Gut reaction to the cholesterol count

A bacterium introduced into the intestine could help to reduce heart disease, says Bernard Dixon

Could a microbe be introduced into the body to lower the amount of cholesterol circulating in the bloodstream, and thus prevent or ameliorate coronary heart disease?The idea is strongly supported by research at Iowa State University in Ames, Iowa, where researchers have used a bacterium to reduce artificially raised cholesterol levels in rabbits. The treatment had no adverse effects on the animals, and the scientists believe that the same strategy could be of value in humans.

Cholesterol-lowering drugs are already available on the market, but, like most drugs, none are totally free of side-effects.A natural and harmless microbe that simply breaks down cholesterol in the body would be preferable to any type of synthetic drug.

The fact that raised cholesterol in the bloodstream promotes the development of atherosclerosis (narrowing of the arteries) is beyond question. Moreover, surveys worldwide have established that lowering the circulating cholesterol level diminishes the risk of a first heart attack and of subsequent attack in a person who has already suffered one. Some of these studies have shown that the danger of death from cardiovascular disease is also reduced.

Researchers atIowa State University aimed to introduce a microbe into the small intestine, to break down the cholesterol found in food and bile. The microbe would colonise the intestine, growing permanently alongside the many others that normally live there. The result would be to lessen the quantity of cholesterol absorbed from the small intestine into the bloodstream.

The researchers based their strategy on the isolation, several years ago, of bacteria capable of converting cholesterol to coprostanol, which is absorbed very poorly from the intestine. Unfortunately, most of these bacteria proved to be exceedingly difficult to culture in any quantity in the laboratory.

Last year, however, Donald Beitz and his colleagues in Ames announced that they had discovered a much more promising bacterium, which they called Eubacterium coprostanoligenes. They found it in pig manure (though it may originally have come from human faeces). The bacterium converted cholesterol into coprostanol and could be cultivated relatively easily at the laboratory bench. The researchers have given the bacterium to rabbits and found that it does indeed markedly reduce the level of circulating cholesterol.

Some microbes taken by mouth would be destroyed, or at least their numbers drastically diminished, by the highly acidic digestive juices in the stomach. The researchers first had to check this possibility. They found that Eu. coprostanoligenes could survive these conditions (simulated in a test-tube) for at least two hours and retain its ability to grow and attack cholesterol. Next they fed a diet rich in cholesterol (the human equivalent might be an excess of eggs or offal) to six New Zealand white rabbits each day for nearly two months. Predictably, this heightened the cholesterol level in their bloodstream. Three of the rabbits then received a culture of Eu. coprostanoligenes each day for 10 days, while the other three were given the same dose of the same bacterium after it had been killed by boiling.

As reported in this month's Letters in Applied Microbiology, administration of Eu. coprostanoligenes lowered considerably the quantity of cholesterol in the animals' bloodstream. From the end of the 10 days until the experiment was terminated over a month later, the rabbits that had received the living bacterium showed a reduction of more than a quarter in the cholesterol level as compared with those given the dead bacterium.

But was the microbe really having this effect by converting cholesterol into coprostanol, as the experimenters had hoped? They were able to confirm this explanation by examining the contents of the rabbits' digestive tracts and analysing them for both substances. As compared with the animals given the dead Eu. coprostanoligenes, those that had received the living bacterium showed much higher ratios of coprostanol to cholesterol. This showed that the bacterium, having colonised the rabbits' intestines, was indeed actively attacking cholesterol and turning it into coprostanol.

For people in many developed countries, coronary heart disease is a major killer, causing more deaths than all forms of cancer combined. Introducing the same bacterium to the human intestine could be particularly beneficial in individuals who have very high cholesterol levels not because of unwise eating habits but because they have the inherited condition called familial hypercholesterolaemia.

Donald Beitz is trying to improve the technique by varying factors such as the dose of Eu. coprostanoligenes and the period over which it is administered. Then, by courtesy of a food company which is trying to incorporate the bacterium into its yoghurt, they will see whether it works in humans. This could be the most health-giving yoghurt of all time.

Start your day with The Independent, sign up for daily news emails
ebooks
ebooksAn introduction to the ground rules of British democracy
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating
and  

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Home Care / Support Workers

£7 - £10 per hour: Recruitment Genius: This care provider is looking for Home ...

Recruitment Genius: Web Team Leader

£30000 - £35000 per annum: Recruitment Genius: One of the UK's leading web des...

Recruitment Genius: Client Manager

£27000 - £35000 per annum: Recruitment Genius: A growing, successful, friendly...

Recruitment Genius: Property Negotiator - OTE £20,000+

£16000 - £25000 per annum: Recruitment Genius: This family owned, independent ...

Day In a Page

Greece says 'No': A night of huge celebrations in Athens as voters decisively back Tsipras and his anti-austerity stance in historic referendum

Greece referendum

Greeks say 'No' to austerity and plunge Europe into crisis
Ten years after the 7/7 terror attacks, is Britain an altered state?

7/7 bombings anniversary

Ten years after the terror attacks, is Britain an altered state?
Beautiful evening dresses are some of the loveliest Donatella has created

Versace haute couture review

Beautiful evening dresses are some of the loveliest Donatella has ever created
No hope and no jobs, so Gaza's young risk their lives, climb the fence and run for it

No hope and no jobs in Gaza

So the young risk their lives and run for it
Fashion apps: Retailers roll together shopping and social networking for mobile customers

Fashion apps

Retailers roll together shopping and social networking for mobile customers
The Greek referendum exposes a gaping hole at the heart of the European Union – its distinct lack of any genuine popular legitimacy

Gaping hole at the heart of the European Union

Treatment of Greece has shown up a lack of genuine legitimacy
Number of young homeless in Britain 'more than three times the official figures'

'Everything changed when I went to the hostel'

Number of young homeless people in Britain is 'more than three times the official figures'
Compton Cricket Club

Compton Cricket Club

Portraits of LA cricketers from notorious suburb to be displayed in London
London now the global money-laundering centre for the drug trade, says crime expert

Wlecome to London, drug money-laundering centre for the world

'Mexico is its heart and London is its head'
The Buddhist temple minutes from Centre Court that helps a winner keep on winning

The Buddhist temple minutes from Centre Court

It helps a winner keep on winning
Is this the future of flying: battery-powered planes made of plastic, and without flight decks?

Is this the future of flying?

Battery-powered planes made of plastic, and without flight decks
Isis are barbarians – but the Caliphate is a dream at the heart of all Muslim traditions

Isis are barbarians

but the Caliphate is an ancient Muslim ideal
The Brink's-Mat curse strikes again: three tons of stolen gold that brought only grief

Curse of Brink's Mat strikes again

Death of John 'Goldfinger' Palmer the latest killing related to 1983 heist
Greece debt crisis: 'The ministers talk to us about miracles' – why Greeks are cynical ahead of the bailout referendum

'The ministers talk to us about miracles'

Why Greeks are cynical ahead of the bailout referendum
Call of the wild: How science is learning to decode the way animals communicate

Call of the wild

How science is learning to decode the way animals communicate