Protein & Amino Acids
topic
Protein provides the amino acids — 9 essential (cannot be synthesized by the human body: leucine, isoleucine, valine, lysine, methionine, phenylalanine, threonine, tryptophan, histidine) and 11 conditionally or non-essential — that are the structural and functional building blocks of every tissue, enzyme, hormone, antibody, and neurotransmitter in the body. Daily protein requirements for sedentary adults are approximately 0.8g/kg body weight, rising to 1.6–2.2g/kg for those doing resistance training, and higher for endurance athletes, older adults (who experience anabolic resistance), and people in recovery from illness or injury.
Role
Protein is the macronutrient most directly linked to body composition, satiety, and healthy aging — yet remains the most under-consumed by most people who are not actively bodybuilding, and simultaneously over-consumed as a cultural performance supplement by those who are. The consequences of protein insufficiency in aging populations are particularly severe: the muscle mass loss of sarcopenia (driven partly by insufficient protein intake and anabolic resistance) is one of the strongest predictors of functional decline, fall risk, metabolic disease, and mortality in older adults — making adequate protein intake a genuine longevity intervention that most older adults are not receiving.