In light of the current COVID-19 Pandemic, people are actively looking for dietary ingredients and supplements that support a healthy immune system. Resistant starch supports a healthy immune system, but we do not know how it might impact people with the COVID-19 virus.

Resistant starch’s fermentation in the large intestine helps keep the intestinal barrier intact and working well. It supports all three layers of the gut barrier: the mucus layer, the epithelial cell barrier and the mucosal immune system. See this blog post for further details. However, the immune system within the gut is only part of the body’s immune system. We still have a lot to learn about how this part of the immune system contributes to overall immunity.

This month (April 2020), a meta-analysis of 13 clinical studies with 672 participants (329 in the intervention group and 343 in the control group) concluded that resistant starch significantly reduced interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha), both pro-inflammatory biomarkers produced by the immune system.

According to Dr. Sherry Mansour, an Instructor at Yale University’s Program for Applied Translational Research (NCT04342689), patients suffering from COVID-19 have a significant inflammatory response, including elevated IL-6 levels. Butyrate (the short-chain fatty acid produced by resistant starch in the gut) has also been shown to decrease lung inflammation in animal models through cytokine suppression. Increased butyrate in the intestinal microbiome is also associated with less viral lower respiratory tract infections in allo-HCT recipients.

Dr. Mansour is now working with collaborators at the University of Michigan and the University of Minnesota to test resistant potato starch in patients with the COVID-19 virus. This trial, scheduled to begin on 1 May 2020, will include an estimated 1,300 participants and will be a randomized, quadruple blinded, parallel design with both a resistant starch and placebo groups. All four groups (the participant, care provider, investigator and outcomes assessors) will not know which participants will receive the resistant starch intervention and which will receive the digestible starch control. They will look for changes in the rates of hospitalization, recovery time and the severity of symptoms. The study is scheduled to run through the 1st of October 2020 with analysis of the results and completion of the study in May of 2021. We all look forward to seeing the results of this intervention study next year!

Another new clinical trial of interest is also underway. Metagenics, based in Gig Harbor, Washington, is testing a resistant starch blend in supplement form for its impact on gastrointestinal biomarkers. They are not examining its potential benefits in COVID-19 patients, but have had to change the logistics of their clinical trial due to the virus. Because of the difficulty of conducting in-person studies right now, Metagenics is running this 8-week trial virtually using remote access. Contact trials@metagenics.com or call (253) 853-7233 for additional information. (Participants who complete the study will be compensated.)

Resistant starch has a long history of supporting a healthy metabolism. It is encouraging to see research investigators so quickly examine its potential benefits in light of light of today’s viral and logistical challenges.