Effective translation of current dietary guidance: understanding and communicating the concepts of minimal and optimal levels of dietary protein.

Dietitians and health care providers have critical roles in the translation of the dietary guidance to practice. The protein content of diets for adults can be based on the Recommended Dietary Allowance (RDA) of 0.80 g/kg per day.

Optimal protein intake in the elderly.

The recommended dietary allowance (RDA) for protein, as promulgated by the Food and Nutrition Board of the United States National Academy of Science, is 0.8 g protein/kg body weight/day for adults, regardless of age. This value represents the minimum amount of protein required to avoid progressive loss of lean body mass in most individuals.

The effects of nutritional supplementation throughout an endurance run on leucine kinetics during recovery.

This study determined the effect of nutritional supplementation throughout endurance exercise on whole-body leucine kinetics (leucine rate of appearance [Ra], oxidation [Ox], and nonoxidative leucine disposal [NOLD]) during recovery. Five trained men underwent a 2-h run at 65% VO(2max), during which a carbohydrate (CHO), mixed protein-carbohydrate (milk), or placebo (PLA) drink was consumed. Leucine kinetics were assessed during recovery using a primed, continuous infusion of 1-13C leucine.

Leg glucose and protein metabolism during an acute bout of resistance exercise in humans.

The present study investigated the responses of leg glucose and protein metabolism during an acute bout of resistance exercise. Seven subjects (5 men, 2 women) were studied at rest and during a strenuous lower body resistance exercise regimen consisting of approximately 8 sets of 10 repetitions of leg press at approximately 75% 1 repetition maximum and 8 sets of 8 repetitions of knee extensions at approximately 80% 1 repetition maximum. L-[ring-2H5]phenylalanine was infused throughout the study for measurement of phenylalanine rates of appearance, disappearance, protein synthesis, and protein breakdown across the leg.

Dietary calcium and dairy modulation of adiposity and obesity risk.

Dietary calcium plays a key role in the regulation of energy metabolism and obesity risk. This appears to be mediated primarily by dietary calcium modulation of circulating calcitriol, which in turn regulates adipocyte intracellular calcium ([Ca2+]i). Increased [Ca2+]i stimulates lipogenic gene expression and activity and inhibits lipolysis, resulting in increased adipocyte lipid accumulation.

Exogenous nitric oxide increases basal leg glucose uptake in humans.

This study addressed the role of blood flow and nitric oxide in leg glucose uptake. Seven subjects (5 men, 2 women) were studied during conditions of resting blood flow and increased blood flow, achieved by infusion of the nitric oxide (NO) donor sodium nitroprusside (SNP) into the femoral artery. Femoral arterial and venous blood samples were obtained and blood flow was determined by infusion of indocyanine green dye.

Independent and combined effects of amino acids and glucose after resistance exercise.

Purpose: This study was designed to assess the independent and combined effects of a dose of amino acids (approximately 6 g) and/or carbohydrate (approximately 35 g) consumed at 1 and 2 h after resistance exercise on muscle protein metabolism.

Methods: Following initiation of a primed constant infusion of H -phenylalanine and N-urea, volunteers performed leg resistance exercise and then ingested one of three drinks (amino acids (AA), carbohydrate (CHO), or AA and CHO (MIX)) at 1- and 2-h postexercise.(5)

Results: Total net uptake of phenylalanine across the leg over 3 h was greatest in response to MIX and least in CHO.

Metabolic response to provision of mixed protein-carbohydrate supplementation during endurance exercise.

The interaction of substrates and hormones in response to ingestion of intact proteins during endurance exercise is unknown. This study characterized substrate and hormone responses to supplementation during endurance exercise. Nine male runners participated in 3 trials in which a non-fat (MILK), carbohydrate (CHO), or placebo (PLA) drink was consumed during a 2-hour treadmill run at 65% VO2max.