Bacteria make 90% of human bodies

Bacteria turn out to make up 90 per cent of the living cells in human bodies, The Daily Mail said in a recent article.

The human relationship with the single-celled friends is said to be so strong that some scientist have come to regard humans and their hitchhikers as one human-bacteria super-organism.

Cork Institute of Technology lecturer, Dr Roy D. Sleator, 36, from County Kerry in Ireland, has spent the last four years studying the subject.

'Bacteria have now come to be regarded as a virtual organ with the combined output far in excess of the liver,' said Dr Roy.

'Until recently the true role of our native bacterial populations was largely overlooked. However, new analysis of all the DNA from the environment has revealed the true diversity and utility of our microbial populations.

'Indeed, the human gut alone contains almost four and a half pounds of bacteria.'

But Dr Sleator is clear that the bacteria are there for humans' benefit - and without them people would not survive long.
'We are in essence only ten percent human - the rest is pure microbe,' said Dr Sleator.

'This bacterial-human interaction is for the most part symbiotic. Which means in return for food and board the bacteria help with digestion, vitamin production and bolstering our innate immune system.

'They protect us against infection by pathogens - so called bad bacteria.

'Animals that are bred to have no bacteria are far more susceptible to infection and have a reduced life expectancy compared to wild animals.

'This illustrates the important role of our bacteria.'

And it's good news for fans of probiotic yoghurt which are advertised for their ability to cultivate, 'friendly bacteria' in the human body - as long as these drink are consumed regularly for long periods.

'Eating probiotic yogurt can certainly help to bolster your good bacteria,' said Dr Sleator.

'But these bacteria are for the most part transitory - the majority pass through the body and fail to colonise.

'Regular administration needs to be maintained for results to be observed.

'Some physicians are now actively prescribing probiotic drinks to patients following antibiotic treatment to help replenish the good bacteria.'

There are about 500 different species of bacteria in each human body.

They multiply in an adult to form about 100 trillion individual cells - far more than the few trillion human cells that make up a single human being.