Adaptation of protein metabolism in relation to limits to high dietary protein intake

Postprandial Thermogenesis Is Increased 100% on a High-Protein, Low-Fat Dietversusa High-Carbohydrate, Low-Fat Diet in Healthy, Young Women

“…Also, there is a net retention of amino acids in the body when dietary protein is increased, and nitrogen balance is positive, as high as ϩ7 to 13 gN/day [27,28], but more typically ϩ3 gN/day, even after the HP diet is consumed for an extended period [29]. The high positive nitrogen balance noted in the present trial likely represents a transient retention of nitrogen, either as urea or free amino acids such as glutamine in muscle tissue.…”

Impaired translation initiation activation and reduced protein synthesis in weaned piglets fed a low-protein diet

“…Recent findings indicate that concentrations of amino acids in plasma were positively correlated with protein synthesis in neonatal pigs [28,30]. Therefore, the reduction in protein synthesis rate may be a necessary part of the metabolic adaptation to chronic protein insufficiency, therefore ensuring minimal nitrogen excretion and maximum utilization of dietary protein [31]. This would allow the organism to maintain a nitrogen balance and survive.…”

Limits of adaptation to high dietary protein intakes

“…The implicit assumption in discussing the response to high levels of protein intake is that higher than usual intakes may confer some bene®t. In approaching the question Peter Garlick has provided a very helpful overview and in my opinion developed a fairly convincing argument that there is no evidence for bene®t being conferred simply by increasing the protein intake to a high level (Garlick et al, 1999). The approach adopted asks whether it is possible to drive the body to improved function, or to determine adverse effects or gross pathology using whole body measures when comparing higher levels of protein intake with habitual intakes.…”