How gut bacteria can prevent ill effects of high BP

Gut bacteria can help defend against heart and vascular damage caused by high blood pressure, a study in mice has found.

Gut microbes produce fatty acid propionate -- which calms the immune cells that drive up blood pressure from -- natural dietary fibre.

The substance defends against the effects of high blood pressure, including atherosclerosis and heart tissue remodelling, researchers said.

A large extent of our well-being depends on what bacterial guests in our digestive tract consume. Gut flora help the human body to utilise food and produce essential micronutrients, including vitamins, they said.

Beneficial gut microbes can produce metabolites from dietary fibre, including a fatty acid called propionate.

The research published in the journal Circulation showed how this substance protects against the harmful consequences of high blood pressure.

Researchers from the Experimental and Clinical Research Center (ECRC) in Germany fed propionate to mice with elevated blood pressure. Afterwards, the animals had less pronounced damage to the heart or abnormal enlargement of the organ, making them less susceptible to cardiac arrhythmia.

Vascular damage, such as atherosclerosis, also decreased in mice.

"Propionate works against a range of impairments in cardiovascular function caused by high blood pressure," said research group leader Dominik N Muller.

"This may be a promising treatment option, particularly for patients who have too little of this fatty acid," said Muller.

"Our study made it clear that the substance takes a detour via the immune system and thus affects the heart and blood vessels," said Nicola Wilck and Hendrik Bartolomaeus from the ECRC, who have been working together on the project for nearly five years.

In particular, T helper cells, which enhance inflammatory processes and contribute to high blood pressure, were calmed.

This has a direct effect on the functional ability of the heart, for example. The research team triggered heart arrhythmia in 70 per cent of the untreated mice through targeted electrical stimuli.

However, only one-fifth of the animals treated with the fatty acid were susceptible to an irregular heartbeat.

Further investigations with ultrasound, tissue sections, and single-cell analyses showed that propionate also reduced blood pressure-related damage to the animals' cardiovascular system, significantly increasing their survival rate.

When researchers deactivated a certain T cell subtype in the mice's bodies, known as regulatory T cells, the positive effects of propionate disappeared. The immune cells are therefore indispensable for the substance's beneficial effect.

The results explain why a diet rich in fibre, which has been recommended by nutrition organisations for many years, helps prevent cardiovascular diseases.

Whole-grain products and fruits, for example, contain cellulose and inulin fibres, from which gut bacteria produce the beneficial molecules like propionate, a short-chain fatty acid with a backbone of just three carbon atoms.