A recent study(1) of 120 elderly people aged 70-85y has demonstrated that supplementing a diet with adequate amounts of the right kind of protein supplement can have measurable benefits in muscle mass and performance, even in the absence of resistance exercise.
What form of high quality protein was recommended in they study? Let's take a closer look.
First, it's important to note that this is a single study and the subjects were screened as pre-frail or frail, however it's a randomised, double-blind, placebo-controlled 12-week intervention trial published in the American Journal of Clinical Nutrition and adds to the emerging consensus that:
"consuming an adequate amount of high-quality protein at each meal, in combination with physical activity, may delay the onset of sarcopenia, slow its progression, reduce the magnitude of its functional consequences, or all of these."(2)
Protein and resistance exercise seem to have a synergistic benefit, but would these participants see a similar benefit in the absence of additional exercise?
Over a 12-week period, subjects were randomly allocated to one of three groups and asked to maintain their normal diet and physical activity. The groups were provided with either a control of maltodextrin or whey protein supplements representing 0.8g, 1.2g, or 1.5g protein per kg body weight per day.
What was the outcome?
Those in the higher dose group, equivalent to a 60kg person consuming 90g protein per day, improved both appendicular muscle mass (measured as total muscle mass on the arms and legs) and skeletal muscle index adjusted for height, weight, BMI and as a ratio to body fat. Also, those in the higher dose group showed improved performance, measured as gait speed (or walking speed).
This outcome agrees with an earlier studies (3.4), in which lean body mass was preserved with higher doses of whey protein for older compared to younger subjects.
However other studies using milk protein, hydrolysed milk or cheese showed no significant beneficial effects for the older population. The authors suggested two possible reasons.
One seems to be the higher amount of leucine present in whey protein. Earlier studies and meta-analyses concluded that:
"...whey protein was best to support muscle protein synthesis owing to its high leucine content compared with milk and soy protein." (5)
Participants in the high dose group in the present study consumed around 4.3g leucine per day, a similar dose to the amount present in Muscle Maintenance 70+ when served with full cream milk.
The other reason suggested was that:
"increased deviation from normal protein intake...could affect gains of muscle mass."(1)
All up, the study showed that:
"...pre-frail and frail elderly subjects at risk of malnutrition experienced improvement in some aspects of physical performance...beyond the significant gain in muscle mass after consumption of 1.5g protein per kg per day compared to with consumption of 0.8g protein per kg per day." (1)