Researchers in Australia have demonstrated a specially engineered form of fermentable fiber can lower blood pressure in patients with hypertension. The randomized, placebo-controlled trial revealed just three weeks of dietary supplementation decreased blood pressure in hypertensive patients as effectively as currently used drugs.
Doctors have long suggested dietary changes should be the first option to treat hypertension in patients. The intervention is known as DASH (Dietary Approach to Stop Hypertension), and it has proven to be incredibly effective at lowering blood pressure in many patients.
Exactly how DASH lowers blood pressure, however, is still the source of much research. The most common hypothesis is the diet generates beneficial changes to the gut microbiome, increasing the generation of short-chain fatty acids (SCFAs), which subsequently leads to improvements in blood pressure.
Francine Marques, from the Monash University School of Biological Sciences, has been investigating the association between these SCFA metabolites and blood pressure for several years. Prior preclinical studies have shown acetate and butyrate in particular can lower blood pressure in animal models.
"These metabolites have untapped translational potential," explained Marques. "Our previous studies found that acetate and butyrate, two microbial SCFAs, decreased blood pressure in mice. However, this method would require patients to ingest SCFAs 24/7, making it unsuitable for humans."
So Marques and colleagues wondered whether a type of engineered fiber could be deployed to help our gut microbes deliver consistent high levels of beneficial SCFAs. The researchers turned to a fiber known as high-amylose maize starch, which can be modified to incorporate acetate and butyrate. The ultimate product is referred to as HAMSAB (acetylated and butyrylated high-amylose maize starch).
As our gut microbes ferment HAMSAB, high volumes of acetate and butyrate are released into the colon. The question this clinical trial set out to answer was whether HAMSAB supplementation in patients with hypertension can effectively lower blood pressure.
Twenty participants with untreated hypertension were recruited. For three weeks the participants consumed daily supplements of either HAMSAB or placebo. After a three-week washout period, the placebo and HAMSAB groups switched supplements, so by the end of the experiment all 20 participants had tried both interventions.
"In HAMSAB-treated hypertensives, 24-hour systolic blood pressure dropped 6.1 mmHg," Marques announced. "This is equivalent to one blood-pressure-lowering drug and has important clinical implications."
Blood tests revealed the HAMSAB supplementation significantly increased circulating levels of acetate and butyrate. These plasma levels were higher than could be achieved through standard dietary interventions.
Plus, the researchers saw the HAMSAB supplements alter each patient's gut microbiome composition, with increased levels of acetate- and butyrate-producing bacteria. According to Marques the findings back up the hypothesis suggesting microbiome-produced SCFAs play a role in regulating human blood pressure.
"This supports clinical and experimental findings that gut microbiota alterations, particularly SCFA-producer depletion, may predate hypertension," added Marques. "Thus, fermentable fibers like HAMSAB may re-establish gut microbial communities that produce SCFAs."
The new research is obviously only based on a small cohort of human subjects, so there is plenty more work to do before anything like this becomes clinically available. It's unclear whether HAMSAB supplements will specifically be the focus of future research but the findings do make clear modulating SCFA levels via the gut microbiome can effectively treat hypertension.
The new study was published Nature Cardiovascular Research.
Source: Monash University
