Much has been written about the importance of dietary protein for maintenance of muscle mass. But how many amongst us know how much protein we should be consuming, when to consume it or what source is best for us?
In Australia the current RDI (Recommended Daily Intake) for protein is around 0.8g per kilogram of bodyweight. However, several studies conclude that 1.2-1.5g/kg is a more appropriate target for older adults and a recent study carried out by the University of Arkansas for Medical Sciences¹ concludes that increasing this to around 1.8g/kg is needed to achieve maximal muscle.
So, for an individual weighing 70kgs that would mean a suggested daily protein intake of 126 grams. Compare that with Australian food labels which calculate a food’s protein contribution based on 50g of protein being 100% of RDI, as directed by the food regulator FSANZ. It’s easy to see why many think they are consuming adequate protein when this may not actually be the case.
What about timing of protein consumption? A study undertaken by researchers at the University of Texas² illustrated the significance of spreading intake evenly throughout the day, to achieve optimum muscle protein synthesis; say, 25-30g of protein at each mealtime. This may present quite a challenge to many, particularly at breakfast time which is often a carbohydrate-rich meal (e.g. cereal, toast)ᶟ.
The effectiveness of protein as we age is also impacted by its quality and our ability to digest it and thereby benefit from its muscle building properties. Animal proteins tend to be richer in the essential amino acid leucine, which is important for muscle protein synthesis. ‘Fast’ proteins such as whey in liquid form (e.g. a milk-based beverage) also tend to be easier to digest.
As our body’s ability to metabolise protein changes, we would be well-advised to carefully consider our dietary habits. Quality, quantity and timing of protein intake each appear to be important factors when considering how best to support healthy muscle as we age.