Lessons from animal nutritionists: dietary amino acid requirement studies and considerations for healthy aging studies

Abstract

Dietary restriction (DR) increases median life span and protects against age-related disease. Improved longevity can be achieved by restriction of dietary energy, protein, or amino acids (AAs), such as methionine (Met). Met requirements have been defined using methodologies that measure the dose response to Met when all other dietary variables are held constant and with outcomes focused on protein turnover. Here, we cover protein and sulfur AA requirements and discuss the terms "deficient," "optimal," and "excess" and how these need to be considered. We additionally discuss the effect of methyl-donating compounds on sulfur AA metabolism and outcomes. We will discuss how the mechanistic target of rapamycin complex 1 (mTORC1) signaling network regulates protein turnover, lipogenesis and cell growth, proliferation, differentiation, and metabolism in response to hormones, AAs, and cellular energy status. Inhibition of mTORC1 signaling with rapamycin or genetic mutation increases median life span in model organisms, and mTORC1 inhibition may be responsible for some of the life span-extending effects of DR. Finally, we discuss how the sulfur AAs may regulate aspects of reactive oxygen species (ROS) mitigation. Overall, we suggest that approaches evaluating AA intake need to consider whole-body protein synthesis and measures related to tissue-specific and whole-body metabolism that have been associated with longevity.

Ovarian activation delays in peripubertal ewe lambs infected with Haemonchus contortus can be avoided by supplementing protein in their diets

“…Excessive MTORC1 activation in older individuals is linked to chronic diseases like cancer, and the inhibition of MTORC1 increased life span. On the other side, its activation is necessary for young individuals for cell growth, proliferation, differentiation and metabolism in response to hormones leading to appropriate development [ 43 ].…”

Usefulness of Urinary Creatinine/Urea Nitrogen Ratio as Indicator of Body Protein Catabolism in Dogs Fed Low Protein Diets

“…However, the UCrn/UN ratio at 4 weeks was not higher than that at 0 weeks, indicating that body protein catabolism may have been suppressed by then. When protein is restricted, reduction of protein turnover is considered triggering an adaptation to protein restriction (50)(51)(52). In a study on canine protein catabolism in which healthy dogs were fed a 12% protein diet for 3 weeks, an examination of the kinetics of isotope-labeled leucine revealed decreases in both body protein synthesis and breakdown (53).…”

Expression of Multicopy Tandem Recombinant Ginseng Hexapeptide in Bacillus subtilis and the Evaluation of Antiaging Activity

“…In addition, these bioactive peptides can reduce oxidative stress and age-related diseases by eliminating excess radicals in the body . In this regard, an antioxidant diet can be effective in preventing oxidative stress-induced cell aging. − Damage caused by oxidative stress can accelerate cellular senescence, in which high levels of reactive oxygen species (ROS) are a major factor in disrupting the body’s antioxidant system. , Therefore, enhancing the antioxidant capacity is an effective way to delay aging. In addition, the other two methods are senolytic therapy and senomorphic therapy.…”