It’s not a particularly welcome, but nevertheless unavoidable fact that, as people age, most lose muscle mass. This reduction, known in scientific and medical circles as ‘sarcopenia’, is observed to begin already around the age of fifty, and proceeds at a rate of up to two percent per year.
Why do we lose muscle mass? While there’s plenty of research both completed and ongoing in the field, there are just as many hypotheses around the actual mechanisms that underlie this phenomenon. It seems, in any case, that the sensitivity of muscle cells to respond anabolically to normal anabolic stimuli (primarily nutrition and the person’s use of their muscles) decreases in the ageing body.
The constant breakdown and buildup cycle of proteins in the muscle is known as ‘protein turnover’. This phenomenon covers two kinetic processes: protein synthesis and breakdown, which together determine the net protein balance and thus, whether proteins are gained or lost.
Studies reveal that, in older populations, the synthesis part of this process doesn’t function as effectively – at least in response to the repeated daily anabolic stimuli exerted by meals and daily physical activities (older people do appear to maintain the same basal resting state turnover rate as younger ones).
At the same time, there is a tendency toward comorbidities as the population ages. These and other physiological changes have an impact on muscle mass deterioration, too, but age in itself is a significant factor causing this deterioration of the muscles.
What can be done?
So what, if anything, can be done to prevent or slow down the sarcopenic process, which is the repeated inability to obtain a zero or positive protein balance during daily living? Basically, the idea is to ensure muscle turnover is stimulated on a daily basis, ensuring that protein synthesis exceeds breakdown rates. And that means, based on our current understanding, performing specific types of exercise, adding more protein to the diet, paying attention to how protein-containing foods are ingested throughout the day, and by undergoing pharmacological treatments that address, for example, inflammatory states that can impair anabolic responses.
To date, there is no magic pill that resets the clock, restoring our muscle turnover process to its former glory – and, at this stage, such a remedy is hardly on the horizon. But a great deal of research is going on to combat sarcopenia, including work being undertaken here at Birmingham University. And some day, we will find out what really works. I’m quite sure of that.
Whey protein’s role
One of the items mentioned in my list above concerns the intake of protein through the diet. Over the past two or three decades, numerous studies have been carried out to examine the role and effect of different sources of protein. Among these, dairy proteins have figured extensively, largely due to the dairy industry’s sponsorship of the research endeavours. As a result, we know comparatively much about dairy proteins, and about whey protein, in particular.
When contemplating the role of protein-heavy foods and protein supplements in the diet, what really matters is two things: One is the content of the necessary essential amino acids, the other is the speed and efficiency with which these can be digested, and taken up and made available in the circulation. Whey-based amino acids are taken up quickly, bringing high spikes in concentrations that are a special feature of whey (other protein sources must be hydrolyzed, i.e. chopped up until smaller peptides, to match the strength of this effect).
That sounds good, of course, but there’s a catch. And this is something our own labs are examining with great interest: If you add whey protein into a food matrix, the matrix will delay the uptake of the amino acids to some extent, affecting the protein’s ability to stimulate anabolic muscle activity. Put more simply, if you eat whey protein together with other foods, you don’t get the full, fast-acting uptake and appearance of the amino acids in the blood. Whether this impacts the protein’s impact on the build-up effect on the muscles is currently subject to investigations.
What about exercise?
Then there’s exercise. Exercise is a remedy irrespective of age – and there are well-documented benefits of adding protein during periods where people exercise to gain muscle. It’s a conclusion reached in studies of both young and older populations, and in meta-analyses of the existing body of research.
In my opinion, however, it’s not a matter of being able to answer yes or no to the question “is there an anabolic benefit of taking protein supplements alone or in combination with exercise?”. That’s because it very much depends on how much protein you consume in your normal diet, as well as how much your body is able to utilise.
Clearly, if your normal diet contains plenty of protein, adding more may not make much of a difference. That said, there are research reports that show, at least in some cases, adding protein to the diet alone can contribute to gaining some degree of muscle mass. Other studies, however, have failed to demonstrate this effect.
The short answer, I believe, is that some people with ‘too low’ intake of protein can gain mass via enhancing protein intake alone, but it may not work for all. It depends on the window – i.e., the gap between what your body needs and how much protein your diet contains. In younger people, this window is typically non-existent because most will consume plenty for their needs. Paradoxically, however, older people seem to need more protein as they age, yet consume less, perhaps due to reducing appetite or limited food choices. Their window, therefore, is usually far wider and they stand to reap greater benefit.
Focus on the individual
It’s also worth mentioning that the vast majority of studies conducted, and the conclusions they reach, are based on populations rather than on the profiles and physiological responses of individuals. So, at an individual level, there can be wide variation in responses to protein-based interventions. So far, these variations are unexplained, and may be due to physiological factors, analytical variation or some combination of parameters. Ideally, of course, we should, one day, be able to prescribe individualized supplements, treatments and medications based on a more complete understanding of these factors and their implications for individuals.
Where to next?
Where are the priorities for our research in this field in the years to come? We’re concentrating our efforts on the interaction between proteins and the food matrix, and on the distribution of protein intake throughout the day. The latter is of interest because we believe it is important both to be able to obtain peaks at certain points and to have enough protein readily available at any given time. All this translates into a certain amount of protein per meal – but the question remains, which levels are appropriate for breakfast, lunch or dinner, for example? Current insights point to protein levels being too low at breakfast and lunch, but we don’t have enough data on the impact of this pattern.
We also need to more closely explore new ways to take in sufficient protein for different patient profiles. In fact, it appears already that the amounts required for optimally addressing sarcopenia may not be possible to ingest. Years from now, therefore, we expect to see more products that are enriched with whey protein or hydrolysates of other protein sources, adding protein into the foods people like to eat or which they tend to eat most of rather than normal, protein-heavy food types.
Getting it right
It’s all about working with the right type of protein and limiting the total amount ingested to what the body actually needs rather than consistently reaching excess levels. And objectively speaking, whey protein, with its characteristics, shows great promise as a commercially available protein that can help us with solutions to address such issues in the future.
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