Abstract
Fibers remain undigested until they reach the colon, where some are fermented by gut microbiota, producing metabolites called short-chain fatty acids (SCFAs), such as acetate and butyrate1. SCFAs lower blood pressure in experimental models2,3,4,5, but their translational potential is unknown. Here we present the results of a phase II, randomized, placebo-controlled, double-blind cross-over trial (Australian New Zealand Clinical Trials Registry ACTRN12619000916145) using prebiotic acetylated and butyrylated high-amylose maize starch (HAMSAB) supplementation6. Twenty treatment-naive participants with hypertension were randomized to 40 g per day of HAMSAB or placebo, completing each arm for 3 weeks, with a 3-week washout period between them. The primary endpoint was a reduction in ambulatory systolic blood pressure. Secondary endpoints included changes to circulating cytokines, immune markers and gut microbiome modulation. Patients receiving the HAMSAB treatment showed a clinically relevant reduction in 24-hour systolic blood pressure independent of age, sex and body mass index without any adverse effects. HAMSAB increased levels of acetate and butyrate, shifted the microbial ecosystem and expanded the prevalence of SCFA producers. In summary, a prebiotic intervention with HAMSAB could represent a promising option to deliver SCFAs and lower blood pressure in patients with essential hypertension.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 12 digital issues and online access to articles
$119.00 per year
only $9.92 per issue
Buy this article
- Purchase on SpringerLink
- Instant access to the full article PDF.
USD 39.95
Prices may be subject to local taxes which are calculated during checkout



Similar content being viewed by others
Data availability
The microbiome data described in this article are available at the GenBank Nucleotide Database (BioProject ID PRJNA903679). We did not obtain patient consent for all the data to be available publicly. However, the data underlying this article can be shared for selected research questions upon reasonable request to the corresponding author. Please email F.Z.M. at francine.marques@monash.edu, who will respond within 4 weeks.
Code availability
The microbiome coding used is described at https://github.com/michael-nakai/waterway.
References
Maslowski, K. M. & Mackay, C. R. Diet, gut microbiota and immune responses. Nat. Immunol. 12, 5–9 (2011).
Marques, F. Z. et al. High-Fiber diet and acetate supplementation change the gut microbiota and prevent the development of hypertension and heart failure in hypertensive mice. Circulation 135, 964–977 (2017).
Bartolomaeus, H. et al. The short-chain fatty acid propionate protects from hypertensive cardiovascular damage. Circulation 139, 1407–1421 (2019).
Kim, S. et al. Imbalance of gut microbiome and intestinal epithelial barrier dysfunction in patients with high blood pressure. Clin. Sci. (Lond.) 132, 701–718 (2018).
Kaye, D. M. et al. Deficiency of prebiotic fibre and insufficient signalling through gut metabolite sensing receptors leads to cardiovascular disease. Circulation 141, 1393–1403 (2020).
Rhys-Jones, D. et al. Microbial interventions to control and reduce blood pressure in Australia (MICRoBIA): rationale and design of a double-blinded randomised cross-over placebo controlled trial. Trials 22, 496 (2021).
Collaborators, G. B. D. R. F. Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019. Lancet 396, 1223–1249 (2020).
Collaboration, N. C. D. R. F. Worldwide trends in hypertension prevalence and progress in treatment and control from 1990 to 2019: a pooled analysis of 1201 population-representative studies with 104 million participants. Lancet 398, 957–980 (2021).
Beaney, T. et al. May Measurement Month 2019: the Global Blood Pressure Screening Campaign of the International Society of Hypertension. Hypertension 76, 333–341 (2020).
Benjamin, E. J. et al. Heart disease and stroke statistics—2019 update: a report from the American Heart Association. Circulation 139, e56–e528 (2019).
Appel, L. J. et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N. Engl. J. Med. 336, 1117–1124 (1997).
Reynolds, A. et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet 393, 434–445 (2019).
Marques, F. Z., Mackay, C. R. & Kaye, D. M. Beyond gut feelings: how the gut microbiota regulates blood pressure. Nat. Rev. Cardiol. 15, 20–32 (2018).
Muralitharan, R. R. et al. Microbial peer pressure: the role of the gut microbiota in hypertension and its complications. Hypertension 76, 1674–1687 (2020).
Gill, S. K., Rossi, M., Bajka, B. & Whelan, K. Dietary fibre in gastrointestinal health and disease. Nat. Rev. Gastroenterol. Hepatol. 18, 101–116 (2021).
Gill, P. A., van Zelm, M. C., Muir, J. G. & Gibson, P. R. Review article: short chain fatty acids as potential therapeutic agents in human gastrointestinal and inflammatory disorders. Aliment Pharmacol. Ther. 48, 15–34 (2018).
Tilves, C. et al. Increases in circulating and fecal butyrate are associated with reduced blood pressure and hypertension: results From the SPIRIT trial. J. Am. Heart Assoc. 11, e024763 (2022).
Gill, P. A., Bogatyrev, A., van Zelm, M. C., Gibson, P. R. & Muir, J. G. Delivery of acetate to the peripheral blood after consumption of foods high in short-chain fatty acids. Mol. Nutr. Food Res. 65, e2000953 (2021).
Clarke, J. M., Bird, A. R., Topping, D. L. & Cobiac, L. Excretion of starch and esterified short-chain fatty acids by ileostomy subjects after the ingestion of acylated starches. Am. J. Clin. Nutr. 86, 1146–1151 (2007).
Marino, E. et al. Gut microbial metabolites limit the frequency of autoimmune T cells and protect against type 1 diabetes. Nat. Immunol. 18, 552–562 (2017).
Norlander, A. E., Madhur, M. S. & Harrison, D. G. The immunology of hypertension. J. Exp. Med. 215, 21–33 (2018).
Heran, B. S., Wong, M. M., Heran, I. K. & Wright, J. M. Blood pressure lowering efficacy of angiotensin converting enzyme (ACE) inhibitors for primary hypertension. Cochrane Database Syst. Rev. CD003823 (2008).
Stamler, J. et al. INTERSALT study findings. Public health and medical care implications. Hypertension 14, 570–577 (1989).
Calderon-Perez, L. et al. Gut metagenomic and short chain fatty acids signature in hypertension: a cross-sectional study. Sci. Rep. 10, 6436 (2020).
Nakai, M. et al. Essential hypertension is associated with changes in gut microbial metabolic pathways: a multisite analysis of ambulatory blood pressure. Hypertension 78, 804–815 (2021).
Vacca, M. et al. The controversial role of human gut lachnospiraceae. Microorganisms 8, 573 (2020).
Toya, T. et al. Coronary artery disease is associated with an altered gut microbiome composition. PLoS ONE 15, e0227147 (2020).
Beale, A. L. et al. The gut microbiome of heart failure with preserved ejection fraction. J. Am. Heart Assoc. 10, e020654 (2021).
Ezeji, J. C. et al. Parabacteroides distasonis: intriguing aerotolerant gut anaerobe with emerging antimicrobial resistance and pathogenic and probiotic roles in human health. Gut Microbes 13, 1922241 (2021).
Falony, G. et al. Population-level analysis of gut microbiome variation. Science 352, 560–564 (2016).
Lei, Y. et al. Parabacteroides produces acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration. Microbiome 9, 115 (2021).
Gill, P. A., Muir, J. G., Gibson, P. R. & van Zelm, M. C. A randomized dietary intervention to increase colonic and peripheral blood short-chain fatty acids modulates the blood B- and T-cell compartments in healthy humans. Am. J. Clin. Nutr. 116, 1354–1367 (2022).
Nutting, C. W., Islam, S. & Daugirdas, J. T. Vasorelaxant effects of short chain fatty acid salts in rat caudal artery. Am. J. Physiol. 261, H561–H567 (1991).
Mortensen, F. V., Nielsen, H., Mulvany, M. J. & Hessov, I. Short chain fatty acids dilate isolated human colonic resistance arteries. Gut 31, 1391–1394 (1990).
Annison, G., Illman, R. J. & Topping, D. L. Acetylated, propionylated or butyrylated starches raise large bowel short-chain fatty acids preferentially when fed to rats. J. Nutr. 133, 3523–3528 (2003).
So, D. et al. Supplementing dietary fibers with a low FODMAP diet in irritable bowel syndrome: a randomized controlled crossover trial. Clin. Gastroenterol. Hepatol. 20, 2112–2120 (2021).
Yao, C. K. et al. Effects of fiber intake on intestinal pH, transit, and predicted oral mesalamine delivery in patients with ulcerative colitis. J. Gastroenterol. Hepatol. 36, 1580–1589 (2021).
Jama, H. et al. Maternal diet and gut microbiota influence predisposition to cardiovascular disease in the offspring. Preprint at https://www.biorxiv.org/content/10.1101/2022.03.12.480450v1.full (2022).
Marques, F. Z. et al. Guidelines for transparency on gut microbiome studies in essential and experimental hypertension. Hypertension 74, 1279–1293 (2019).
Mirzayi, C. et al. Reporting guidelines for human microbiome research: the STORMS checklist. Nat. Med. 27, 1885–1892 (2021).
Caporaso, J. G. et al. Ultra-high-throughput microbial community analysis on the Illumina HiSeq and MiSeq platforms. ISME J 6, 1621–1624 (2012).
Bolyen, E. et al. Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2. Nat. Biotechnol. 37, 852–857 (2019).
Chong, J., Liu, P., Zhou, G. & Xia, J. Using MicrobiomeAnalyst for comprehensive statistical, functional, and meta-analysis of microbiome data. Nat. Protoc. 15, 799–821 (2020).
Acknowledgements
We would like to acknowledge the Monash Proteomics and Metabolomics Facility for SCFA measurement and the Monash Bioinformatics Platform for access to M3 servers. We also would like to acknowledge M. Schlaich and J. Sesa-Ashton for their help with recruitment and T. Veitch for help developing the recipes used in the trial. This work was supported by a National Heart Foundation Vanguard grant (102182), a National Health & Medical Research Council (NHMRC) of Australia project grant (GNT1159721) and NHMRC fellowships to D.M.K., G.A.H., J.M. and R.E.C. F.Z.M. is supported by a Senior Medical Research Fellowship from the Sylvia and Charles Viertel Charitable Foundation Fellowship and by National Heart Foundation Future Leader Fellowships (101185 and 105663). The Baker Heart & Diabetes Institute is supported, in part, by the Victorian Government’s Operational Infrastructure Support Program.
Author information
Authors and Affiliations
Contributions
F.Z.M., D.M.K., C.R.M. and J.M. conceived and designed the study. H.A.J. wrote the first draft of the report, with input from F.Z.M. Both H.A.J. and F.Z.M. accessed and verified the data and performed the statistical analyses. D.R.-J. (supervised by F.Z.M. and J.M.) coordinated the trial, recruited participants and collected samples and data. Y.S. helped with recruitment. M.N. (microbiome), R.E.C. and G.A.H. (blood pressure), D.A. and D.J.C. (metabolites) and H.A.J. (cytokines) contributed with methods. All authors had full access to all data in the study, revised the manuscript critically, approved the version to be published and had final responsibility for the decision to submit for publication.
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Peer review
Peer review information
Nature Cardiovascular Research thanks Levi Waldron, Noel T. Mueller and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
Additional information
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Extended data
Extended Data Fig. 1 HAMSB diet reduces in home systolic and diastolic blood pressure (BP).
a, Mean home systolic BP over 21-day HAMSAB intervention. b, Mean change in systolic BP relative to baseline and the mean difference in HAMSAB treated participants at b, Day1–3 and Day 17–20 and c, Day 1–3 and Day 14. d, Mean change in systolic BP relative to baseline and the mean difference in placebo treated participants at e, Day1–3 and Day 17-20 and f, Day 1-3 and Day 14. g, Overall drop in systolic BP relative to baseline and placebo-subtracted mean difference. h, Mean home diastolic BP over 21-day HAMSAB intervention. mean change in diastolic BP relative to baseline and the mean difference in HAMSAB treated participants at i, Day1-3 and Day 17-20 and j, Day 1-3 and Day 14. k, Mean change in diastolic BP relative to baseline and the mean difference in placebo treated participants at l, Day1-3 and Day 17-20 and m, Day 1-3 and Day 14. n, overall drop in diastolic BP relative to baseline and placebo-subtracted mean difference. n = 20/treatment group. Error bars represent ±SEM. Two-tail paired t-test.
Extended Data Fig. 2 Propionate, changes to the gut microbiome and plasma cytokines between placebo and HAMSAB.
a, HAMSAB diet did not change plasma propionate levels. n = 20/treatment group. Error bars represent ±SEM. Two-tail Wilcoxon test. b, Bray Curtis β diversity test showing principal coordinate analysis plot between baseline and the placebo arm. n = 18-19/treatment group. Shaded ellipsis representing the 95% confidence interval for each group. c-f, In participants randomised to the HAMSAB arm first, Ruminococcus gauvreauii (c-d) and Parabacteroides distasonis (e-f) prevalence was significantly reduced after the 3-week washout period. Showing n = 11 after data from 3 participants randomised into HAMSAB first were removed due to low number of reads. Mean ±SEM. Two-tail Wilcoxon test. Plasma levels of g, IL-6; h, IL-17A; i, IL-10; and j, IL-1b in placebo and HAMSAB treated participants. n = 20/treatment group. Error bars represent mean ± SEM. Two-tail paired t-test for panels g and i, two-tail Wilcoxon test for panels h and j.
Extended Data Fig. 3 The impact of HAMSAB diet on gastrointestinal pH and transit times measured by Smart Pill.
We observed no difference in a, gastric emptying time; b, small intestinal transit time; c, colonic transit, and d, whole gut transit time in hours. We observed no difference in colonic e, minimum and f, median pH, but observed a decrease in g, maximum pH. h, Summary of maximum colonic pH in placebo and HAMSAB relative to baseline. Placebo data from a participant who had antibiotics between visits 3 and 4 was removed, resulting in n = 6 for placebo and n = 7 for baseline and HAMSAB groups. One-way ANOVA adjusted for multiple comparisons, showing adjusted P-values. Error bars represent mean ± SEM.
Supplementary information
Rights and permissions
Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.
About this article
Cite this article
Jama, H.A., Rhys-Jones, D., Nakai, M. et al. Prebiotic intervention with HAMSAB in untreated essential hypertensive patients assessed in a phase II randomized trial. Nat Cardiovasc Res 2, 35–43 (2023). https://doi.org/10.1038/s44161-022-00197-4
Received:
Accepted:
Published:
Version of record:
Issue date:
DOI: https://doi.org/10.1038/s44161-022-00197-4
This article is cited by
-
Brain and hypertension: from sympathetic outflow to brain-focused blood pressure management
Hypertension Research (2026)
-
Microbial production of short-chain fatty acids attenuates long-term neurologic impairment after traumatic brain injury
Journal of Neuroinflammation (2025)
-
Parental diet and offspring health: a role for the gut microbiome via epigenetics
Nature Reviews Gastroenterology & Hepatology (2025)
-
Microbiota-derived butyrate alleviates asthma via inhibiting Tfh13-mediated IgE production
Signal Transduction and Targeted Therapy (2025)
-
“Gut Microbiota as a Therapeutic Target for Hypertension: Challenges and Insights for Future Clinical Applications” “Gut Microbiota and Hypertension Therapy”
Current Hypertension Reports (2025)


