In a new study by Waseda University researchers, young and middle-aged mice were fed isocaloric diets with varying amounts of protein. Mice consuming moderate amounts of dietary proteins (25% and 35%) exhibited lower blood glucose, and hepatic and plasma lipid levels.
Newswise — As the saying "You are what you eat" states, the food we consume impacts our well-being and length of existence throughout our lifetime. In reality, a direct link exists between age-related nutritional needs and metabolic well-being. Adequate nourishment based on age aids in preserving metabolic health, thereby enhancing the duration of a healthy life without illness and an individual's overall lifespan. Various dietary interventions involving diverse calorie and protein intake have demonstrated the ability to enhance the well-being and lifespan of both rodents and primates. Furthermore, recent research has also identified a connection between dietary macronutrients (proteins, carbohydrates, fats) and cardiovascular-metabolic health as well as aging in mice. Nevertheless, the precise protein intake required to maintain metabolic health remains unknown.
In an April 28, 2023 publication in GeroScience, Assistant Professor Yoshitaka Kondo of Waseda University, Japan, led a research team to investigate the optimal amount of dietary protein required to enhance metabolic health in aging mice. The team, which included Dr. Takuya Chiba from the Faculty of Human Sciences at Waseda University, Dr. Akihito Ishigami from the Molecular Regulation of Aging department at the Tokyo Metropolitan Institute for Geriatrics and Gerontology, Dr. Hitoshi Aoki from the Research and Development Division at Nichirei Foods Inc, and Dr. Shin-Ichiro Takahashi from the Department of Animal Sciences and Applied Biological Chemistry at the Graduate School of Agricultural and Life Sciences, University of Tokyo, conducted a study involving young (6 months old) and middle-aged (16 months old) male C57BL/6NCr mice. These mice were fed isocaloric diets with varying protein content ranging from 5% to 45% over a period of two months. The effects of the different protein diets were evaluated by assessing measurements such as skeletal muscle weight, lipid profiles in the liver and plasma, and conducting self-organizing map (SOM) cluster analysis of plasma amino acid profiles.
When inquired about the motivation behind their research, Kondo elaborates, "The ideal composition of macronutrients for achieving optimal health outcomes might differ at various life stages. Previous research indicates the potential to minimize age-related mortality by altering the ratio of dietary protein to carbohydrates as mice approach old age. Nevertheless, the precise quantity of protein required to sustain metabolic well-being during this period remains uncertain."
The research team made several noteworthy observations. They found that mice on a low-protein diet exhibited mild fatty liver, with higher levels of hepatic lipids in middle-aged mice compared to young mice. In contrast, mice on a moderate-protein diet demonstrated reduced blood glucose concentrations and lower levels of lipids in both the liver and plasma. These findings suggest that a moderate-protein diet, specifically with protein content ranging from 25% to 35%, contributed to better metabolic health in both young and middle-aged mice.
Upon investigating the impact of different protein diets on plasma amino acid concentrations in mice of different age groups, the researchers noticed that the levels of individual amino acids in the plasma fluctuated with age and the protein content in the diet. The team employed self-organizing map (SOM) analysis of plasma amino acids to confirm these findings. Additionally, the SOM analysis of plasma amino acid profiles provided insights into the relationship between different protein intake levels and the varying amounts of hepatic triglycerides and cholesterol levels. This analysis revealed correlations between protein intake, plasma amino acid profiles, and metabolic markers such as hepatic triglycerides and cholesterol levels.
In discussing the implications of their study on public health, Kondo highlights the dynamic nature of protein requirements throughout life. He explains that protein needs are higher in younger reproductive mice, decrease during middle age, and then increase again in older mice due to declining protein efficiency. This pattern is likely to be observed in humans as well. Based on these findings, Kondo suggests that increasing daily protein intake in meals may promote metabolic health in people. Furthermore, he suggests that achieving an ideal balance of dietary macronutrients at each life stage could potentially extend the health span, which refers to the period of life spent in good health without diseases. These insights highlight the importance of considering age-specific protein requirements and overall macronutrient balance for promoting metabolic health and enhancing overall well-being in individuals.
In conclusion, a balanced diet with moderate amounts of protein could be the key to a long and healthy life.
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