Ankylosing spondylitis (AS) is a form of inflammatory arthritis that affects the spine. It is caused by inflammation of the joints between the spine bones (vertebrae). This inflammation can lead to pain and stiffness in the back, neck, and hips, particularly morning stiffness. Severe cases can result in the fusion of vertebrae and leave the spine hunched. In the early stages of AS, individuals usually suffer lower back pain around the sacroiliac joints.
AS typically affects women more than men, and the symptoms of ankylosing spondylitis usually develop in young adulthood. Many people with AS are also affected by bowel diseases, such as inflammatory bowel disease.
Ankylosing spondylitis is a chronic rheumatic disease for which there is currently no cure. However, with appropriate treatment and lifestyle changes, such as dietary interventions, people with AS can lead comfortable and active lives.
What is the Underlying Cause of AS?
The exact cause of ankylosing spondylitis is unknown. However, like other autoimmune diseases, including rheumatoid arthritis, AS is thought to result from a complex interplay between genetic and environmental factors.
Researchers know that AS can run in families, and those with the HLA-B27 gene have an increased risk of developing AS. However, not all individuals who have this gene will go on to develop AS. This is where environmental factors come into play. Environmental triggers for AS may include bacterial infection, vitamin D deficiency, and endocrine and immune system variations.1
Why Are Some AS Patients Advised to Avoid Starch?
Due to some outdated research relating to diet and AS, some AS patients are advised to avoid or reduce the amount of starch they consume. The truth is, there is little justifiable evidence to support this dietary modification. Here we explore how this idea came about and explain why limiting dietary starch can be counterproductive for AS patients.
Ankylosing Spondylitis, a rare type of inflammatory arthritis, is an autoimmune disease that develops when the body’s immune system mistakenly targets normal cells. It is widely believed that certain bacteria can trigger the development of AS. Review analysis has described a link between infection with Klebsiella microorganisms and AS in susceptible individuals.2 Susceptibility appears to be linked to the human leukocyte antigen B27 (HLA-B27) gene, which is expressed by around 88% of AS patients, compared to just 8% of healthy control individuals.3 As HLA-B27 antigens share some similarities in amino acid sequence with Klebsiella antigens,4 molecular mimicry may play a role in the development of AS.
Interestingly, researchers believe that a similar molecular mimicry mechanism may be behind the development of RA and its association with Proteus bacteria.5
Over 40 years ago, researchers proposed that high starch consumption may enrich the growth of Klebsiella bacteria within the gut. In a small individual study, with only 92 participants, the mean number of faecal Klebsiella microbes was found to be higher in individuals on a high carbohydrate/low protein diet compared to those on a low carbohydrate/high protein diet.6
Researchers hypothesised that the increased growth of Klebsiella might increase an individual’s risk of developing AS. The theory being that when susceptible ankylosing spondylitis patients consume starchy foods, Klebsiella species in the gut thrive and grow. As the Klebsiella microorganisms multiply, the immune system responds, ramping up the production of anti-Klebsiella and cross-reactive antibodies, leading to joint inflammation and pain. According to Cowling and colleagues (1980), faecal samples from AS patients contain increased numbers of Klebsiella microbes, which correlates with increased levels of the inflammatory markers, ESR and CRP.7
However, as it turns out, much of the evidence in this area is weak and unsubstantiated. A systematic review of 16 relevant studies explored the association between AS and dietary interventions.8 This review concluded that the evidence in this area is “extremely limited” and unclear. The authors concluded that “there is no evidence that a reduction in starch intake, exclusion of dairy products, consumption of fish and fish oil or probiotic supplementation reduce susceptibility toward AS or diminish AS symptoms”.
One discussed publication was a single-arm intervention study of a low-starch diet on 36 AS patients.9 The review authors highlight a need for clearer data reporting within this study, suggesting that the evidence provided in this, and the other discussed studies, is inconclusive. The authors stress the need for well-designed studies in this area. A clinical trial of 300 patients is currently underway to explore the effects of a low-starch diet on gut bacteria composition.10 The primary outcome measures for this trial will include a change in erythrocyte sedimentation rate and c-reactive protein levels.
Starch is believed to be the primary driver of Klebsiella growth in the colon. But the important question is, is this growth driven by simple sugars derived from processed carbohydrates rather than complex carbohydrates from whole, unprocessed foods?
Are All Starches Equal?
Our extensive research places a question mark on the claim that a high intake of starch can be a driver in the development of AS due to Klebsiella growth. After all, recent research has shown resistant starch to be an important part of a healthy diet, optimising the composition of the gut microbiome and stimulating the cell signalling pathway responsible for anti-inflammatory processes.11
While some evidence suggests that a low starch diet can improve AS symptoms,12 we must consider which sources of starch are important. When we look more closely at the recommended diet for AS patients, the high-starch foods that should be avoided are primarily potato and wheat flour products, many of which are processed. These include pasta, breads, cakes, biscuits, and baked, boiled, or fried potatoes.13 Meanwhile, AS patients are advised to increase their consumption of whole foods, such as fruits and vegetables.8 Notably, researchers have shown that Klebsiella does not grow on plant-derived cellulose but thrives on simple sugars.14
Refined or processed starches are stripped of their natural nutrients and fibre. When kept together, as in whole, unprocessed foods, these components work harmoniously to support a healthy gut. As AS symptoms are closely linked with dysbiosis of the gut microbiota, optimising the gut’s health using a plant-based, whole-foods diet is key. Dietary fibre has been shown to modify the composition of the gut microbiota and increase bacterial diversity, boosting anti-inflammatory bacteria and limiting pro-inflammatory bacteria.15 Anti-inflammatory bacteria break down resistant dietary carbohydrates into beneficial short-chain fatty acids (SCFAs). Notably, SCFAs have been shown to reduce HLA-B27-related inflammation16.
A recently published article showed AS patients to have a significantly lower total antioxidant status and a significantly higher oxidative stress index compared to healthy controls.17 Also, AS patients had a significantly lower dietary phytochemical index (DPI), polyunsaturated fatty acid, n-3 fatty acid, and vitamin C intake. These results suggest that AS patients should focus carefully on their diets, including plenty of phytochemically-rich foods and natural antioxidants.
The Benefits of a Plant-Based Diet
In contrast, plenty of good-quality evidence supports the beneficial effects of a plant-based diet on many chronic diseases. Patients with inflammatory conditions typically thrive on a plant-based diet containing plenty of whole foods that possess anti-inflammatory properties. With inflammatory conditions, such as rheumatic diseases and cardiovascular disease, the right dietary changes can help reduce disease activity and progression.
While there is minimal evidence of the effects of a plant-based diet on AS disease activity, given the similarities between the two diseases, it seems reasonable to extrapolate the extensive evidence for rheumatoid arthritis to ankylosing spondylitis. Multiple meta-analyses have proven the beneficial effects of a plant-based diet on RA symptoms.18,19,20,21
If we consider some real-life scenarios, many people with Ankylosing Spondylitis have dramatically improved their symptoms following the Rheumatoid Solutions plan, which is a Program tailored for inflammatory arthritis patients to optimise their gut health. Check out Selim’s, Skylor’s, Judith’s, Cherie’s, and Tamara’s journeys.
Concluding Remarks
When it comes to optimising the microbiome, the key word is balance. You need a healthy level of good bacteria to reside in the gut to keep the bad bacteria in check. The science supports the key role that a plant-based diet plays in maintaining a healthy and diverse gut microbiome.22
Past reports have led many inflammatory arthritis patients to abandon their healthy anti-inflammatory diet for fear that resistant starches are the enemy. This is simply not true. Rather, resistant starch plays a unique role in regulating the gut microbiota, improving metabolism, reducing inflammation, and supporting a healthy body and overall health. For example, research has shown that potato fibre and potato-resistant starch, present in whole, unprocessed potatoes, increase biomarkers of colonic health, such as enrichment of beneficial bacteria, an increase in cecal and colonic short-chain fatty acids, and improved colonic structure, as indicated by longer intestinal crypts and an increase in the number of goblet cells.23
The superior approach to suppress Klebsiella is to empower your healthy gut bugs, so they can restore balance. For example, your healthy bacterial strains of Bifidobacterium and Lactobacillus may suppress the growth of Klebsiella. Preterm infants orally supplemented with Bifidobacterium and Lactobacillus had lower levels of Klebsiella and other opportunistic microorganisms in the gut.24 Likewise, probiotic supplementation rapidly decreased Klebsiella enrichment that resulted from treatment to eradicate Helicobacter pylori.25 We don’t even need to take probiotic supplements to suppress Klebsiella. Polyphenols, which are abundant in plant foods, can increase Bifidobacterium and Lactobacillus naturally. Thus, we can reduce Klebsiella with what we eat by consuming more whole plants! 26
The outdated research on AS and starch has been misinterpreted for over 40 years. The truth is that processed carbohydrates, stripped of their natural fibre content, should be avoided since they are not only bad for AS patients but also for the general population. These are processed cakes, biscuits, flour, pasta, and other non-whole foods. By contrast, whole plant foods are gut-friendly and rich in fibre which does not stimulate Klebsiella growth. AS patients following a whole-foods plant-based diet have been shown to thrive, as studies show such a diet enriches the microbiome, reduces leaky gut, and reduces inflammation in autoimmune patients, as confirmed by lowered markers of CRP and ESR.
1Zhu, W., He, X., Cheng, K. et al. (2019) Ankylosing spondylitis: etiology, pathogenesis, and treatments. Bone Research 7, 22.
2Ebringer A. (1992). Ankylosing spondylitis is caused by Klebsiella. Evidence from immunogenetic, microbiologic, and serologic studies. Rheumatic Diseases Clinics of North America, 18(1), 105–121.
3Schlosstein, L., Terasaki, P. I., Bluestone, R., & Pearson, C. M. (1973). High association of an HL-A antigen, W27, with ankylosing spondylitis. The New England Journal of Medicine, 288(14), 704–706.
4Schwimmbeck, P. L., & Oldstone, M. B. (1988). Molecular mimicry between human leukocyte antigen B27 and Klebsiella. Consequences for spondyloarthropathies. The American Journal of Medicine, 85(6A), 51–53.
5Ebringer, A., & Rashid, T. (2009). Rheumatoid arthritis is caused by Proteus: the molecular mimicry theory and Karl Popper. Frontiers in Bioscience (Elite Edition), 1(2), 577–586.
6Finegold, S. M., Sutter, V. L., Sugihara, P. T., Elder, H. A., Lehmann, S. M., & Phillips, R. L. (1977). Fecal microbial flora in Seventh Day Adventist populations and control subjects. The American Journal of Clinical Nutrition, 30(11), 1781–1792.
7Cowling, P., Ebringer, R., Cawdell, D., Ishii, M., & Ebringer, A. (1980). C-reactive protein, ESR, and klebsiella in ankylosing spondylitis. Annals of the Rheumatic Diseases, 39(1), 45–49.
8Macfarlane, T. V., Abbood, H. M., Pathan, E., Gordon, K., Hinz, J., & Macfarlane, G. J. (2018). Relationship between diet and ankylosing spondylitis: A systematic review. European Journal of Rheumatology, 5(1), 45–52.
9Ebringer, A., & Wilson, C. (1996). The use of a low starch diet in the treatment of patients suffering from ankylosing spondylitis. Clinical Rheumatology, 15 Suppl 1, 62–66.
10Cardoso, A.M.T. (2020, May – ). Effect of a Low Starch Diet in Patients With Ankylosing Spondylitis. Identifier: NCT04386538. https://clinicaltrials.gov/ct2/show/NCT04386538
11Yang, X., Darko, K. O., Huang, Y., He, C., Yang, H., He, S., Li, J., Li, J., Hocher, B., & Yin, Y. (2017). Resistant Starch Regulates Gut Microbiota: Structure, Biochemistry and Cell Signalling. Cellular Physiology and Biochemistry : International Journal of Experimental Cellular Physiology, Biochemistry, and Pharmacology, 42(1), 306–318.
12Ebringer, A., & Wilson, C. (1996). The use of a low starch diet in the treatment of patients suffering from ankylosing spondylitis. Clinical Rheumatology, 15 Suppl 1, 62–66.
13Rashid, T., Ebringer, A., & Wilson, C. (2013). The role of Klebsiella in Crohn’s disease with a potential for the use of antimicrobial measures. International Journal of Rheumatology, 2013, 610393.
14Deschamps, A. M., Richard, C., & Lebeault, J. M. (1983). Bacteriology and nutrition of environmental strains of Klebsiella pneumoniae involved in wood and bark decay. Annales de Microbiologie, 134A(2), 189–196.
15Simpson, H. L., & Campbell, B. J. (2015). Review article: dietary fibre-microbiota interactions. Alimentary Pharmacology & Therapeutics, 42(2), 158–179.
16Asquith, M., Davin, S., Stauffer, P., Michell, C., Janowitz, C., Lin, P., … & Rosenbaum, J. T. (2017). Intestinal metabolites are profoundly altered in the context of HLA–B27 expression and functionally modulate disease in a rat model of spondyloarthritis. Arthritis & Rheumatology, 69(10), 1984-1995.
17Tel Adıgüzel, K., Yurdakul, F. G., Kürklü, N. S., Yaşar, E., & Bodur, H. (2022). Relationship between diet, oxidative stress, and inflammation in ankylosing spondylitis. Archives of Rheumatology, 37(1), 1–10.
18Khanna, S., Jaiswal, K. S., & Gupta, B. (2017). Managing Rheumatoid Arthritis with Dietary Interventions. Frontiers in Nutrition, 4, 52.
19Alwarith, J., Kahleova, H., Rembert, E., Yonas, W., Dort, S., Calcagno, M., Burgess, N., Crosby, L., & Barnard, N. D. (2019). Nutrition Interventions in Rheumatoid Arthritis: The Potential Use of Plant-Based Diets. A Review. Frontiers in Nutrition, 6, 141.
20Gioia, C., Lucchino, B., Tarsitano, M. G., Iannuccelli, C., & Di Franco, M. (2020). Dietary Habits and Nutrition in Rheumatoid Arthritis: Can Diet Influence Disease Development and Clinical Manifestations?. Nutrients, 12(5), 1456.
21Raad, T., Griffin, A., George, E. S., Larkin, L., Fraser, A., Kennedy, N., & Tierney, A. C. (2021). Dietary Interventions with or without Omega-3 Supplementation for the Management of Rheumatoid Arthritis: A Systematic Review. Nutrients, 13(10),
22Tomova, A., Bukovsky, I., Rembert, E., Yonas, W., Alwarith, J., Barnard, N. D., & Kahleova, H. (2019). The Effects of Vegetarian and Vegan Diets on Gut Microbiota. Frontiers in Nutrition, 6, 47.
23Paturi, G., Nyanhanda, T., Butts, C. A., Herath, T. D., Monro, J. A., & Ansell, J. (2012). Effects of potato fiber and potato-resistant starch on biomarkers of colonic health in rats fed diets containing red meat. Journal of Food Science, 77(10), H216–H223.
24Alcon-Giner, C., Dalby, M. J., Caim, S., Ketskemety, J., Shaw, A., Sim, K., Lawson, M. A. E., Kiu, R., Leclaire, C., Chalklen, L., Kujawska, M., Mitra, S., Fardus-Reid, F., Belteki, G., McColl, K., Swann, J. R., Kroll, J. S., Clarke, P., & Hall, L. J. (2020). Microbiota Supplementation with Bifidobacterium and Lactobacillus Modifies the Preterm Infant Gut Microbiota and Metabolome: An Observational Study. Cell reports. Medicine, 1(5), 100077.
25Tang, B., Tang, L., Huang, C., Tian, C., Chen, L., He, Z., Yang, G., Zuo, L., Zhao, G., Liu, E., Wang, S., Lin, H., He, J., & Yang, S. (2021). The Effect of Probiotics Supplementation on Gut Microbiota After Helicobacter pylori Eradication: A Multicenter Randomized Controlled Trial. Infectious Diseases and Therapy, 10(1), 317–333.
26Tomova, A., Bukovsky, I., Rembert, E., Yonas, W., Alwarith, J., Barnard, N. D., & Kahleova, H. (2019). The Effects of Vegetarian and Vegan Diets on Gut Microbiota. Frontiers in Nutrition, 6, 47.
