Could a moderate protein diet improve metabolism?

In a groundbreaking study from Waseda University, researchers have investigated whether a moderate protein diet could improve metabolic health

The groundbreaking study by Waseda University has investigated whether a moderate protein diet could improve metabolic health.

The age-old adage “You are what you eat” emphasizes the profound impact of our dietary choices on our overall health and well-being.

As we age, our nutritional requirements evolve, and maintaining metabolic health becomes crucial for an extended period of disease-free living.

In recent years, scientific investigations have focused on the relationship between dietary interventions and longevity, with studies showcasing the influence of calorie and protein intake on the health and lifespan of both rodents and primates.

The association between macronutrients with cardio-metabolic health and aging

Additionally, emerging research in mice has highlighted the association between macronutrients with cardio-metabolic health and aging. These macronutrients include the following:

• Proteins
• Carbohydrates
• Fats

However, the optimal amount of protein necessary for maintaining metabolic health remains a question to be answered.

How did researchers conduct the study?

The researchers recruited male C57BL/6NCr mice at two different stages of life: young mice aged 6 months and middle-aged mice aged 16 months.

These mice were then subjected to isocaloric diets with varying protein content, ranging from 5% to 45%, for a duration of two months.

After the experimental period, the effects of the different protein diets were assessed through comprehensive measurements, including skeletal muscle weight, liver and plasma lipid profiles, and self-organizing map (SOM) cluster analysis of plasma amino acid profiles.

How much protein do we really need?

When asked about the motivation behind their study, Kondo explains, “The optimal balance of macronutrients for ideal health outcomes may vary across different life stages.

“Previous studies show the possibility of minimizing age-specific mortality throughout life by changing the ratio of dietary protein to carbohydrates during the approach to old age in mice.

“However, the amount of protein that should be consumed to maintain metabolic health while approaching old age is still unclear.”

‘Protein requirements change through the course of life’

Kondo adds, “Protein requirements change through the course of life, being higher in younger reproductive mice, reducing through middle age, and rising again in older mice as protein efficiency declines.

“The same pattern is likely to be observed in humans. Therefore, it could be assumed that increasing daily protein intake in meals could promote the metabolic health of people.

“Moreover, ideal dietary macronutrient balance at each life stage could also extend health span.”

Impact of a moderate protein diet on metabolic health

During their investigation, the research team made significant observations regarding the influence of different protein diets on the metabolic health of mice.

They found that a low-protein diet resulted in the development of mild fatty liver, characterized by elevated hepatic lipid levels, particularly in middle-aged mice compared to their younger counterparts.

Conversely, a moderate-protein diet exhibited favourable effects by reducing blood glucose concentrations and lipid levels in both the liver and plasma of mice.

These findings suggest that a moderate protein intake, ranging from 25% to 35%, contributes to improved metabolic health in both young and middle-aged mice.

How protein diets affect plasma amino acid concentrations

The researchers also analyzed the plasma amino acid concentrations in mice of different age groups to better understand the impact of varying protein diets.

They found that the levels of individual amino acids in the plasma varied depending on age and the protein content of the diet.

To validate these findings, they utilized a self-organizing map (SOM) analysis of the plasma amino acid profiles, which revealed distinct patterns linking protein intake with hepatic triglyceride and cholesterol levels.

These findings offer valuable insights into the complex relationship between protein intake, plasma amino acid concentrations, and metabolic health in mice.

This study sets the stage for further research and potential applications in determining the optimal protein intake for maintaining metabolic health in ageing individuals.

The collaborative team included Dr. Takuya Chiba from the Faculty of Human Sciences at Waseda University, Dr. Akihito Ishigami from the Molecular Regulation of Aging 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.