Making muscle-targeted nutrition the first-line in frailty

Sarcopenia, a prevalent disease in ageing populations globally, involves the involuntary loss of skeletal muscle mass and strength and puts populations at greater risk of hospital readmission, mortality, falls, and fractures.

Speaking during the Nutricia Global Virtual Conference 2023​, Luc Van Loon, Professor of Exercise and Nutrition at Maastricht University in The Netherlands, explained skeletal muscle tissue is constantly synthesised and broken down.

“Muscle actually turns over at a rate of 1-2% per day meaning that within 50-100 days you can fully recondition your muscle.”

Whilst this is beneficial for muscle building, it also means we are susceptible to muscle loss at times of reduced muscle use.

In fact, Prof Van Loon revealed that during times of hospitalisation, just 5-7 days immobilised can lead to 1.4kg of muscle mass.

He explained that from the nutrition point of view, it’s the protein in our diets that provides amino acids - the building blocks of skeletal muscle tissue and signalling molecules that lead to protein synthesis.

"So simply ingesting protein will strongly elevate muscle protein synthesis for up to about five hours after a meal... The amino acids you ingest even appear in your muscle protein within two hours after eating a meal.

“So your mum was always right – you are what you just ate.”

However he noted many factors impact post-meal muscle synthesis, including the source of protein, timing, macronutrients, and food preparation.

Two of the most important factors that determine the anabolic properties of a protein are the rate at which the protein is digested and absorbed, and the composition of the amino acids, most notably leucine.

In terms of ‘anabolic stimulus’ of muscle protein, Prof Van Loon explained that muscle contraction stimulates muscle protein synthesis for up to 24 hours after exercise.

But he added that “physical activity makes the muscle more sensitive to the anabolic properties of protein ingestion.”

“So you are what you eat, but if you are physically active prior to food intake you become more of what you just ate.”

He noted that whilst this is an understanding widely implemented within athletes, it’s something which should be more widely utilised in ageing and hospitalised populations.

Age-related muscle loss is largely explained by the reduced sensitivity to the anabolic properties of food, he explained, adding that many studies have shown the anabolic response to amino acids in elderly people is much lower than in younger people.

One of the most significant explanations for this anabolic resistance is decline in activity.

“The good news is that exercise training in the elderly can increase muscle mass, endurance and functional capacity. However, we need to combine the right amount of exercise and nutrition.”

The professor noted that it is often visits to hospital that add to the longer term muscle loss in the elderly, as it is never fully regained.

He said it is within the hospital setting then, that protein is of the utmost importance.

Dr Emanuele Cereda, physician and research scientist at the Clinical Nutrition and Dietetics Unit of the Fondazione IRCCS Policlinico, Italy, joined the discussion with a call for action to optimise nutritional care for hospital patients.

He noted that surveys have revealed that elderly residents in care settings frequently have a protein intake below recommended amounts.

He argued it is important to consider the use of nutritional supplements at the beginning of intervention as a norm.

Dr Cereda conducted research, published in ‘Nutrients’ in 2022, which revealed whey protein supplementation, alongside leucine and vitamin D, is a ‘really powerful intervention’ in sarcopenia patients for improving physical function and muscle mass.

He added that it is important to intervene before the loss of muscle mass (pre-sarcopenia) by addressing physical functional and performance, as opposed to analysing actual muscle mass.

What's more, he advised there are certain populations that should be reasonably considered at nutritional risk, such as those over 70 and suffering with a disease, without a need for nutritional assessment.

He concluded: “Be more assertive. Don’t waste time screening and think about the treatment early.”

Joining to discuss the personal barriers to protein supplementation, Laure Verstraeten, lead author of the EMPOWER-GR​ (n=200) observational study of geriatric rehabilitation patients, discussed her survey of patients in which they were asked about their willingness to undergo treatment for sarcopenia.

They found that whilst 60% said they would be happy to take protein supplements, several voiced a dislike of oral nutritional supplements and several discussed doubts over the effectiveness of treatment. This reveals areas for innovation and education.