Bowel diseases and high fat diets

Diets rich in milk could be behind the growth in cases of inflammatory bowel disease because they fill our guts with “bad bacteria”, a study on mice suggests.

The high amounts of fat we consume today is altering the way we digest our food and allowing harmful bacteria to flourish in our bodies, researchers said.

Changing the balance of bacteria in our guts could relieve the symptoms of the increasing number of people complaining of inflammatory bowel diseases (IBDs) which affect one in 350 people in Britain, they said.

Diseases like Crohn’s and ulcerative colitis – the condition which last year put Manchester United midfielder Darren Fletcher’s career on hold – are caused by the inflammation of the gut, causing symptoms including abdominal cramps and diarrhoea.

Researchers from the University of Chicago studied the effects of varying diets on mice which were genetically engineered to make them prone to IBDs.

One third of mice fed diets which were low in fat or high in polyunsaturated fats developed colitis, compared with two thirds of those fed high amounts of saturated milk fats.


Because these fats – a common component of processed foods – are hard to digest the body has to fill the gut with more bile, altering the balance of bacteria which grow there, the researchers said.

One type of bacterium called Bilophila wadsworthia, normally extremely rare in mouse gut, multiplied so much that it accounted for six per cent of all bacteria in the guts of mice fed the high saturated fat diet.

Prof Eugene Chang, who led the study, said it could lead to new treatments which allow the profile of gut bacteria to be “reshaped” without significantly changing patients’ lifestyles.

Dr Roy Sleator, of the Cork Institute of Technology, who was not involved in the study, told the BBC: “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.”

Probiotic yoghurts fight the carbs

After wolfing down a pizza you may want to finish with a probiotic yoghurt, after researchers found they help the body to break down carbohydrates.

Scientists from Washington University School of Medicine wanted to look at what impact, if any, live bacteria in popular yoghurts have on digestion.

They performed studies on mice as well as identical female twins using a yoghurt that had five strains of live bacteria.

The team found eating the yoghurt twice a day for seven weeks did not alter the mix of microbes in the intestines of the women or the mice.

However, when they took a closer look at the mice they found there were significant changes in some of the bacterial enzymes involved in metabolising carbohydrates.

Many of the key changes noted in the highly controlled laboratory environment were also found in the seven pairs of twins.

Probiotic yoghurt
Probiotic yoghurt

Study author Dr Jeffrey Gordon, said: ‘Carbohydrates are an important part of our diet, and the way they are broken down by gut microbes is an important part of digestive health.

‘A number of carbohydrates are quite complex and can only be digested by enzymes made by gut microbes.

‘We found that when the mice were given the bacterial strains found in the yogurt, at doses comparable to those consumed by humans, they could more efficiently break down certain classes of carbohydrates.’

Our guts contain millions of bacteria known collectively as the microbiota.

This complex system works to break down certain nutrients that our bodies could not otherwise digest, prevents the growth of harmful bacteria, produces nutrients such as vitamin K and biotin as well as hormones to tell our bodies when to store fat.

The research, which was published in Science Translational Medicine, could help scientists analyse the many health claims made by makers of probiotic yoghurts.

‘This is a proof of principle. We have developed an approach to test the health effects of probiotics that focuses on how those microbes influence the dynamic operations of our gut microbial communities,’ Dr Gordon said.

He added that their long-term goal was to develop ways to improve the nutritional value of the foods we eat.