Daily Archives: 25 June, 2012

Gut bacteria and IBD

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The rise of inflammatory bowel diseases could be down to our shifting diets causing a “boom in bad bacteria”, according to US researchers.

Mouse experiments detailed in the journal Nature linked certain fats, bacteria in the gut and the onset of inflammatory diseases.

The researchers said the high-fat diet changed the way food was digested and encouraged harmful bacteria.

Microbiologists said modifying gut bacteria might treat the disease.

Inflammatory bowel diseases (IBDs), such as Crohn’s and ulcerative colitis, affect one in every 350 people in the UK. When the gut becomes inflamed it can lead to abdominal pain and diarrhoea.

The researchers at the University of Chicago said the incidence of the diseases was increasing rapidly.

They used genetically modified mice which were more likely to develop IBDs. One in three developed colitis when fed either low-fat diets or meals high in polyunsaturated fats. This jumped to nearly two in three in those fed a diet high in saturated milk fats, which are in many processed foods.

Inflammatory bowel disease

Inflammatory bowel disease

These saturated fats are hard for the body to digest and it responds by pumping more bile into the gut. This changes the gut environment and leads to a change in the bacteria growing there, the researchers said.

One bacterium in particular, Bilophila wadsworthia, was identified. It thrives in the extra bile produced to break down the fats. It went from being incredibly rare to nearly 6% of all bacteria in the gut in the high-fat diet.


Prof Eugene Chang, of the University of Chicago, said: “Unfortunately, these can be harmful bacteria. Presented with a rich source of sulphur, they bloom, and when they do, they are capable of activating the immune system of genetically prone individuals.”

However, he said this could lead to possible treatments as the gut bacteria could be “reshaped” without “significantly affecting the lifestyles of individuals who are genetically prone to these diseases”.

Commenting on the research, Dr Roy Sleator, from the Cork Institute of Technology, said: “Not only do the authors provide, what is in my opinion, the first credible explanation as to how Western diet contributes to the unusually high incidence in inflammatory bowel disease; they also suggest an effective means of dealing with such diseases, by simply reshaping the microbial balance of the gut.”

Spinach fights colon cancer

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Popeye the Sailor Man had the right idea when he guzzled cans of spinach. Because the cartoon character’s favourite food doesn’t just give you iron – it could also reduce your risk of colon cancer.

Researchers at Oregon State University found eating the green leafy vegetable reduced the damaging effects of a carcinogen found in cooked meat.

They were studying the complex biological effects of the cancer-causing substance on microRNA and cancer stem cells.

During their animal study they found that the consumption of spinach could partially offset the damaging effects of the carcinogen. In tests with laboratory animals, it cut the incidence of colon tumors almost in half, from 58 per cent to 32 per cent.

‘Cancer development is a complex, multi-step process, with damaged cells arising through various means,’ said researcher Mansi Parasramka.

‘This study showed that alterations of microRNAs affect cancer stem cell markers in colon cancer formation.

‘MicroRNAs are very small factors that do very big things in cells,’ she said.

Traditionally, cancer was thought to be caused by changes in DNA sequence, or mutations, that allowed for uncontrolled cell growth. That’s still true.

However, there’s also increasing interest in the role played by epigenetics, in which such factors as diet, environmental toxins, and lifestyle affect the expression of genes – not just in cancer, but also cardiovascular disease, diabetes, and neurological disorders.

Spinach

Spinach

Included in this epigenetic equation is the formation of microRNAs – once thought to be ‘junk DNA’ – which researchers were at a loss to understand. It’s now known that they influence which areas of DNA get expressed or silenced.

There are hundreds of microRNAs, and the OSU scientists monitored 679 in their experiments. When they don’t work right, problems can occur, including abnormal gene expression leading to cancer.


Professor Rod Dashwood said: ‘Unlike mutations which are permanent genetic changes in DNA, the good news about epigenetics and microRNA alterations is that we may be able to restore normal cell function, via diet and healthy life style choices, or even drug treatments.’

Epigenetics essentially makes every person biologically unique, Dashwood said, a product of both their genetics and their environment. That includes even identical twins.

The findings of the new study should lead to advances in understanding microRNAs, their effects on cancer stem cells, and the regulatory processes disrupted in disease development, the OSU scientists said.

This might lead one day to tailored or “patient specific” therapies for cancer, Dashwood said.

The research at OSU’s Linus Pauling Institute was recently reported in the journal Molecular Nutrition and Food Research, in work supported by the National Institutes of Health.