L-Carnitine Supplementation in Older Women. A Pilot Study on Aging Skeletal Muscle Mass and Function.

Angelika Sawicka,Robert Olek,Wieslawa Lysiak-Szydlowska,Dace Hartmane,Ewa Wojtowicz,Patrycja Lipinska

doi:10.3390/nu10020255

Abstract

Skeletal muscle wasting, associated with aging, may be regulated by the inflammatory cytokines as well as by insulin-like growth factor 1 (IGF-1). l-carnitine possesses anti-inflammatory properties and increases plasma IGF-1 concentration, leading to the regulation of the genes responsible for protein catabolism and anabolism. The purpose of the present study was to evaluate the effect of a 24-week l-carnitine supplementation on serum inflammatory markers, IGF-1, body composition and skeletal muscle strength in healthy human subjects over 65 years of age. Women between 65 and 70 years of age were supplemented for 24 weeks with either 1500 mg l-carnitine-l-tartrate or an isonitrogenous placebo per day in a double-blind fashion. Before and after the supplementation protocol, body mass and composition, as well as knee extensor and flexor muscle strength were determined. In the blood samples, free carnitine, interleukin-6, tumor necrosis factor-α, C-reactive protein and IGF-1 were determined. A marked increase in free plasma carnitine concentration was observed due to l-carnitine supplementation. No substantial changes in other parameters were noted. In the current study, supplementation for 24 weeks affected neither the skeletal muscle strength nor circulating markers in healthy women over 65 years of age. Positive and negative aspects of l-carnitine supplementation need to be clarified.

Highlights

Aging is accompanied by a progressive change in the ratio between fat and lean body mass (BM).Fat mass, in particular visceral adipose tissue, increases, whereas fat free mass (FFM) declines [1].Adipose tissue itself produces and releases a number of cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and other bioactive molecules [2]
A body of literature has demonstrated that inflammatory cytokines activate many of the molecular pathways involved in skeletal muscle wasting, leading to an imbalance between protein synthesis and degradation [4,5]
We have evaluated the effect of L-carnitine supplementation on muscle mass, strength, and selected blood markers in older women at risk for sarcopenia

Summary

Introduction

Aging is accompanied by a progressive change in the ratio between fat and lean body mass (BM).Fat mass, in particular visceral adipose tissue, increases, whereas fat free mass (FFM) declines [1].Adipose tissue itself produces and releases a number of cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and other bioactive molecules [2]. Aging is accompanied by a progressive change in the ratio between fat and lean body mass (BM). In particular visceral adipose tissue, increases, whereas fat free mass (FFM) declines [1]. Adipose tissue itself produces and releases a number of cytokines, such as interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and other bioactive molecules [2]. Even healthy aging results in slight elevations of circulating proinflammatory mediators, corresponding to a chronic low-grade inflammatory profile [3]. A body of literature has demonstrated that inflammatory cytokines activate many of the molecular pathways involved in skeletal muscle wasting, leading to an imbalance between protein synthesis and degradation [4,5]. High doses of TNF-α lead to reduced muscle cell differentiation in human and mouse muscle cells [6,7] and cause myotube (in vitro) and myofibre (in vivo) atrophy in animals [8,9], Nutrients 2018, 10, 255; doi:10.3390/nu10020255 www.mdpi.com/journal/nutrients

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