Impact of non-protein nutrients underestimated in muscle regulation, review finds

Writing in the Journal of Physiology​, Canadian researchers identify non‐protein nutrients such as omega-3 fatty acid supplementation as capable of modulating the muscle protein synthesis (MPS) response upon ingestion.

“Omega-3 fatty acids represent a promising area of research for the development of nutritional strategies to counteract anabolic resistance in older adults,”​ the review commented.

“The next logical step would be to investigate whether ingestion of fatty acids such as omega-3s can offset skeletal muscle atrophy during periods of bed rest/muscle disuse in ageing persons.” ​

Such research would have an important clinical impact, particularly amongst older adults and associated periods of muscle disuse during an extended hospital stay.

The review also has much significance in the focus of obtaining a range of nutrients in food rather than focusing on protein/amino acids alone, which may affect daily protein requirements, particularly in older individuals.

Insightful review paper from Stuart Phillips' lab on the role of nutrition in muscle growth. Particularly intriguing is the potential for other nutrients besides amino acids to regulate hypertrophy https://t.co/3soVY2e50Ypic.twitter.com/uW5NQLhFA8

— Brad Schoenfeld, PhD (@BradSchoenfeld) July 19, 2018

Omega-3 emphasis ​

The review reserved much of their focus on omega-3’s effect on MPS. The team mention a study that saw eight weeks of fish oil-derived omega-3 fatty acid supplementation increase the EPA and DHA content in skeletal muscle phospholipids and enhanced MPS in both older and younger adults.

In an extension to this work, another study supplemented healthy older adults with fish oil-derived omega-3 fatty acids, which was linked to increased skeletal muscle mass and function.

This report corroborated findings by other investigators who have shown that dietary supplementation with omega-3 fatty acids promotes gains in skeletal muscle strength during exercise training in older women.

“The biological mechanisms by which these fatty acids regulate skeletal muscle anabolism remain unknown,” ​the team said.

“Incorporation of the highly unsaturated fatty acids EPA and DHA into the diet has been associated with enhanced mechanistic target of rapamycin Q7 complex-1 signalling, which provides one potential mechanism. ​

“It is also possible that omega-3 fatty acid incorporation into skeletal muscle alters lipid raft formation and the transmission of mechanical and nutritional cues to the translational machinery.”​

A blend of nutrients  ​

Besides omega-3 supplementation, the review also makes a case for the provision of oleate, the vitamins A, D and E, and the minerals selenium and zinc, which in animal models, have shown direct influence in the muscle anabolic response.

To a lesser extent, the review also mentions bioactive compounds such as growth factors, peptides and miRNAs in coordinated changes in MPS and muscle protein breakdown (MPB).

“Current evidence would suggest that the presence of vitamins, minerals, lipids and other bioactive nutrients in food work in concert with amino acids/protein to support the postprandial rise in MPS,” the McMaster University team said. ​

“Elucidating the active biological non-protein components of food, such as specific lipid species, may yield important data relevant to the development of novel nutraceutical therapies to promote musculoskeletal health in older adults.”​

Age-associated loss of muscle loss and the loss of muscle caused by the numerous age-associated comorbidities are issues increasingly ageing populations have to address.

The process of ageing is said to reduce the size of muscles by around 0.5 and 2% a year. The process - sarcopenia - can result in a reduction in quality of life and loss of independence in many elderly people.

Sarcopenia affects 10–30% of independently living older adults without major illness, and is even more prevalent in those with chronic diseases and/or institutionalised older adults.

The negative health effects associated with sarcopenia have become such a worldwide health concern that it has recently been recognised as an independent condition having its own International Classification of Disease.

Source: Journal of Physiology​
Published online ahead of print: doi.org/10.1113/JP275443​​
“The impact of exercise and nutrition in the regulation of skeletal muscle mass.”​
Authors: Chris McGlory, Stephan van Vliet, Tanner Stokes, Bettina Mittendorfer, Stuart M. Phillips