Milk vs. Soy Proteins

HAMILTON, OntarioMilk-based proteins increase muscle to a greater extent than do soy-based proteins when consumed after resistance exercise, according to researchers at McMaster University here. Researchers examined the effect of consuming isonitrogenous, isoenergetic and macronutrient-matched soy or milk beverages on protein kinetics and net muscle protein balance after resistance exercise in healthy young men. In the crossover trial, arterial-venous amino acid balance and muscle fractional synthesis rates were measured in young men who consumed fluid milk or a soy-protein beverage after a bout of resistance exercise. Researchers found ingestion of both soy and milk resulted in a positive net protein balance, however, analysis indicated an overall greater net balance after milk ingestion (P < 0.05). The fractional synthesis rate in muscle was also greater after milk consumption (0.10 ± 0.01 percent/h) than after soy consumption (0.07 ± 0.01 percent/h; P = 0.05). Researchers concluded consumption of milk orsoy protein with resistance training promotes muscle mass maintenanceand gains, but chronic consumption of milk proteins after resistanceexercise likely supports a more rapid accrual of lean mass. The study was published in the American Journal of Clinical Nutrition (85, 4: 1031-1040, 2007).