Dietary protein and experimental carcinogenesis.

Area of Science:

• Oncology
• Nutritional Science
• Biochemistry

Background:

• Carcinogenesis is influenced by dietary factors including protein, fat, and overall calorie intake.
• Research on protein's role in cancer often involves protein underfeeding and feed restriction studies.
• Tumor growth, whether spontaneous, chemically induced, or transplantable, can be affected by protein intake levels.

Purpose of the Study:

• To review the influence of protein, protein-fat interactions, and calorie intake on carcinogenesis.
• To examine how varying protein quantities and amino acid profiles impact tumor development.
• To synthesize findings on the relationship between protein intake and the incidence of chemically induced cancers.

Main Methods:

• Review of existing literature focusing on protein underfeeding and feed restriction models.
• Analysis of studies investigating the effects of protein quantity and amino acid supply on tumor growth.
• Examination of research on chemically induced cancers (colon, mammary, liver) at different protein intake levels.

Main Results:

• Optimal or reduced protein intake generally inhibits tumor growth.
• Increased protein intake can enhance carcinogen metabolism, with tumor incidence depending on metabolite activity.
• Chemically induced cancer incidence varies with carcinogen, protein level, and administration details; high protein diets sometimes show lower incidence due to reduced feed intake.

Conclusions:

• Generalizing mechanisms of protein's effect on cancer is challenging due to diverse experimental models and protocols.
• Nutritional principles and species-specific requirements must be considered in protein-cancer research.
• Further research is needed to clarify the complex relationship between protein intake and carcinogenesis.