The relationship between diet and longevity is a complex topic, and while research in this area is ongoing, it is important to proceed with caution. While some studies have suggested that a moderate protein diet may have potential longevity benefits, it is only one of many factors that can influence overall health and lifespan.
Consuming nutritious foods can improve metabolic health and slow the ageing process. But what are the appropriate dietary macronutrient amounts to help achieve this? To find out, Japanese researchers fed young and middle-aged male mice isocaloric diets with varying amounts of protein. They discovered that mice fed moderate-protein diets had better metabolic health. These findings could provide valuable insights into developing nutritional interventions and improving metabolic health in people.
The type of food we eat influences our health and longevity throughout our lives, as the proverb “You are what you eat” states. In fact, there is a direct relationship between age-related nutritional requirements and metabolic health. Optimal nutrition for age can help maintain metabolic health, thereby increasing an individual’s health span (period of life without diseases) and lifespan.
Various nutritional interventions involving varying calorie and protein intake have been shown to improve the health and lifespan of rodents and primates. Furthermore, recent research has found a link between dietary macronutrients (proteins, carbohydrates, and fats) and cardiometabolic health and ageing in mice. However, the amount of protein needed to maintain metabolic health is unknown.
Protein requirements change throughout life, being higher in younger reproductive mice, decreasing through middle age, and rising again in older mice as protein efficiency declines.
Yoshitaka Kondo
In a new study published in GeroScience on a team of researchers led by Assistant Professor Yoshitaka Kondo from Waseda University, Japan, investigated the amount of dietary protein needed to improve metabolic health in mice approaching old age. The team, which also included Dr. Takuya Chiba, Faculty of Human Sciences, Waseda University, Dr. Akihito Ishigami, Molecular Regulation of Aging, Tokyo Metropolitan Institute for Geriatrics and Gerontology, Dr. Hitoshi Aoki, Research and Development Division, Nichirei Foods Inc, and Dr. Shin-Ichiro Takahashi, Department of Animal Sciences and Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo.
They enlisted the help of young (6-month-old) and middle-aged (16-month-old) male C57BL/6NCr mice, who were fed isocaloric diets with varying protein contents (5-45%) for two months. After two months, the effect of different protein diets was evaluated using skeletal muscle weight measurements, liver and plasma lipid profiles, and self-organizing map (SOM) cluster analysis of plasma amino acid profiles.
When asked about the study’s motivation, Kondo says, “The optimal balance of macronutrients for optimal health outcomes may vary across different life stages.” Previous research in mice suggests that changing the protein-to-carbohydrate ratio during old age can reduce age-specific mortality throughout life. However, the amount of protein that should be consumed to maintain metabolic health as we age remains unknown.”
The researchers discovered that consuming a low-protein diet resulted in the development of mild fatty liver, with higher levels of hepatic lipids in middle-aged mice compared to young mice. A moderate-protein diet, on the other hand, resulted in lower blood glucose concentrations and lipid levels in both the liver and the plasma. These results show that a moderate-protein diet (25% and 35%, respectively) kept both young and middle-aged mice metabolically healthier.
The researchers discovered that the plasma concentration of individual amino acids varied with age and dietary protein content when they investigated the effect of varying protein diets on plasma amino acid concentrations in mice of both ages. This was confirmed using SOM analysis of plasma amino acids. Furthermore, the plasma amino acid profiles revealed by SOM analysis demonstrated a link between different protein intake and varying levels of hepatic triglycerides and cholesterol.
“Protein requirements change throughout life, being higher in younger reproductive mice, decreasing through middle age, and rising again in older mice as protein efficiency declines,” Kondo says of their study’s impact on public health. Humans are likely to exhibit the same pattern. As a result, it could be assumed that increasing daily protein intake in meals could improve people’s metabolic health. Furthermore, optimal dietary macronutrient balance at each life stage may extend health span.”
Finally, a well-balanced diet rich in protein may be the key to living a long and healthy life.
