Eating yogurt high in ‘good bacteria’ could help lower high blood pressure, according to new research.
In a scientific first, researchers have discovered diets high in salt are killing off beneficial bacteria in our guts.
Without these ‘friendly’ microbes, our bodies start producing cells that increase inflammation – making our blood vessels narrower, which puts people at risk of suffering a stroke or heart attack.
But the germs in the gut that are killed off by high-salt diets could be replaced by a dose of ‘good bacteria’ in a pro-biotic yogurt drink, scientists said.
Experiments on humans and mice fed the unhealthy diet found the treatment reduced inflammation-triggering cells that cause high blood pressure.
Yet, experts warn further studies are required before probiotics can reliably be linked to reduced blood pressure.
Professor David Relman from Stanford University in California, said: ‘Should hypertension be added to the list of conditions promoted by the gut microbiota? Future studies will no doubt tell.'
Yogurt therapies could tackle high blood pressure
Probiotics are commonly found in yogurts as well as fermented products such as sauerkraut.
The American and German team warned it was not a licence for people to consume as much salt as they like as long as they ate yogurt.
But the breakthrough could lead to yogurt-based therapies to tackle high blood pressure, or hypertension, that affects one-in-four Britons. A diet high in salt is a major risk factor.
Adults in the UK eat about 8.1g of salt a day - well above the recommendation of no more than 6g.
Salt drives bacteria in the gut that cause hypertension
Professor Eric Alm, a biological engineer at Massachusetts Institute of Technology, said: ‘I think certainly there’s some promise in developing probiotics that could be targeted to possibly fixing some of the effects of a high-salt diet.
‘But people shouldn’t think they can eat fast food and then pop a probiotic and it will be cancelled out.’
Professor Alm and colleagues showed a high-salt diet shrank the population of a certain type of beneficial gut bacteria called Lactobacillus murinus.
As a result pro-inflammatory cells of the immune system known as Th-17 - which have been linked with high blood pressure - grew in number.
In the study of healthy humans adding 6 grams of table salt to their daily diet for a fortnight reduced the lactobacillus bacteria in their gut.
Their blood pressure went up - along with their counts of Th-17 cells.
But when the participants - all male and aged 18 to 50 - were given a commercially available probiotic for a week before going on the high-salt diet their gut lactobacillus levels and blood pressure remained normal.
This followed similar results in mice. For two weeks table salt made up 4 percent of their diet - eight times more than normal.
This led to a drop in lactobacillus, more of the troublesome Th-17 cells - and a rise in blood pressure.
But when they were given a probiotic containing Lactobacillus murinus the inflammatory cells went down and hypertension was reduced.
It is still unclear exactly how Th-17 cells contribute to the development of high blood pressure and other ill effects of a high-salt diet.
'Profound potential for global health benefits'
Professor Alm said: ‘We’re learning the immune system exerts a lot of control on the body, above and beyond what we generally think of as immunity. The mechanisms by which it exerts that control are still being unravelled.’
It is hoped the findings published in Nature will shed more light on the association between a high-salt diet and disease.
Prof Alm said: ‘If you can find that smoking gun and uncover the complete molecular details of what’s going on you may make it more likely that people adhere to a healthy diet.’
Scientists have long known a high-salt diet can lead to cardiovascular disease. As it accumulates in the bloodstream the body retains more fluid to dilute it.
It means the heart and blood vessels have to work harder to pump the extra volume of water.
This can stiffen the blood vessels - potentially leading to high blood pressure, heart attack and stroke.
Recent evidence has also implicated the body’s immune system in some of the effects of a high-salt diet.
Professor David Relman, of Stanford University in California, reviewed the findings or the journal and said they have ‘profound potential.’
He said: ‘Should hypertension be added to the list of conditions promoted by the gut microbiota? Future studies will no doubt tell.
‘If this connection is real, one might predict - because of other variable factors - that the effects will be modest and restricted to a subset of individuals.
‘Nonetheless, even modest effects are more than worthy of further study, because of the profound potential for global health benefits.’
A shocking 16 million people in the UK suffer from high blood pressure - the biggest risk factor for stroke and heart attacks - with over half unaware they have the condition.
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