Research has found a high-salt diet reduced levels of Lactobacillus bacteria in mice and increased production of immune cells linked to high blood pressure.

Excessive salt intake wipes out levels of good bacteria in the gut and this can cause blood pressure to rise, a German study has found.

The findings have raised hope a simple probiotic could be used as a tool to help reduce the risk of heart attack and stroke caused by hypertension.

"This exciting research is the first to suggest that gut bacteria might act as the middle-man between salt and heart health, and provides a new therapeutic target to counteract salt-sensitive diseases," said Dr Hannah Wardill, postdoctoral researcher in Gastrointestinal Neuroimmune Interactions at the South Australian Health & Medical Research Institute and University of Adelaide.

Researchers at Berlin's Max Delbruck Center and Charite wanted to study the impact of a salty diet on the immune system. Their research, published in the journal Nature, found that a high-salt diet reduced the levels of Lactobacillus bacteria in mice and increased production of immune cells linked to high blood pressure.

When the mice had their guts replenished with the lost bacteria the effects were reversed. A pilot study in humans found similar results.

Earlier this year a study from the Baker Heart & Diabetes Institute in Melbourne showed that a diet high in fibre increased the abundance of bacteria that produced acetate.

This too was able to lower blood pressure and heart disease in mice.

In light of this new research, Australian Professor Brian Morris at the School of Medical Sciences and Bosch Institute at the University of Sydney has called for randomised clinical trials to confirm the heart benefits of probiotics in humans.

"People with a healthy traditional diet have high Lactobaccilus in their gut, but the high salt diet of people in more affluent countries probably explains why they have low Lactobaccilus levels and an epidemic of hypertension, as well as various autoimmune diseases," Prof Morris said.