gut bacteria

The Specific Carbohydrate Diet (SCD) for IBD: Everything You Need to Know

Alyssa Luck · Mar 14, 2022 · Leave a Comment

Summary: The Specific Carbohydrate Diet is an increasingly popular dietary intervention for IBD patients that involves limiting dietary carbohydrate to monosaccharides, or simple sugars. In practical terms, this involves eliminating all sources of starch, as well as sugar (sucrose) and lactose. It has anecdotally been extremely helpful for a variety of digestive issues, and some published clinical research is beginning to accumulate suggesting benefit for IBD patients, although the best-designed trial thus far does not demonstrate any benefit over a “Mediterranean” diet. Further, the scientific theory underlying the SCD principles does not stand up to our current understanding of the role of intestinal bacteria in IBD, and more importantly, does not support the “fanatical adherence” called for. Ultimately, the diet has helped a great number of IBD sufferers and may be right for some people, but there are likely other dietary and lifestyle approaches that could deliver similar or greater benefit with less restrictiveness and easier-to-follow guidelines.

This article is part of the IBD Index. Last updated on March 14, 2022.

This article aims to give a high-level overview of the Specific Carbohydrate Diet, as well as practical guidance. For a deep (deep, deep) dive into the science, check out The Science Behind the Specific Carbohydrate Diet (SCD): Brilliant or Bunk?.

Ah, the Specific Carbohydrate Diet. I’ll save my experience with it for another time and keep this page as objective as possible, but as a disclaimer: this is the diet I stuck to religiously for the vast majority of the ~3 years between being diagnosed with UC in 2008 and having my colon removed in 2011. (So at the very least, I’m writing from a place of experience!)

From the looks of it, the diet has only grown in popularity since that time. Even giant online health websites like WebMD, VeryWellFit, and Healthline are chiming in about it. (You don’t need to go read those pages. Just keep reading this one; it’s better.)

This post will give you an overview of the SCD, where it came from, the rationale behind it, pros/cons, and things to watch out for. I also link some relevant resources, and at the bottom of the post (as usual) you’ll find a literature review of sorts. An annotated bibliography, if you will.

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The Science Behind the Specific Carbohydrate Diet (SCD): Brilliant or Bunk?

Alyssa Luck · Mar 14, 2022 · Leave a Comment

Summary: In her 1987 book Breaking the Vicious Cycle, Elaine Gotschall proposed the hypothesis that digestive diseases – including IBD – are perpetuated by a vicious cycle of carbohydrate malabsorption, bacterial overgrowth, and intestinal injury, and can therefore be resolved by removing specific carbohydrates from the diet to break the cycle. Much of her research was quite prescient, but key claims fail to stand up to scrutiny, and the science does not support adherence to SCD principles. A modern look at Gottschall’s hypotheses reveal that modulating the intestinal bacteria through diet is indeed as important as she suspected, but that strategies other than the SCD are better able to accomplish that goal.

This article is part of the IBD Index. Last updated April 20, 2022.

This article is a deep dive into the science behind the Specific Carbohydrate Diet, and is a companion post to the high-level summary post: The Specific Carbohydrate Diet (SCD) for IBD: Everything You Need to Know.

The Specific Carbohydrate Diet as laid out in the 1987 book Breaking the Vicious Cycle (BTVC) by Elaine Gotschall is respectably science-driven. She lists dozens of references in the back of the book to support her recommendations (which is impressive considering she was conducting this research in the pre-internet era), and the book itself has been cited in the literature over 100 times. The SCD is also increasingly showing up as an intervention in clinical research, first in case studies and more recently in a large randomized controlled trial.

I said this in my main post on the SCD, but in many ways, Gottschall was truly ahead of her time with the theories she lays out in her book, although of course she leaned heavily on the work of Dr. Haas. In researching this post, I was struck by how relevant her work still is, and how many modern lines of inquiry flow naturally from her hypotheses.

That said, the big wheel of science keeps on turning, and there’s much to be critiqued in BTVC, with quite a few issues that are – in my view, at least – highly relevant to patients. When you have a dietary protocol with rules that are as specific as those of the SCD – and when the diet originator claims they must be followed with “fanatical adherence” – you gotta make sure they stand up to scrutiny, right?

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Is the Low-FODMAP Diet Effective for IBD?

Alyssa Luck · Mar 14, 2022 · Leave a Comment

Summary: A low-FODMAP diet, which is a common intervention for IBS, is being increasingly studied in IBD patients. Unfortunately, the diet does not currently show efficacy for reducing inflammation, but has been shown in clinical trials to be effective at managing functional gastrointestinal symptoms in patients whose disease is in remission. Although a common concern with low-FODMAP diets is potential adverse effects on the microbiome from removing fermentable substrates, its actual effects on the microbiome in practice have not yet been clearly characterized, with inconsistent results across studies. For those who wish to support their microbiome on a low-FODMAP diet, resistant starch and Sunfiber are good low-FODMAP prebiotic options.

This article is part of the IBD Index. Last updated on April 20, 2022.

The low-FODMAP diet is somewhat unique among IBD interventions because it promises to intervene in the common but oft-overlooked situation of continuing functional gastrointestinal symptoms even in the absence of inflammation.

I cover the basics and practical aspects of a low-FODMAP diet in The Low-FODMAP Diet for IBD: Everything You Need to Know. In this article, I take a deep dive into all the evidence regarding the effectiveness of a low-FODMAP diet for IBD, both from the perspective of reducing inflammation and managing symptoms. I also address the most common concern about a low-FODMAP diet: its effects on the microbiome.

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The Low-FODMAP Diet for IBD: Everything You Need to Know

Alyssa Luck · Mar 14, 2022 · Leave a Comment

Summary: The low-FODMAP diet originated in 2005 out of a hypothesis about IBD pathogenesis, but quickly became a go-to treatment for IBS. For IBD, the diet has found its niche as an intervention for addressing lingering functional gastrointestinal symptoms in patients whose IBD is in remission. For this purpose, the diet has demonstrated successful symptom reduction in clinical trials, but no evidence yet indicates that it is helpful for quelling inflammation. The biggest risk associated with a low-FODMAP diet is adverse effects on the microbiome from depriving it of fermentable carbohydrates, but this can be addressed by including low-FODMAP prebiotics (such as Sunfiber and resistant starch) and by reintroducing FODMAP-containing foods as tolerated.

This article is part of the IBD Index. Last updated on April 20, 2022.

This article aims to give a high-level overview of the low-FODMAP diet, as well as practical guidance. For a deeper dive into the science, you can check out my article Is the Low-FODMAP Diet Effective for IBD?.

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Small Intestinal Bacterial Overgrowth (SIBO) and IBD

Alyssa Luck · Mar 14, 2022 · Leave a Comment

This article is part of the IBD Index. Last updated on March 14, 2022.

Small intestinal bacterial overgrowth, or SIBO, is one area of research in the field of intestinal health that has gone from relative obscurity to almost totally mainstream just in the past decade. As research has progressed, the name “overgrowth” has become a bit of a misnomer, with recent evidence indicating that the issue isn’t bacterial overgrowth per se, but rather bacterial dysbiosis in the small intestine.

In any case, SIBO is often identified in patients with IBD*, and can both affect and be affected by other IBD-related disease processes. Therefore, the question of whether and how to treat it is highly relevant. While treatment of SIBO is certainly a lever one can pull that may affect symptoms and overall disease state, SIBO is also often a symptom of other dysfuctions and environmental factors, such that addressing those other factors could resolve the SIBO without explicit treatment. And because testing for and treating SIBO is often quite complicated, it’s best to take it in context and consider whether there are other “no-brainer” levers that could be pulled first.

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Akkermansia Muciniphila: Bane or Boon for IBD?

Alyssa Luck · Mar 21, 2021 · Leave a Comment

Summary: Akkermansia muciniphila is a commensal bacteria found in healthy human colons that is widely regarded as a promising next-generation probiotic. Researchers have mainly focused on therapeutic potential for obesity and diabetes, but there’s also substantial interest in the field of IBD, particularly for its beneficial effects on gut barrier function. However, a minority of researchers have suggested that Akkermansia muciniphila could worsen colitis. Despite that, most of the evidence thus far suggests that A. muciniphila could potentially be leveraged as a beneficial therapy for IBD and gut health in general once more research has been done.

This post is part of the IBD Index.

Lactobacillus and Bifidobacteria species may still be the darlings of the probiotic world, but there’s a new kid on the block: Akkermansia muciniphila.

This bacteria was isolated for the first time in 2004 (1) so it’s still relatively new to the game, but you can see from this fun trend analysis (2) that research has exploded, especially in the last couple years.

Source: Hojat et al., Global scientific output trend for *Akkermansia muciniphila* research: a bibliometric and scientometric analysis, 2020

So what is Akkermansia muciniphila, and why the interest all of a sudden?

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