It makes sense that dietary fiber helps with digestion and elimination because of how it works in the digestive system, but new research shows how it directly affects the cardiovascular system at the same time.
In a study published in the journal Circulation, researchers from the Experimental and Clinical Research Center in Berlin detailed how the short-chain fatty acid propionate was beneficial in limiting the damage of high blood pressure in mice. Propionate is just one of the metabolites that are naturally produced by bacteria in the gut as a result of the ingestion of dietary fiber.
Scientists fed propionate to mice with elevated blood pressure and observed how their bodies reacted. Compared to the control group, the mice had less heart damage or abnormal enlargement which would make them susceptible to arrhythmia. Atherosclerosis and other vascular damage was decreased as well.
These findings reinforce the long-standing recommendation by nutrition experts to have a diet rich in fiber. Whole grains and fruits contain cellulose and inulin fibers that are used to create propionate and other beneficial molecules in the gut.
"Propionate works against a range of impairments in cardiovascular function caused by high blood pressure," says researcher Dominik N. Müller. "This may be a promising treatment option, particularly for patients who have too little of this fatty acid."
Dr. Nicola Wilck explained how propionate was able to affect the cardiovascular system. "Our study made it clear that the substance takes a detour via the immune system and thus affects the heart and blood vessels," Wilck said.
Researchers made it clear that immune cells are vital to the positive effects of propionate when they were able to deactivate regulatory T cells in the immune system and the positive effects of propionate disappeared.
One way propionate directly impacted the heart was in the frequency of arrhythmia. Researchers were able to use electrical stimuli to trigger an irregular heart beat in untreated mice 70 percent of the time but only 20 percent of the time in mice on propionate. Through the use of ultrasound and other methods of observation scientists saw that propionate reduced the blood pressure-related damage which significantly increased their survival rate.
"Previously, it had not been clear which fatty acid is behind the positive effects and how it works," says Wilck. "It might make sense to administer propionate or a chemical precursor directly as a drug—for example, when the blood of those affected contains too little of the substance.”