Marine n-3 Polyunsaturated Fatty Acids

A Potential Role in the Treatment of Sarcopenia

Stuart Gray; Mariasole Da Boit

Disclosures

Clin Lipidology. 2013;8(2):187-194. 

In This Article

Abstract and Introduction

Abstract

Sarcopenia is the age-related loss of muscle mass that results in a reduction in skeletal muscle function, quality of life and an increased risk of falls. Older muscle has an 'anabolic resistance' to both nutrients and exercise, with the precise underlying mechanism still to be elucidated. The n-3 polyunsaturated fatty acids found in fish oil can be incorporated into the membranes of skeletal muscles, where they may have anti-inflammatory effects. This alteration in muscle membrane fatty acid composition may have anabolic effects in aging muscle and, thus, be useful in the treatment of sarcopenia.

Introduction

Aging is associated with numerous clinical problems, such as arthritis, cardiovascular disease, hypertension and Alzheimer's disease, among others. On top of this association with disease, dramatic changes in body composition also occur, with the loss of skeletal muscle mass being the major alteration consistently observed. This loss in skeletal muscle has been termed sarcopenia, from the Greek words for flesh (sarx) and loss (penia),[1] and occurs even in healthy, active older individuals at a rate of approximately 0.5–2.0% loss in muscle mass per year.[2] There is a reported incidence of sarcopenia of 13–24% in those aged 50–70 years and up to 50% in those over 80 years of age.[2] Accurate reporting of these figures can be problematic as the diagnosis of sarcopenia is not straightforward, with several criteria employed within the literature (e.g., an appendicular lean mass of two standard deviations or greater below the mean of a young reference group).[2] In recent years, the European Working Group on sarcopenia in older people have suggested a diagnosis algorithm based upon low levels of gait speed, grip strength and muscle mass, although this still remains a contentious issue.[3]

As skeletal muscle is required for activities of everyday life, for example, stepping onto a bus, rising from a chair, putting on a jacket and walking even short distances, we therefore see substantial impairments in muscle strength and functional abilities in this condition. This can reduce older adults' quality of life and increase the risk of falls and subsequent hospitalization.[4] This occurs alongside a substantial economic cost, estimated to cost US$18.5 billion in the USA in the year 2000.[5] Interestingly, the loss in muscle strength occurs at a greater rate than the loss in muscle size.[6] The reason behind this divergence between strength and size may have numerous causes, such as ectopic fat deposition within skeletal muscle,[7] motor unit remodeling[8] and/or changes in the intrinsic contractile properties of the myofibers themselves.[9] Taken together, it is easy to see why methods to treat sarcopenia, as well as research to further our understanding of the mechanisms underlying sarcopenia, are of clear importance.

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