Article - Muscle Mass Changes After Daily Consumption of Protein Mix Supplemented With Vitamin D in Adults Over 50 Years of Age: Subgroup Analysis According to the Serum 25(OH)D Levels of a Randomized Controlled Trial.

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Take home message

Consider supplementing protein in combination with leucine, vitamin D and calcium in middle-aged or older adults with insufficient vitamin D levels for prevention of sarcopenia.

Evidence category

A: Meta-analyses, position-stands, randomized-controlled trials (RCTs)

Summary review

Introduction

Sarcopenia increases the risk of falls and death
Protein and vitamin D are important for maintaining muscle mass whilst leucine is involved in regulating muscle protein turnover
The aim of this study was to evaluate the effects of a supplement containing protein, vitamin D, leucine and calcium on muscle mass, physical functioning, muscle strength, and physical ability in middle-aged and older adults.

Methods

Double-blind, randomised, placebo-controlled trial, with a duration of 12 weeks. Included 120 healthy Koreans aged 50-80 years
Participants were assigned to “insufficient” subgroup if vitamin D levels were <30ng/ml and to the “sufficient” subgroup if vitamin D was 30ng/ml or higher
Intervention: 2.5g powder (containing 20g protein (90% milk/10% soya, incl. 3g leucine), 800 IU vitamin D, 300 mg calcium) mixed into beverage of choice twice a day. Control: isocaloric placebo powder
Primary outcome: Muscle mass determined by dual-energy X-ray absorptiometry (DXA) and bioelectrical impedance analysis (BIA)
Secondary outcomes: Muscle strength (femoral muscle and grip strength); physical functioning (short physical performance battery (SPPB), International Physical Activity Questionnaire (IPAQ)).

Results

At baseline, age of participants in the “sufficient” intervention subgroup was higher than that of the “sufficient” control subgroup (p=0.02)
Increase in vitamin D levels in intervention group relative to control group, in both sufficient and insufficient subgroups (difference in changes between groups 11.5 ng/ml and 13.9 ng/ml, respectively, both p=0.00)
No difference in change in muscle index as measured by DXA between groups
In the “insufficient” subgroup, BIA increases in muscle mass were seen when normalised by height (p=0.037) and weight (p=0.05)
No differences in changes in physical functioning or muscle strength between groups.

Conclusion

The authors conclude that a supplement containing protein, with high levels of leucine, vitamin D and calcium may be of benefit for muscle mass to middle-aged and older adults with insufficient vitamin D levels.

Clinical practice applications

Middle-aged and older adults with insufficient vitamin D levels may gain muscle mass through supplementation of protein, leucine, vitamin D and calcium
Middle-age and older adults with sufficient vitamin D levels do not appear to benefit from the same intervention.

Considerations for future research

Longer-term studies may help identify whether increases in muscle mass lead to improved physical functioning over time
A study combining supplementation and exercise may help identify additive or synergistic effects.

Abstract

UNLABELLED

Early prevention of sarcopenia can be an important strategy for muscle maintenance, but most studies target subjects at slightly pre-sarcopenic state. Our previous paper describes the effect of protein supplements rich in leucine and vitamin D on muscle condition, and in this paper, we performed a sub-analysis to evaluate who benefitted the most in terms of improvement in muscle health. A 12-week randomized clinical trial of 120 healthy adults (aged 50 to 80) assigned to an intervention group (n = 60) or control group (n = 60) were analyzed. Subjects in the intervention group received, twice per day, a protein supplement containing (per serving) 800 IU of vitamin D, 20 g of protein (3 g of total leucine), 300 mg of calcium, 1.1 g of fat, and 2.5 g of carbohydrate. The subjects were classified into 'insufficient' and 'sufficient' groups at 25-hydroxyvitamin D (25[OH]D) value of 30 ng/mL. The skeletal muscle mass index normalized to the square of the skeletal muscle mass (SMM) height (kg/m) increased significantly in the 'insufficient group' difference value of change between weeks 0 and 12 (Δ1.07 ± 2.20; p = 0.037). The SMM normalized by body weight (kg/kg, %) was higher, but not significantly, in the insufficient group (Δ0.38 ± 0.69; p = 0.050). For people with insufficient (serum 25[OH]D), supplemental intake of protein and vitamin D, calcium, and leucine and adequate energy intake increases muscle mass in middle-aged and older adults and would be likely to exert a beneficial effect on muscle health.

TRIAL REGISTRATION

Clinical Research Information Service Identifier: KCT0005111.