The impact of different dietary structures on gut microbiota.

Habitual or long-term diet has a crucial impact on the development of several chronic diseases in adults. Additionally, the role of the gut microbiome in the development of some of these chronic diseases is becoming increasingly evident. The regulation of the health effects of diet by the gut microbiome suggests that changes in the composition of the gut microbiome may be a potential mechanism linking long-term diet to chronic diseases. In fact, long-term diet can have profound and lasting effects on the gut microbiome. It also induces the growth and proliferation of specific gut bacteria to achieve ecological balance in the gut microbiome. Therefore, exploring the relationship between long-term diet and microbiome composition is a topic worthy of long-term research. Clearly, the nutritional components of the diet determine their relationship with the composition of the gut microbiome. There is a synergistic effect of nutrients and foods with the matrix in dietary habits, which will enhance our understanding of the diet-microbiome relationship. In fact, a large and growing body of epidemiological evidence reveals a significant impact of high nutrient intake on microbiome composition. The three macronutrients—carbohydrates (including fiber), proteins, and fats—may reach the gut microbiome after escaping primary digestion due to their intake exceeding digestibility, inherent structural complexity, and the inability of human enzymes to metabolize them. Since the effects of macronutrients on microbiome composition differ, and different microbes have different metabolic capabilities, an independent relationship between macronutrients and microbiome composition is needed to explore their relationship.

Although the relationship between long-term high nutrient intake and adult microbiome composition has been well established in adulthood, there is insufficient evidence to indicate the impact of long-term diet on microbiome, especially its influence on adult microbiome composition during early life.

In the past decade, the prevalence of metabolic diseases, primarily overweight, obesity, and type 2 diabetes, has been rising globally. Independent risk factors for type 2 diabetes include genetics, ethnicity, overweight/obesity, and various other factors. Therefore, type 2 diabetes is also defined as a global metabolic disease caused by overweight/obesity. Given the varying social strata and economic income of the population with metabolic diseases, it is extremely important to develop a simple, practical, and inexpensive intervention method. Various dietary patterns, such as the Western diet, Mediterranean diet, low-calorie diet, vegetarian diet, and longevity diet, can all impact the gut microbiome. Changes in the gut microbiome can directly affect the host's metabolic status. Research shows that a reasonable gut microbiome structure is beneficial for host health. However, adverse interactions between the host and gut microbiome can lead to weight gain and metabolic dysfunction. Currently, the mechanisms by which different dietary patterns regulate metabolism through the gut microbiome are not fully understood. Therefore, clarifying the effects of each dietary pattern on the gut microbiome and metabolism is an important theoretical basis for dietary interventions targeting different metabolic diseases.

Table: Mechanisms by which different dietary patterns regulate metabolism through the gut microbiome

In summary, the Western dietary pattern is one of the risk factors leading to metabolic diseases in individuals. The Mediterranean diet (MD), low-calorie dietary pattern, vegetarian pattern, and longevity dietary pattern have been widely applied as simple, practical, and inexpensive therapeutic means in dietary treatment for patients with metabolic diseases such as obesity and type 2 diabetes, all of which have effects on improving blood sugar, insulin resistance, and chronic inflammation. However, the MD's effect on weight control is not significant; the long-term intervention effects of low-calorie diets and longevity dietary patterns are still unclear; and the vegetarian pattern carries the risk of lacking essential nutrients. These issues require further research. Regarding the gut microbiome, the MD, low-calorie dietary pattern, and vegetarian pattern can positively influence metabolism through the gut microbiome, helping to prevent and treat non-alcoholic fatty liver disease (NAFLD), obesity, and type 2 diabetes. Both the Western dietary pattern and low-calorie dietary pattern increase the number of gut Firmicutes to help the host extract more energy from food. The vegetarian pattern and low-calorie dietary pattern both lead to a decrease in beneficial bacteria in the gut, indicating that the long-term intervention effects of these two dietary patterns on patients still need further observation. The longevity diet has characteristics that can improve metabolism through the gut microbiome, but the specific effects require further research. Additionally, some studies have shown that high-protein dietary structures can also have positive metabolic effects on individuals with obesity and type 2 diabetes through the gut microbiome, but these dietary structures have not yet been transformed into established dietary patterns, so the information in this article can only serve as dietary reference.

References

[1] Long-term dietary intake from infancy to late adolescence is associated with gut microbiota composition in young adulthood.

[2] Research progress on the effects of different dietary patterns on individual metabolism and gut microbiota [J]. Chinese Journal of Endocrinology and Metabolism