a dysregulated immune response in individuals with a genetic predisposition to IBD. Among the environmental triggers commonly recognized, diet is considered an important trigger through its ability to affect the composition and health of the gut microbiome and host barrier function. Epidemiologic data support this assumption. Westernization of diet has been associated with the increasing incidence of IBD across the globe and in immigrants who move from developing countries to an industrialized country. Observational studies have shown diets higher in meat and polyunsaturated fatty acids and omega-6 fatty acids are associated with a higher risk for IBD, whereas diets high in fruits, vegetables, and other sources of dietary fiber have a lower risk of IBD.
A growing body of evidence supports the impact food can have on gut health, specifically in mouse IBD models, but it is challenging to translate findings from animal studies into dietary interventions for IBD patients. Mouse studies help us understand the mechanistic basis of how diet may affect IBD, but randomized clinical trials establishing their role in IBD are lacking. This is not surprising as dietary studies are challenging, particularly if done in a robust manner, given the difficulties of ensuring and measuring dietary compliance.
Exclusive enteral nutrition (EEN) has been studied the most rigorously of all diets in IBD and has demonstrated the greatest benefit, compared with other diet studies in IBD. EEN requires the intake of elemental, semi-elemental, or polymeric formulas to meet all nutritional requirements without additional intake of food for 6-8 weeks. Studies have been performed mostly in pediatric populations and have shown effectiveness in induction of remission with reduction in inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin, and even mucosal healing. EEN has not worked out as well for adult populations, because of the poor tolerability of exclusive intake of enteral formulas. Because of this limitation, studies of partial enteral nutrition have been performed that generally allow some food intake in addition to the enteral nutrition. When compared with EEN or anti–tumor necrosis factor–alpha therapy, partial enteral nutrition is a less-effective treatment of Crohn’s disease; however, partial enteral nutrition does appear to improve clinical symptoms.
Beyond EEN, there are many diets that have been considered for the treatment of IBD, including the specific carbohydrate diet (SCD), Crohn’s disease exclusion diet, autoimmune diet, low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols), Paleolithic diet, Mediterranean diet, and the semi-vegetarian diet, to name a few. Of these, only the SCD and Crohn’s disease exclusion diets have shown improvement in clinical remission and reduction in inflammatory markers.
The SCD diet is based on the theory that malabsorption of disaccharide and polysaccharide carbohydrates leads to bacterial overgrowth and host barrier dysfunction. This diet eliminates grains, dairy, processed meats, and certain vegetables such as potatoes, yams, and legumes. Small uncontrolled studies have shown improvement in symptoms and endoscopy findings. However, this restrictive diet is nearly impossible to follow long term. The Crohn’s disease exclusion diet is a whole foods diet avoiding all processed foods, animal fats, dairy, and gluten. Small studies of this diet have also shown improvement in clinical symptoms and inflammatory markers.
The plethora of studies and reports of the therapeutic effect of diet on IBD provide some promise of the benefit dietary modifications can bring to our IBD patients. However, most dietary studies are underpowered, lack a control arm, and do not include endoscopic endpoints. The current body of evidence remains insufficient to support the use of diet alone for the treatment of IBD. We need randomized clinical controlled trials that are held to the same rigor as those of our approved medical treatments for IBD. Although such trials are challenging, we’ve seen groups rise to the task to carry out more robust dietary studies in the IBD population, and we await the results of several ongoing trials.
IBD is a challenging disease to live with and often leaves our patients feeling out of control. Dietary choices provide an avenue for patients to have some control of their health. However, current evidence does not support the prescription of dietary interventions alone to treat IBD, particularly when we have known, effective therapies. While I am not ready to prescribe diet as a stand-alone treatment for IBD, I make a point to discuss the role diet may play in helping our patients achieve optimal health. As health care providers, it is our responsibility to provide holistic care to our patients, which includes promotion of a healthy diet, absent processed foods and added sugars. Healthy lifestyle choices combined with effective medical and surgical treatments offer our patients the best shot at sustained disease control.
References
1. Hou JK et al. Am J Gastroenterol. 2011;106(4):563-73.
2. Zachos M et al. Cochrane Database Syst Rev. 2007(1):CD000542.
3. Lee D et al. Inflamm Bowel Dis. 2015;21(8):1786-93.
4. Obih C et al. Nutrition. 2016;32(4):418-25.
5. Sigall Boneh R et al. J Crohns Colitis. 2017;11(10):1205-12.
Dr. Raffals is a gastroenterologist in the division of gastroenterology and hepatology, Mayo Clinic, Rochester, Minn. She has no financial conflicts of interest relevant to this paper.
Dear colleagues and friends,
Thank you for your continued interest and support of the Perspectives debates. In this edition, Dr. Ashwin Ananthakrishnan and Dr. Laura Raffals explore the controversial topic of diet-based therapy in inflammatory bowel disease, highlights of the rationales for and against, and the current state of the evidence. All gastroenterologists frequently face questions pertaining to diet and its purported effects on digestive health. I found the discussion relevant to my own general practice, and I hope you will enjoy reading it as much as I did. As always, I welcome your comments and suggestions for future topics at [email protected].
Charles Kahi, MD, MS, AGAF, professor of medicine, Indiana University, Indianapolis. He is also an associate editor for GI & Hepatology News.
IBD can be treated with diet alone
Inflammatory bowel diseases (IBD), comprising Crohn’s disease and ulcerative colitis, have emerged as global diseases. The past 3 decades have seen a rising incidence of these diseases not just in the Western hemisphere, where their prevalence has been well recognized, but also in regions of the world such as Asia and South America where they were previously rare. Whereas several possible factors have been proposed to explain this rising incidence and globalization of disease with varying degrees of supportive evidence, one of the most likely factors is a changing diet. Over the same period that the disease incidence and prevalence have risen, diets worldwide have converged with several common trends observed across countries and continents. These include reductions in dietary fiber, fruits, and vegetables, and increased intake of processed food, animal protein, fats, and sugary drinks, all of which have been linked epidemiologically to Crohn’s disease.
Treatment of Crohn’s disease and ulcerative colitis over the past 2 decades has focused on the immunologic dysfunction observed in these patients. Successful treatment has relied on suppressing immune responses either broadly or through targeted suppression of specific immunologic pathways. By and large, whereas these approaches have enabled us to make significant progress in reducing disease-related morbidity, success has been moderate at best, with fewer than half of patients in any clinical trial achieving remission at the end of a year. Thus, this approach alone may not be sufficient for most patients with IBD.
Treatment of IBD with diet was long considered out of the mainstream and confined to the realm of anecdotes and message boards. Despite most patients believing that diet played a role in development of IBD and onset of flares and that dietary modification was helpful in relieving symptoms, physicians – who for the most part were not trained in these approaches – were not believers, and probably rightly so in the absence of any supporting data.1 However, the parallel emergence of three bodies of literature has now brought diet back into the mainstream of IBD care (such that not a single IBD conference goes by without at least a session or two on diet). First, large prospective cohorts from Europe and North America provided robust evidence linking long-term adult dietary patterns to disease incidence in adult-onset IBD, which supports many important case-control observations made over the past 2 decades.2 Second, and perhaps most important, we began understanding the role of the microbiome in the development of these diseases and recognizing its centrality to bowel inflammation. One of the key determinants of the microbiome is diet, exerting both short-term and long-term influences on the microbial structure. While microbial changes are by no means the only mechanism through which diet can influence intestinal inflammation, they are among the most important, with broad effects across many dietary components. These findings provided a robust scientific basis for investigating the role of diet. Third, while still far from the high-quality (and expensive) set-up of investigational trials of pharmacologic therapies, dietary therapy studies have also evolved to randomized controlled trial designs and investigation of mechanism-driven dietary combinations. Together, I think these three recent advances, in addition to the wealth of existing literature and anecdotal experience, have been important in moving diet (back) into the IBD mainstream.
So what evidence is there that diet is effective in the treatment of IBD? Randomized controlled trials published more than a decade ago demonstrated that exclusive enteral nutrition, wherein all table foods are eliminated from a diet and the patient relies on an elemental diet alone for nutrition, was effective in not just inducing clinical remission but also improving inflammatory biomarkers.3 With results replicated in several trials, exclusive enteral nutrition is, in many parts of the world, one of the first-line treatments for pediatric Crohn’s disease. That this has not been translated to longer-term maintenance therapy is not necessarily an indicator of lack of durable efficacy, but reflects the challenges of maintaining such a restrictive diet long term while living an active, normal life. However, more recent rigorous studies have demonstrated that the effects of exclusive enteral nutrition can be mimicked either by a selected, less-restrictive diet (such as CD-TREAT4), which is more sustainable, or by combining partial enteral nutrition with an elimination diet that is quite diverse (such as CDED5). The latter two are considerably more promising as longer-term dietary treatments for Crohn’s disease with durable efficacy in open-label studies and randomized trials.
What are my final arguments for diet being used as a treatment for IBD? With the exception of very restrictive ones, diets are generally safe. Of course, patients on restricted diets need monitoring for nutritional deficiencies, but this monitoring is likely less intense than that needed for many of our immunosuppressive therapies. Dietary therapies are not associated with an increase in risk of infections or malignancy (unlike our traditional immunosuppressive therapies), and consequently are much more likely to be accepted by our patients than what we are currently offering. In addition, the existing treatments are expensive and consequently difficult to sustain globally with the increasing burden of these diseases. On the other hand, as eating and dietary choices are a routine part of day-to-day life, dietary therapies are not likely to be associated with any excess costs.
Therefore, treating IBD with diet alone is supported by epidemiologic, mechanistic, and clinical evidence and is a safe, effective, and inexpensive alternative for our patients.
References
1. Zallot C et al. Inflamm Bowel Dis. 2013 Jan;19(1):66-72.
2. Sasson AN et al. Clin Gastroenterol Hepatol. 2019 Dec 5;S1542-3565(19)31394-1.
3. Wall CL et al. World J Gastroenterol. 2013;19:7652-60.
4. Svolos V et al. Gastroenterology. 2019;156:1354-67.e6.
5. Levine A et al. Gastroenterology. 2019;157:440-50.e8.
Dr. Ananthakrishnan is a gastroenterologist in the division of gastroenterology, Crohn’s and Colitis Center, Massachusetts General Hospital and Harvard Medical School, Boston. He is supported by funding from the Crohn’s and Colitis Foundation and the Chleck Family Foundation.
IBD can be treated with diet alone – No, it cannot!
The cause of IBD is not completely understood, but we believe something in our environment triggers a dysregulated immune response in individuals with a genetic predisposition to IBD. Among the environmental triggers commonly recognized, diet is considered an important trigger through its ability to affect the composition and health of the gut microbiome and host barrier function. Epidemiologic data support this assumption. Westernization of diet has been associated with the increasing incidence of IBD across the globe and in immigrants who move from developing countries to an industrialized country. Observational studies have shown diets higher in meat and polyunsaturated fatty acids and omega-6 fatty acids are associated with a higher risk for IBD, whereas diets high in fruits, vegetables, and other sources of dietary fiber have a lower risk of IBD.
A growing body of evidence supports the impact food can have on gut health, specifically in mouse IBD models, but it is challenging to translate findings from animal studies into dietary interventions for IBD patients. Mouse studies help us understand the mechanistic basis of how diet may affect IBD, but randomized clinical trials establishing their role in IBD are lacking. This is not surprising as dietary studies are challenging, particularly if done in a robust manner, given the difficulties of ensuring and measuring dietary compliance.
Exclusive enteral nutrition (EEN) has been studied the most rigorously of all diets in IBD and has demonstrated the greatest benefit, compared with other diet studies in IBD. EEN requires the intake of elemental, semi-elemental, or polymeric formulas to meet all nutritional requirements without additional intake of food for 6-8 weeks. Studies have been performed mostly in pediatric populations and have shown effectiveness in induction of remission with reduction in inflammatory markers, including C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin, and even mucosal healing. EEN has not worked out as well for adult populations, because of the poor tolerability of exclusive intake of enteral formulas. Because of this limitation, studies of partial enteral nutrition have been performed that generally allow some food intake in addition to the enteral nutrition. When compared with EEN or anti–tumor necrosis factor–alpha therapy, partial enteral nutrition is a less-effective treatment of Crohn’s disease; however, partial enteral nutrition does appear to improve clinical symptoms.
Beyond EEN, there are many diets that have been considered for the treatment of IBD, including the specific carbohydrate diet (SCD), Crohn’s disease exclusion diet, autoimmune diet, low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols), Paleolithic diet, Mediterranean diet, and the semi-vegetarian diet, to name a few. Of these, only the SCD and Crohn’s disease exclusion diets have shown improvement in clinical remission and reduction in inflammatory markers.
The SCD diet is based on the theory that malabsorption of disaccharide and polysaccharide carbohydrates leads to bacterial overgrowth and host barrier dysfunction. This diet eliminates grains, dairy, processed meats, and certain vegetables such as potatoes, yams, and legumes. Small uncontrolled studies have shown improvement in symptoms and endoscopy findings. However, this restrictive diet is nearly impossible to follow long term. The Crohn’s disease exclusion diet is a whole foods diet avoiding all processed foods, animal fats, dairy, and gluten. Small studies of this diet have also shown improvement in clinical symptoms and inflammatory markers.
The plethora of studies and reports of the therapeutic effect of diet on IBD provide some promise of the benefit dietary modifications can bring to our IBD patients. However, most dietary studies are underpowered, lack a control arm, and do not include endoscopic endpoints. The current body of evidence remains insufficient to support the use of diet alone for the treatment of IBD. We need randomized clinical controlled trials that are held to the same rigor as those of our approved medical treatments for IBD. Although such trials are challenging, we’ve seen groups rise to the task to carry out more robust dietary studies in the IBD population, and we await the results of several ongoing trials.
IBD is a challenging disease to live with and often leaves our patients feeling out of control. Dietary choices provide an avenue for patients to have some control of their health. However, current evidence does not support the prescription of dietary interventions alone to treat IBD, particularly when we have known, effective therapies. While I am not ready to prescribe diet as a stand-alone treatment for IBD, I make a point to discuss the role diet may play in helping our patients achieve optimal health. As health care providers, it is our responsibility to provide holistic care to our patients, which includes promotion of a healthy diet, absent processed foods and added sugars. Healthy lifestyle choices combined with effective medical and surgical treatments offer our patients the best shot at sustained disease control.
References
1. Hou JK et al. Am J Gastroenterol. 2011;106(4):563-73.
2. Zachos M et al. Cochrane Database Syst Rev. 2007(1):CD000542.
3. Lee D et al. Inflamm Bowel Dis. 2015;21(8):1786-93.
4. Obih C et al. Nutrition. 2016;32(4):418-25.
5. Sigall Boneh R et al. J Crohns Colitis. 2017;11(10):1205-12.
Dr. Raffals is a gastroenterologist in the division of gastroenterology and hepatology, Mayo Clinic, Rochester, Minn. She has no financial conflicts of interest relevant to this paper.