Flavonoids aren’t a widely discussed topic in the IBD community nor in the doctor’s office yet emerging research has discovered these substances to be powerful in regulating inflammation observed in IBD. One exciting area in nutrition research today is the study of bioactive food components that not only decrease risk of disease and but play a compelling role in disease mitigation due to their antiinflammatory nature. Polyphenols are compounds found in plants hypothesized to have antioxidant potential due to their chemical structure. Flavonoids, one of the most common groups of polyphenols found in the human diet, look to have especially interesting benefits for people with IBD. In so many programs and dietary frameworks pushed on IBDers the perspective revolves around what foods to disclude from one’s diet, however in our approach to IBD we focus on helping clients develop their own custom dietary framework with a focus which foods to actually include. These are foods that promote healing. The incredible super foods that contain flavonoids are a spectacular example of this. 

What are Flavonoids?

Part of an emerging area of nutrition research, flavonoids are one of the latest bioactive compounds in plants linked to regulating the inflammation associated with IBD. Polyphenols such as flavonoids, due to their antioxidant and anti-inflammatory nature, are shown not only to decrease risk of diseases like IBD, but also to mitigate these diseases when already in progress. Lucky for us, flavonoids are easy to incorporate into the diet: they are present in most plant-based foods, with especially high proportions in colorful foods such as berries, tea, broccoli, and even dark chocolate! They are also the main bioactive component in some of the herbs we talk about here at IBDCoach including licorice, ginger, and ginseng.

In nature, flavonoids are responsible for color and aroma, but they also serve an important role in plants’ self-defense against microbes, UV, and extreme climates like drought and frost. These compounds also impart protective properties to us humans when ingested and consumed by our colonic microbiota. These properties translate to  immunomodulatory, anti-inflammatory, antioxidant, and prebiotic benefits that can further impact our microflora balance and intestinal integrity, all of which are important factors in IBD. In this article, we will look closely at a few of the well-studied types of flavonoids (Figure 1) and what the research can mean for you and your gut health. 

Figure 1: Flavonoid Types and Food Sources.

Flavonoids as Prebiotics for Gut Microbiota

It’s estimated that 90% of total dietary intake of polyphenols like flavonoids bypasses both digestion and absorption in the small intestine and are instead metabolized by our colonic microbiota. Acting as a prebiotic, flavonoids feed our healthy gut microflora and set off a chain reaction of secondary bioactive metabolites that support other healthy gut microbes, all of which can benefit dysbiosis-related diseases like IBD where microbiota populations are out of balance.  In one animal study modeling colitis, the flavonoid compound resveratrol resulted in an increase in the beneficial bacteria Bifidobacterim and Lactobacillus while reducing enterobacteria (a bacteria known to cause intestinal upset). (1) Catechins, a sub-category of flavonoids, stabilize the gastrointestinal tract environment by promoting proliferation of beneficial intestinal bacteria, regulating the intestinal flora, and potentially regulating tight junctions in the gut epithelium. (2) Curcurmin improved intestinal integreity and butyrate production by microbes in an animal study modeling IBD.(13)  As for human trials, curcumin was also indicated prolong remission in UC patients with quiescent UC.(2,3) These studies suggest that through means of our microbiota, flavonoids may be powerful in the management ofIBD.

Evidence Links Different Types of Flavonoids and IBD Biomarkers

Both in vitro and animal studies report dietary flavonoids’ ability to influence the activity of inflammatory mediators. Indonesian pomegranate peel, rich in anthocyanins and other polyphenols, both attenuated the expression of proinflammatory cytokines (such as TNF-ɑ and IL-IB) involved in the inflammatory response, and also enhanced the butyrate producing bacteria Ruminococcacae in an animal model of UC.(4,5)  In murine models,  the natural flavone chrysin has demonstrated inhibitory effects on inflammatory mediators and ameliorative effects on the disrupted colonic architecture.(6) Furthermore, flavonoids like quercetin, rutoside, morin, and hesperidin all alleviate diarrhea symptoms seen in experimental IBD by improving intestinal barrier function.(7-10)

While more research has been performed in mice than in humans, these limited human studies show promising results. One clinical trial using pomegranate (Punica granatum) peel extract demonstrated a decrease in patients’ IBD symptoms (incontinence of feces, general well-being, need of antidiarrheal) after four weeks compared to a placebo group.(11) Another trial treated thirteen UC patients with an anthocyanin-rich bilberry mixture, and after 6 weeks of intervention, subjects saw  significant reduction in mucosal inflammation and fecal calprotectin. While meaningful, those improvements were partially reversed by a followup report 4 weeks after the completion of the interventions, which suggests therapeutic effects of some flavonoid treatments may be transient.(12)

Takeaways

Here at IBDCoach, we strive to uncover and present to you the latest research on IBD foods and therapeutics so you can be informed to incorporate them into your everyday practices and achieve remission. When it comes to flavonoids, the evidence is clear: flavonoids can alter our immune responses, improve our intestinal barrier, and reshape our microbiota. These compounds are abundant in foods, from the purple-producing anthocyanins in blueberries, blackberries, and red cabbage, to the catechins found in green tea, cacao (dark chocolate), apples, legumes, and even some nuts like almonds and pistachios. These foods can be consumed in whole form or in powders and extracts depending on what your current IBD state can tolerate. And when combined with other interventions, a flavonoid-rich diet that includes foods in can mitigate symptom exacerbation in the midst of a flare and even help prevent flares in the first place. We hope next time you’re planning meals, you take a moment to add some flavonoid-rich foods to your grocery list!

References 

  1. Larrosa, M. et al. Effect of a low dose of dietary resveratrol on colon microbiota, inflammation and tissue damage in a DSS-induced colitis rat model. J. Agric. Food Chem. 57, 2211–2220 (2009).
  2. Fan, F.-Y., Sang, L.-X. & Jiang, M. Catechins and Their Therapeutic Benefits to Inflammatory Bowel Disease. Mol. J. Synth. Chem. Nat. Prod. Chem. 22, (2017).
  3. Curcumin Maintenance Therapy for Ulcerative Colitis: Randomized, Multicenter, Double-Blind, Placebo-Controlled Trial – Clinical Gastroenterology and Hepatology. https://www.cghjournal.org/article/S1542-3565(06)00800-7/fulltext.
  4. H, K. et al. Pomegranate polyphenolics reduce inflammation and ulceration in intestinal colitis-involvement of the miR-145/p70S6K1/HIF1α axis in vivo and in vitro. J. Nutr. Biochem. 43, 107–115 (2017).
  5. Kusmardi, K., Hermanto, D., Estuningytas, A., Tedjo, A. & Priosoeryanto, B. P. The Potency of Indonesia’s Pomegranate Peel Ethanol Extract (Punica Granatum Linn.) As Anti-inflammatory Agent in Mice Colon Induced by Dextran Sodium Sulfate: Focus on Cyclooxygenase-2 and Inos Expressions  Asian J. Pharm. Clin. Res. 370–375 (2017) doi:10.22159/ajpcr.2017.v10i12.21390.
  6. Shin, E. K., Kwon, H.-S., Kim, Y. H., Shin, H.-K. & Kim, J.-K. Chrysin, a natural flavone, improves murine inflammatory bowel diseases. Biochem. Biophys. Res. Commun. 381, 502–507 (2009).
  7. Crespo, M. E., Gálvez, J., Cruz, T., Ocete, M. A. & Zarzuelo, A. Anti-inflammatory activity of diosmin and hesperidin in rat colitis induced by TNBS. Planta Med. 65, 651–653 (1999).
  8. Sánchez de Medina, F., Gálvez, J., Romero, J. A. & Zarzuelo, A. Effect of quercitrin on acute and chronic experimental colitis in the rat. J. Pharmacol. Exp. Ther. 278, 771–779 (1996).
  9. Gálvez, J. et al. Rutoside as mucosal protective in acetic acid-induced rat colitis. Planta Med. 63, 409–414 (1997).
  10. Ocete, M. A. et al. Effects of morin on an experimental model of acute colitis in rats. Pharmacology 57, 261–270 (1998).
  11. Kamali, M. et al. Efficacy of the Punica granatum peels aqueous extract for symptom management in ulcerative colitis patients. A randomized, placebo-controlled, clinical trial. Complement. Ther. Clin. Pract. 21, 141–146 (2015).
  12. Biedermann, L. et al. Bilberry ingestion improves disease activity in mild to moderate ulcerative colitis – an open pilot study. J. Crohns Colitis 7, 271–279 (2013).
  13. Ohno, M. et al. Nanoparticle curcumin ameliorates experimental colitis via modulation of gut microbiota and induction of regulatory T cells. PloS One 12, e0185999 (2017).

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