In a recent study published in Nature's Signal Transduction and Targeted Therapy, scientists reviewed the therapeutic potential of and molecular mechanisms through which dietary interventions impact a wide range of human diseases, such as cardiovascular disease, autoimmune, neurodegenerative, and metabolic diseases, as well as cancer.
Study: Effects of dietary intervention on human diseases: molecular mechanisms and therapeutic potential. Image Credit: udra11/Shutterstock.com
Background
Diet and nutrition play a fundamental role in human health, with the quantity, composition, and quality of the diet, as well as meal timings, being important determining factors for the availability of nutrients, which, in turn, regulate physiological processes.
Recent research has also focused on understanding how diet influences disease trajectories. However, there still is a dearth of information on the impact of specific diet components on the prevention or risk of diseases.
Results from various epidemiological studies have found that specific dietary patterns modulate the risk of various diseases, including cancer.
While diets rich in sugars and saturated fats have been found to increase the risk of diabetes and cardiovascular disease, those consisting largely of vegetables, fruits, and fiber are believed to lower the risk of metabolic and cardiovascular diseases.
Similarly, diets high in processed meat and alcohol are thought to increase the risk of cancer, but the Mediterranean diet is believed to lower the risk of carcinogenesis.
Tumor metabolic pathways and nutrient availability
The researchers reviewed the existing knowledge on the differences in the nutrient requirements and metabolic pathways between the tumor microenvironment and the surrounding healthy tissues.
The immunosuppressive environment inside tumors is a result of the cancer cells depriving the immune cells of essential metabolites such as oxygen and glucose while increasing the levels of adenosine, lactase, and other mediators that further decrease immune cell function.
The metabolic reprogramming that occurs inside the tumor microenvironment impacts various immune cell subsets.
The major metabolic pathways in immune cells that are believed to be reprogrammed within the tumor microenvironment include the tricarboxylic acid cycle, glycolysis, the pentose phosphate pathway, oxidative phosphorylation, the amino acid pathway, and fatty acid synthesis.
The review examined each of these pathways in terms of the changes in nutrition requirements and metabolic characteristics inside the tumor microenvironment.
Dietary interventions and cancer
The impact of dietary interventions on diseases, including cancer, can be deciphered better with a thorough understanding of the metabolic pathways of macronutrients such as proteins, fats, and carbohydrates.
Systemic metabolism can be modulated by regulating the macronutrient intake and influencing the metabolic pathways utilized by these macronutrients.
Special diets such as ketogenic diets, caloric restriction diets, high-fat diets, fasting-mimicking diets, and even high-salt diets, as well as dietary restrictions, are based on the concept of systemic metabolism modifications through macronutrient intake modulations.
The review discussed these various dietary interventions in detail, providing a comprehensive summary of the molecular mechanisms through which specific diets influence clinical outcomes in patients with cancer.
The researchers also reviewed studies that evaluated the role of dietary factors in cancer treatment, especially the use of nutritional interventions to improve the efficacy of immunotherapy and other cancer treatments.
Caloric restrictions were found to increase the response of T cells to immunotherapy. In contrast, using caloric restriction mimetics has improved the effectiveness of chemotherapy and immunotherapy.
Caloric restriction has also been found to be effective in modulating the tumor microenvironment when combined with radiotherapy for cases of triple-negative breast cancer.
The review comprehensively analyzed the findings from various studies that have examined the effectiveness of specific dietary restrictions in combination with various cancer therapies in modulating the tumor microenvironment.
The scientists also discussed the changes induced in the gut microbiome through dietary interventions and the effectiveness of gut microbiome alterations in conjunction with cancer therapy.
Studies found that alterations in the gut microbiome diversity and composition due to dietary interventions change the levels of metabolites derived from microbiota that directly influence antitumor activity.
Dietary interventions and other diseases
The review also discussed the role of dietary interventions in preventing or delaying, or sometimes even inducing, the progression of cardiovascular, neurodegenerative, metabolic, and autoimmune diseases.
They examined the connection between nutrient availability, dietary patterns, and neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, epilepsy, and Huntington’s disease, among others.
The impact of dietary interventions on autoimmune disorders such as systemic lupus erythematosus, Hashimoto’s thyroiditis, inflammatory bowel disease, and multiple sclerosis was also covered in this review.
Conclusion
Overall, the findings from this review showed that dietary interventions play a significant role in human health and disease, with some interventions, by themselves or in conjunction with other therapies, slowing the progression of diseases such as cancer or improving the efficacy of treatment methods, and others increasing the risk of various diseases.
Study links air pollution to increased colorectal cancer risk through DNA changes