Eating a high-fat “westernised” diet potentially increases the risk of food poisoning and reduces the efficiency of the immune system to fight infectious disease, researchers at University College Cork (UCC) have found.
The study of the effects of a westernised diet on the gut of mice showed that even short-term consumption increased the number of a particular type of cell, known as goblet cells, which are the target of infection by Listeria.
Listeria monocytogenes is a food-borne pathogen responsible for listeriosis, a serious infection usually caused by eating contaminated food.
It's particularly serious in pregnant women, the elderly and the immunocompromised.
The scientists, based at APC Microbiome Ireland, found the high-fat diet caused “profound changes” to the composition of microbiota (micro-organisms) in the gut and the immune system and also increased susceptibility to infections beyond the gut eg in the bloodstream.
Cormac Gahan, leader of the research study, said when listeria was introduced to mice by the blood-borne route, they had higher rates of infection.
Dr Gahan said initial findings showed a high-fat diet reduces specific types of bacteria in the gut microbiota. “And we think that reduction potentially has a negative impact on the host”.
He said their next step was to try and reintroduce the bacteria destroyed by diet and block infection. Bacteria could be reintroduced through the drinking water of the lab animal, for instance.
The scientists point out that increased human consumption of a ‘westernised’ diet has been linked to the dramatic rise in obesity and type 2 diabetes.
“Short-term consumption of the high-fat diet increased levels of Firmicutes bacteria in the gut which are associated with obesity,” said PhD student Vanessa Las Heras, who carried out the study.
"The effects of diet were also seen beyond the gut, with reduced levels of immunity throughout the body, local alterations to gastrointestinal cell function and changes to the gut microbiota that enhanced the progression of Listeria infection”.
Dr Gahan said the results suggest diet may be a significant influencer of resistance to infectious disease through effects on the gut microbiota and immune system.
He said it had "important implications for human health", including implications for research on infectious disease.
Dr Gahan said their work was about “moving towards an understanding of how bacteria affect the host, and harvesting this information so that we can bring it to bear on human health”.
The study is published in the journal Microbiome.