Ted Dinan, Professor of Psychiatry at UCC, neuroscience expert and author of more than 200 research papers and books.

You've heard of heart, lung and liver transplants - but imagine transplanting bacteria in the gut of a healthy person to the digestive system of somebody suffering from Parkinson's Disease. Or diabetes. Or even dementia.

Science has already found ways to treat the nasty C. Difficile bacteria - a bug-bear for many frail elderly people, which can cause severe diarrhoea and is very difficult to treat successfully.

However, says Ted Dinan, one of the most cutting-edge areas of science currently is the transplantation of the microbiota of a healthy individual to the gut of a person suffering as a result of having the Clostridium Difficile bug.

Scientists, he says, are now hoping to build on this by exploring the possibility of using microbiota transplants to treat a range of disorders from Parkinsown's Disease to diabetes and even dementia.

Our microbiota, or bugs, can be linked to a range of problems, he believes, including obesity and depression:

"There may be some individuals whose obesity may be partly driven by gut microbes," he explains, adding that our gut bacteria also significantly influence the way that our brains work:

"The reality is that there are many genes in these bacteria which produce substances that we cannot provide ourselves."

These include essentially fatty acids, folic acid, which many women take when they are pregnant, and tryptophan, an important amino-acid which enables the production of serotonin in the brain. Serotonin is a crucial regulator of our mood.

In fact, he says, the bacteria in the gut can produce hundreds, if not thousands of chemicals, a large number of which can influence the workings of the brain - such as neuro-transmitters like dopamine, which is released by nerve cells to send signals to other nerve cells.

"They produce substances that we must have - but which we cannot produce ourselves, such as serotonin or 5-HT.

"These are the chemicals that anti-depressants work on," he explains.

Our microbiota, he explains, produces a lot of chemicals that we cannot manufacture, and which we need - it's a kind of swap - we feed the bacteria the food they need, and they in turn produce the chemicals that we need.

Research has shown, says Dinan - who has worked in research laboratories on both sides of the Atlantic and holds a PhD in Pharmacology from the University of London - that if the bacteria in one's gut are significantly altered, it can increase your tendency to obesity:

This is because some microbes can break down and release more calories from your diet than others.

"Therefore, if you have the wrong kind of bacteria releasing more calories into your bloodstream, it can increase your risk of obesity."

And there's more. Research has also found that if a child under the age of two has been exposed to several courses of antibiotics, that child's risk of adult obesity is greatly increased, he says.

And not only that - how a newborn baby is delivered and the kind of food it is fed can have a significant effect on the bacteria in its gut.

"If one is born through the vagina, the vaginal bacteria we get in our intestine are those of the mother. However if a baby is born through Caesarean section, the baby picks up the bacteria from the environment and the mother's skin.

"That means that for the first two or three years, a baby born by Caesarean section has a different set of bacteria in the gut than a baby born vaginally.

"We are researching the long-term health implications of this - we believe there may be long-term health implications from Caesarean deliveries."

While there are many cases where a Caesarean delivery is essential, there is a school of thought that there may be consequences "that have not been previously considered, as a result of delivering babies by Caesarean section," says professor Dinan.

What the baby is fed has an effect on its microbiota, he says: "There is no doubt that while formula milk has become closer to breast milk, it is not the same as breast milk and if a baby is fed breast milk its microbiota are different.

"I would say the microbiota that develop in a breast-fed baby is better than the microbiota of a formula-fed baby".

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