A ketogenic diet low in carbohydrates and high in fats has attracted attention as a weight loss tool, but now US researchers suggest that it can protect mice from influenza A virus. Feeding mice a keto diet for just one week reduced flu symptoms and the ability of the virus to replicate in the lungs.
In this study led by a team at Yale School of Medicine, a small number of specially bred mice were fed one of three different diets for seven days before being infected with an influenza A virus (Emily Goldberg et al, Science Immunology, 2019, 4 (41), eaav202). Mice fed a keto diet were less susceptible to infection and had a higher survival rate than mice on a high-carb diet.
The authors suggest the keto diet activates a subset of immune cells in the lungs – gamma delta T cells – not previously associated with the response to influenza. These cells enhance mucus production in the cell lining of the lung helping to trap the virus. When mice were bred without the gene that codes for gamma delta T cells, the keto diet provided no protection against the virus.
Mice fed a high carbohydrate, high fat diet also had a greater number of gamma delta T cells in the lung, but this did not protect against infection; neither did providing mice with mice with the byproduct – 1,3-butanediol – of a keto diet.
‘This study shows that the way the body burns fat to produce ketone bodies from the food we eat can fuel the immune system to fight flu infection,’ says co-senior author Vishwa Deep Dixit of Yale School of Medicine.
Kirsty Short of the University of Queensland comments that the diets and metabolism of mice and humans are very different and it remains unclear what this would mean for people on a keto diet. ‘However, where this study is significant is that it adds to the growing body of evidence that our diet plays an important role in determining one’s risk of both non-infectious diseases – eg cancer and diabetes – and infectious diseases, eg flu.’
‘What is remarkable is that ‘protective effects’ of a ketogenic diet were observed in mice fed for just seven days before infection,’ says Margaret Morris from the School of Medical Sciences at the University of New South Wales, Australia.
‘These observations raise a number of questions – could diet-induced changes in the gut microbiome play a role in modulating response to the virus? Will the effects last? An intriguing study,’ she added.