Dietary Protein Requirement Threshold and Micronutrients Profile in Healthy Older Women Based on Relative Skeletal Muscle Mass.

Praval Khanal,Martine Thomis,Hans Degens,Christopher I Morse,Georgina K Stebbings,Alun G Williams,Gladys L Onambele-Pearson,Lingxiao He

doi:10.3390/nu13093076

Abstract

Although multiple nutrients have shown protective effects with regard to preserving muscle function, the recommended amount of dietary protein and other nutrients profile on older adults for maintenance of high muscle mass is still debatable. The aims of this paper were to: (1) identify dietary differences between older women with low and high relative skeletal muscle mass, and (2) identify the minimal dietary protein intake associated with high relative skeletal muscle mass and test the threshold ability to determine an association with skeletal muscle phenotypes. Older women (n = 281; 70 ± 7 years, 65 ± 14 kg), with both low and high relative skeletal muscle mass groups, completed a food questionnaire. Skeletal muscle mass, fat-free mass (FFM), biceps brachii thickness, vastus lateralis anatomical cross-sectional area (VLACSA), handgrip strength (HGS), maximum elbow flexion torque (MVCEF), maximum knee extension torque (MVCKE), muscle quality (HGS/Body mass), and fat mass were measured. Older women with low relative skeletal muscle mass had a lower daily intake of protein, iodine, polyunsaturated fatty acid (PUFA), Vit E, manganese, milk, fish, nuts and seeds (p < 0.05) compared to women with high relative skeletal muscle mass. The minimum required dietary protein intake for high relative skeletal muscle mass was 1.17 g/kg body mass/day (g/kg/d) (sensitivity: 0.68; specificity: 0.62). Women consuming ≥1.17 g/kg/d had a lower BMI (B = −3.9, p < 0.001) and fat mass (B = −7.8, p < 0.001), and a higher muscle quality (B = 0.06, p < 0.001). The data indicate that to maintain muscle mass and function, older women should consume ≥1.17 g/kg/d dietary protein, through a varied diet including milk, fish and nuts that also contain polyunsaturated fatty acid (PUFA) and micronutrients such as iodine, Vit E and manganese.

Highlights

One of the factors contributing to age-related skeletal muscle degeneration is poor nutrient intake [1]
Some studies report that a protein intake between 1.0–1.2 g/kg/d is appropriate for musculoskeletal health [8,9,10], while others recommend >1.2 g/kg/d to combat sarcopenia [11,12] and the British Nutrition Foundation (BNF) even suggested that the recommended daily allowance (RDA) for the older adults is as low as 0.75 g/kg/d [13]
The current study identified a threshold of 1.17 g/kg/d protein required for the maintenance of high Relative skeletal muscle mass (SMMr), where consuming more protein than this threshold was associated with lower Body mass index (BMI), lower fat mass, and higher muscle quality in older women

Summary

Introduction

One of the factors contributing to age-related skeletal muscle degeneration is poor nutrient intake [1]. In extreme conditions, such as anorexia of ageing, inadequate food intake has been associated with impaired physical performance and an increased risk of disability among older community-dwellers [2]. Despite the beneficial effect of protein intake on protein synthesis, the minimum recommended daily allowance (RDA) of 0.8 g/kg body mass/day (g/kg/d) for an older person is still a matter of debate [7]. Some studies report that a protein intake between 1.0–1.2 g/kg/d is appropriate for musculoskeletal health [8,9,10], while others recommend >1.2 g/kg/d to combat sarcopenia [11,12] and the British Nutrition Foundation (BNF) even suggested that the RDA for the older adults is as low as 0.75 g/kg/d [13]

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Conclusion