A high-fat “western” diet reduces the efficiency of the immune system to fight infections and increases susceptibility to food-poisoning bugs, according to Irish researchers.
Feeding mice a “westernised” diet, which is high in fat and low in fermentable fibre, affected both the immune system and the bacteria resident in the gut – known as the gut microbiota.
The vulnerability was identified with the common food-borne pathogen Listeria monocytogenes by researchers based at APC Microbiome, which is attached to University College Cork.
Even short-term consumption of a high-fat diet was found to increase the number of “goblet cells” in the gut, which are the target for infection by Listeria, as well as causing profound changes to the microbiota composition and immune system.
The diet also increased susceptibility to infections beyond the gut.
Increased human consumption of a westernised diet has been linked to the dramatic rise in conditions such as obesity and type-2 diabetes, and research has demonstrated the direct effects of dietary fats upon both the immune system and the gut microbiota.
Serious disease
Listeria monocytogenes is a human pathogen found in contaminated foods that can cause serious disease, particularly in pregnant women, older people and those whose immune system is compromised.
"Short-term consumption of the high-fat diet increased levels of Firmicutes bacteria [including Listeria strains] in the gut, which are associated with obesity," said researcher Vanessa Las Heras, who carried out the study, the findings of which are published in the journal Microbiome.
“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,” she added.
Their results suggest diet may be a significant influencer of resistance to infectious disease through effects on the gut microbiota and immune system, said Dr Cormac Gahan, leader of the study, which was funded by the EU Horizon 2020 programme and Science Foundation Ireland.
“This has important implications for human health, especially during pregnancy, in old age and in immuno-compromised individuals. It also has more general implications for research on infectious disease,” he added.
