*High-fat diet, gut bacteria associated with insulin resistance, diabetes, kidney failure, researchers find
Areas with a higher number of fast food restaurants have more heart attacks, according to research presented at CSANZ 2019. The study also found that for every additional fast food outlet, there were four additional heart attacks per 100,000 people each year.
The 67th Annual Scientific Meeting of the Cardiac Society of Australia and New Zealand (CSANZ) takes place August 8 to 11, in Adelaide, Australia. The European Society of Cardiology (ESC) and CSANZ are holding joint scientific sessions as part of the ESC Global Activities programme.
Also, researchers have discovered how our choice of diet can weaken our gut immune system and lead to the development of diabetes.A growing body of research supports that during obesity, our immune system is often responding to components of bacteria that “leak” through the intestinal tissue and results in inflammation. In turn, inflammation can drive insulin resistance, which predisposes people to diabetes.In new research was published in Nature Communications this week.
Meanwhile, the author of the first study, Tarunpreet Saluja of the University of Newcastle, Callaghan, Australia said: “The findings were consistent across rural and metropolitan areas of New South Wales and after adjusting for age, obesity, high blood lipids, high blood pressure, smoking status, and diabetes. The results emphasise the importance of the food environment as a potential contributor towards health.”
“Ischaemic heart disease, including heart attack, is one of the leading causes of death worldwide,” continued Saluja. “It is known that eating fast foods is linked with a higher likelihood of fatal and nonfatal heart attacks. Despite this, there is rapid growth in the purchase and availability of fast food. This highlights the need to explore the role of food availability in the probability of having a heart attack.”
This retrospective cohort study included 3,070 patients admitted to hospital with a heart attack in the Hunter Region between 2011 to 2013. The database contained each patient’s home postcode, allowing the researchers to analyse their surrounding fast food environment.
Fast food outlets were defined as the ten most popular quick service food retailers in Australia, based on a population survey conducted in 2018. The researchers recorded the total number of outlets within each local government area and compared different areas to analyse the association between density of fast food restaurants and incidence of heart attack.
“Previous studies have shown that the poor nutritional value, high salt and saturated fat in fast food is connected to heart disease, yet the role of greater access to these restaurants has been less clear,” said Saluja.
“The ubiquitous presence of fast food is an important consideration for the ongoing development of rural and metropolitan areas,” he added. “The link with poor health adds a community lens to cardiovascular disease management and stresses the need to target this issue in future public health promotion strategies and legislation. This is why ESC guidelines recommend the regulation of fast food outlet density in community settings.”3
Professor Tom Marwick, Chair of the CSANZ 2019 Scientific Programme Committee, said: “This is an important paper that documents the association between fast foods and cardiac events, independent of risk factors. It will be crucial to explore whether this association is independent of the social determinants of disease, as we know that fast food outlets are often more common in disadvantaged areas. Nonetheless, the findings are a reminder that the fundamental drivers of cardiovascular disease burden may be altered by changes in public policy. The fact that the appropriate policy steps have not been taken, despite the cost of cardiovascular disease, remains as much a mystery in Australia as elsewhere in the world.”
Professor Jeroen Bax, Past President of the ESC and course director of the ESC programme at CSANZ 2019, said: “Tackling heart disease requires individual responsibility and actions at population level. This study highlights the impact of the food environment on health…”
In addition to regulating the location and density of fast food outlets, local areas should ensure good access to supermarkets with healthy food.”
Meanwhile, Dr. Dan Winer, Scientist, Toronto General Hospital Research Institute and the Department of Pathology at University Health Network (UHN), and his team, including graduate students Helen Luck and Saad Khan, and co-lead author, Dr. Shawn Winer at St. Michael’s Hospital, highlighted how a high fat diet influences one component of the gut immune system called B cells, specifically those that produce a protein called IgA.
“We discovered that during obesity, there are lower levels of a type of B cell in the gut that make an antibody called IgA,” said lead author Helen Luck.“IgA is naturally produced by our bodies and is crucial to regulating the bacteria that live in our gut. It acts as a defense mechanism that helps neutralize potentially dangerous bacteria that take advantage of changes to the environment, such as when we consume an imbalanced or fatty diet.”
In their experiments, they also observed that IgA deficient pre-clinical models, which lack protective IgA, had worsened blood sugar levels when fed a high fat diet. As well, transplantation of gut bacteria from these IgA deficient models into models that had no gut bacteria was able to transfer the disease, demonstrating that IgA can regulate the amounts of harmful bacteria in the gut during diet-related obesity.
In collaboration with a bariatric surgery research team at UHN led by Dr. Johane Allard and Dr. Herbert Gaisano, the team saw increased levels of IgA within the stool of patients soon after bariatric surgery, supporting the importance of IgA and the gut immune system in humans with obesity.
Overall, the research highlights a robust connection between high fat diets, obesity and the lack of gut IgA in promoting inflammation and insulin resistance. The knowledge that this class of antibodies regulate pathogenic bacteria, and protects against a “leaky gut,” and additional complications of obesity, is a powerful tool in the fight against diabetes.
“If we can boost these IgA B cells or their products, then we may be able to control the type of bacteria in the gut,” said Dr. Dan Winer. “Especially the ones that are more likely to be linked to inflammation and ultimately insulin resistance. Going forward, this work could form the basis for new gut immune biomarkers or therapies for obesity and its complications, like insulin resistance and type 2 diabetes.”
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