This article is part of the IBD Index. Last updated April 22, 2022.
“Semi-vegetarian diet? What a dumb and nonspecific name, Alyssa. Are you going to write an article about a “semi-carnivore” diet too? Ever heard the word omnivore?”
Yeah, I know. But believe it or not, the “semi-vegetarian diet” is a diet with fairly specific parameters that is used to treat IBD in Japan.
Table of Contents
What is a semi-vegetarian/plant-based diet?
Is there evidence to support a semi-vegetarian/plant-based diet for IBD?
Why is treatment of IBD so much better in Japan?
Review of the literature
What is a Semi-Vegetarian/Plant-Based Diet?
This paper gives a great overview of the diet in the “History and concept of PBD in IBD” section, but to summarize here, Nakadori General Hospital in Japan has been providing a semi-vegetarian diet to ulcerative colitis patients since 2003. It appeared in the literature for the first time in a 2005 case report, and was fleshed out in more detail in a 2010 paper. (Of note, the researchers transitioned to using the term “plant-based diet” (PBD) rather than “semi-vegetarian diet” (SVD) for their more recent publications, but the diet is the same, and is depicted in the food pyramid below.)
Is There Evidence to Support a Semi-Vegetarian/Plant-Based Diet for IBD?
Yes! The research group led by Mitsuro Chiba in Japan, first at Nakadori General Hospital and later at Akita City Hospital, has published several papers detailing the success of SVD/PBD in treating IBD.
This group has achieved remarkable results with Crohn’s patients: using a combination of infliximab (Remicade) and SVD/PBD, they’ve achieved a remission rate of 96% in 46 consecutive cases. (Source)
Note that these are not randomized controlled trials, and therefore the quality of the evidence would be considered low. But as far as I’m concerned, that is to their credit; it’s obvious that their priority is helping patients heal rather than producing “good” science. And when the intervention is as low-risk and holistic as this (ie a nutritionally complete and balanced diet), I think that approach is perfectly valid.
Why is Treatment of IBD So Much Better in Japan?
Glad you asked, I’ve been wondering the same thing.
All kidding aside, there’s a stark difference in how IBD treatment is discussed and implemented in these papers compared with the standard of care I’m familiar with in the US. Below are a few quotes I found particularly noteworthy.
In our practice, hospitalization plays a critical role in replacement of an omnivorous diet with PBD. It is obvious that the majority of diseases we face are chronic diseases (lifestyle diseases) due to an unhealthy lifestyle. Therefore, incorporation of a healthy lifestyle in medicine, namely lifestyle medicine, is fundamental for prevention and treatment of chronic diseases. Changes in lifestyle including dietary habits are not easy. Hospitalization helps limit risk factors for IBD and our health such as smoking, alcohol, sweets, and animal foods, while patients benefit from preventive factors every day such as intake of vegetables and fruits. Hospitalization seemed to enhance their self-management skills, which contributed greatly to prevention of relapse.Chiba et al. Recommendation of plant-based diets for inflammatory bowel disease. 2019. Transl Pediatr.
Although medication is needed in the active phase of IBD, diet is generally more important than medication to maintain remission in the quiescent phase. If a suitable diet is established as part of a changing lifestyle, medication ultimately may not be needed to maintain remission.Chiba et al. Relapse Prevention in Ulcerative Colitis by Plant-Based Diet Through Educational Hospitalization: A Single-Group Trial. (2018). Perm J.
It is suggested that patients can stop medication when they feel confident after a few years of remission using the PBD. This may go some way to relieving a patient’s fear about the disease, especially compared with being told that they may need to receive medication for life.Chiba et al. Relapse Prevention in Ulcerative Colitis by Plant-Based Diet Through Educational Hospitalization: A Single-Group Trial. (2018). Perm J.
Review of the Literature
Note: These are in an order that makes sense from the standpoint of information conveyance; not in chronological or alphabetical order.
Chiba et al. Recommendation of plant-based diets for inflammatory bowel disease. 2019. Transl Pediatr.
- This is a good introduction to and review of the SVD/PBD that this research group has used in their hospital to treat IBD patients since 2003, providing background and rationale for diet design, etc.
- As of the writing of this paper, the research group has treated more than 159 UC patients and 70 CD patients with the SVD/PBD.
Chiba et al. Lifestyle-related disease in Crohn’s disease: Relapse prevention by a semi-vegetarian diet. 2010. World J Gastroenterol.
- This paper details the composition and nutrient breakdown of the semi-vegetarian diet (SVD) used at the hospital, including meal pictures and food pyramid.
- Based on a 2-year analysis of Crohn’s disease relapse rates, a SVD was highly effective in preventing relapse.
- Note: All 22 patients were advised to continue a SVD, so the two groups compared were those who chose to continue vs. those who did not. I probably don’t have to tell you that this leaves lots of room for confounding variables, since essentially you’re comparing a group that follows their doctor’s advice to a group that doesn’t.
- 17 patients with severe UC were treated with infliximab (Remicade) and SVD/PBD
- 13/17 (76%) achieved remission during the induction phase, and one patient had to undergo colectomy; these rates are better than those seen with conventional treatment
- Cumulative relapse rate at one year was 25% with no additional colectomy cases
Chiba et al. Relapse Prevention in Ulcerative Colitis by Plant-Based Diet Through Educational Hospitalization: A Single-Group Trial. (2018). Perm J.
- Patients included in the study included both initial cases and relapses who did not need immediate treatment
- Patients were hospitalized and fed SVD/PBD for two weeks; they were also educated about the disease and lifestyle factors to consider when taking care of themselves moving forward
- 77% of patients experienced improvements in symptoms and/or laboratory values during the hospitalization
- Overall relapse rates were far lower than typical relapse rates with conventional therapy: cumulative relapse rates at 1, 2, 3, 4, and 5 years of follow-up were 2%, 4%, 7%, 19%, and 19%, respectively
Chiba et al. Relapse Prevention by Plant-Based Diet Incorporated into Induction Therapy for Ulcerative Colitis: A Single-Group Trial. (2019). Perm J.
- As opposed to the previous study, which only included patients who didn’t need immediate treatment and received educational hospitalization only, this study looked at relapse prevention among typical UC patients when SVD/PBD was used as part of induction therapy
- 92 cases were included in the analysis, and the overall cumulative relapse rates at 1, 2, 3, 4, and 5 years of follow-up were 24%, 30%, 36%, 37%, and 39%, respectively, which are lower than those reported with conventional therapy
Chiba et al. Onset of Ulcerative Colitis in the Second Trimester after Emesis Gravidarum: Treatment with Plant-based Diet. (2018). Inflamm Bowel Dis.
- Comment/letter to the editor re: a case of a 36-year-old woman who developed UC in her second trimester. She was admitted to the hospital, fed a SVD/PBD for 10 days (no medication), then discharged with a negative stool occult blood test
- Case study of a man who developed UC while following a low-carb weight loss diet (note that as discussed in the IBD Index article about ketogenic diets, I question to what extent this man’s diet could’ve possibly been “low-carb”)
- Was hospitalized and fed SVD/PBD for 11 days, then discharged with a negative stool occult blood test
- Interestingly, the patient had heard that this particular style of plant-based diet was effective for treating UC, so he started his own version after being diagnosed. According to the plant-based scoring system, his original low-carb diet had a score of −13; his attempt at a semivegetarian diet had a score of 18; and the hospital’s semivegetarian diet (which put him into remission) had a score of 35
- Of note, he had reverted to a diet with a lower plant-based score (2) at 10 months post-discharge, and once again had UC symptoms
A couple selected Crohn’s Disease studies
Chiba et al. Lifestyle-related disease in Crohn’s disease: relapse prevention by a semi-vegetarian diet. 2010. World J Gastroenterol.
- First study in Japan on SVD in CD showing 100% remission at 1 year and 92% remission at 2 years. Prevention in time to relapse in SVD to omnivores was p=0.0003.