Western Diet Linked to Gut Inflammation and Chronic Diseases, Study Finds

In a recent study published in the journal Best Practice & Research Clinical Gastroenterology, researchers highlighted the effect Western diet can have on the risk of developing gut inflammation and chronic diseases including inflammatory bowel disease (IBD) and Alzheimer’s disease.

Western diet is widely recognized for its high content of unhealthy fats, refined grains, sugar, alcohol, and other harmful elements.

Western diets are high in processed meats, especially red meat, high-fat dairy, and salt, while being low in unprocessed fruits and vegetables, whole grains, fish, nuts, and seeds. This results in a diet low in fiber, vitamins, minerals, and antioxidants.

The gut microbiota, a complex ecosystem of microbes in the human gut, plays a crucial role in health by digesting food, providing essential vitamins, protecting against pathogens, maintaining the intestinal barrier, and supporting the immune system. Diet significantly influences the composition of gut microbiota. High-fat diets reduce the number of beneficial bacteria and disrupt the gut barrier. Western diets, in particular, impair gut structure and function, decreasing the abundance of microbes that promote a healthy gut barrier.

In the study, researchers compared the Western diet to the Mediterranean diet, noting that the Mediterranean diet includes less processed food and more fruits, vegetables, and plant-based proteins. They emphasized the importance of certain bacteria which are linked to better gut health and maintaining the gut lining. These bacteria are also associated with greater lean muscle mass.

The results showed that a diet high in saturated fat is linked to fewer beneficial microbes in the gut. Additives like artificial sweeteners also reduce the amounts of helpful bacteria. Eating fast food more than once a week is associated with a higher risk of inflammatory bowel disease (IBD). Poor dietary habits can increase the risk of ulcerative colitis by 43% and Crohn’s disease by 27%.

Additionally, high intakes of meat and fish are linked to an increased risk of IBD, while egg and dairy consumption are not.

Overall, the findings suggest that consuming large amounts of red meat, ultra-processed foods, sugar, and saturated fat may raise the risk of developing IBD and irritable bowel syndrome (IBS).

“This type of diet helps to increase our cholesterol level in the blood, and ultimately is bad for the health because cholesterol leads to heart disease and many other complications. And as a consequence, diabetes, and metabolic disorder develop. But there are a lot of studies showing that the diet not only alters metabolism but also it shifts the microbiome composition,” said Hasan Zaki, associate professor at UT Southwestern Medical School.

Reference: Andrea Severino, Ege Tohumcu, Luca Tamai, Pasquale Dargenio, et al.; The microbiome-driven impact of western diet in the development of noncommunicable chronic disorders, Best Practice & Research Clinical Gastroenterology; 2024,; https://doi.org/10.1016/j.bpg.2024.101923.