Interaction of Western Diet, Gut Microbiota, and Cancer Development

A review article published in a magazine Immunology seminarscientists have investigated the relationship between Western diet, the gut microbiota, and the development of cancer.

study: Effects of Western Diet on Microbiome and CarcinogenesisImage credit: Keri Delaney / Shutterstock

Background

A complex interplay between several modifiable factors, including diet, lifestyle and environment, greatly increases the risk of developing cancer. However, these factors can be appropriately modified to reduce cancer risk.

A healthy diet refers to consumption of moderate amounts of saturated fat, sugar, sodium, and cholesterol. increase.

Studies show that continued adherence to a Western diet may increase the risk of a variety of ailments, including cardiovascular disease, diabetes, obesity, and certain cancers. Diet is known to influence gut microbiota composition and immunological, neurological, and hormonal function.

Major Ingredients of the Western Diet

Western diets contain high amounts of saturated fat, refined carbohydrates, salt, sugar, and food additives that are associated with many health problems.

obesity

Fat is a high calorie food ingredient with three subtypes including unsaturated fat, trans fat and saturated fat. While unsaturated fats are associated with many health benefits, trans and saturated fats increase the risk of various health complications. Contains a lot of processed foods.

A study conducted in healthy adults found that a high-fat diet for 6 months significantly altered the composition of the gut microbiota, reduced short-chain fatty acids, and increased secondary bile acid production. is shown. Furthermore, a high-fat diet increases pro-inflammatory genes in the gut microbiota, causing mild systemic inflammation.

Animal studies have shown that alterations in the gut microbiota induced by a high-fat diet result in decreased mucosal immune responses, increased pretumor immune responses, and increased proliferation of intestinal epithelial and stem cells. . All these factors collectively increase the risk of developing and developing bowel cancer.

Accumulation of Gram-positive bacteria in the liver by a high-fat diet, together with dysregulation of bile acid metabolism, can lead to the induction of senescence-associated secretory phenotypes in hepatocytes. These events are collectively responsible for the development of liver cancer.

Microbiota alterations due to a high-fat diet may increase lipopolysaccharide biosynthesis and systemic levels, increasing the risk of breast, prostate and esophageal cancers.

Dietary fiber

Dietary fiber is a semi-digestible plant food component that aids in digestion and elimination. A variety of short-chain fatty acids are produced by partial fermentation and dietary fiber degradation mediated by the gut microbiota. Western diets contain far less plant-based fiber. Therefore, following this dietary pattern may reduce the production of beneficial microbial metabolites.

Chronic inflammation and ulceration of the colon (ulcerative colitis) is a significant risk factor for the development of colorectal cancer. Ulcerative colitis patients on a high-fiber, low-fat diet have been found to have less inflammation and microbiota abnormalities in their intestines and an increased amount of beneficial bacteria.

Studies conducted in animals have shown that dietary fiber production of the short-chain fatty acid butyrate is associated with increased anti-inflammatory, anti-tumor, anti-proliferative, and pro-apoptotic effects. Together, these factors help reduce the risk of intestinal tumor formation.

In mouse models of lymphoma, a high-fiber diet can beneficially alter gut microbiota composition and microbial metabolite levels, increase dendritic cells and cytotoxic natural killer cells, and subsequently induce antitumor responses. I already know.

Long-term intake of dietary fiber may increase the risk of cancer. For example, a highly soluble fermentable fiber diet has been shown to induce gut microbiota abnormalities in insulin-resistant obese-sensitive mice, increasing the risk of developing liver cancer.

Excessive formation of microbial fiber fermentation byproducts may increase cancer risk.One such by-product is short-chain fatty acid acetate, which is used by the liver for lipogenesis and is a non-alcoholic fatty liver disease and obesity.

A low-fiber diet may also decrease microbial carbohydrate fermentation and short-chain fatty acid synthesis, which may increase the risk of colorectal cancer.

carbohydrates

The Western diet contains many processed foods containing easily digestible carbohydrates. These types of foods have a high glycemic index due to their ability to raise glucose levels in the blood.

Studies have shown that a low-carbohydrate diet reduces the production of Gram-positive bacteria and butyrate in the small intestine and colon, reducing polyp formation. This type of low glycemic index carbohydrate also inhibits DNA degradation and cell proliferation in the colon.

A carbohydrate diet rich in resistant starch has been found to alter the composition of the gut microbiota, increasing formic and lactic acid production and decreasing propionic acid production. collectively reduce the risk of

Consumption of dietary sugar carbohydrates such as fructose and sucrose is known to increase obesity and may increase the risk of colorectal cancer.Furthermore, fructose may increase fat accumulation in the liver. It may also increase the risk of non-alcoholic fatty liver disease and liver cancer.

Other dietary ingredients

Western diets are rich in processed and ultra-processed foods that are high in salt. A high-salt diet has been shown to reduce the risk of certain types of cancer by inducing anti-tumor immunity through the gut microbiota, which is characterized by an increase in natural killer cells.

A cholesterol-rich Western diet is associated with dysregulated bile acids and indole derivatives, which collectively may increase the risk of liver cancer.

Emulsifiers used in processed foods are potentially harmful ingredients in the Western diet. These components may increase the risk of intestinal carcinogenesis by dysregulating the gut microbiota and inducing mild inflammation.

The currently available scientific literature indicates that key components of the Western diet significantly modulate the composition of the gut microbiota, which may increase the risk of various types of cancer.