Omega-3 fatty acids and vitamin D in immobilisation: Part A- Modulation of appendicular mass content, composition and structure

Bostock, EL ORCID: https://orcid.org/0000-0001-9340-8459, Morse, CI, Winwood, K ORCID: https://orcid.org/0000-0002-8696-9976, McEwan, I ORCID: https://orcid.org/0000-0001-8036-0505 and Onambele-Pearson, GL (2017) Omega-3 fatty acids and vitamin D in immobilisation: Part A- Modulation of appendicular mass content, composition and structure. Journal of Nutrition, Health and Aging, 21 (1). pp. 51-58. ISSN 1279-7707

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Abstract

Objectives: Muscle size decreases in response to short-term limb immobilisation. This study set out to determine whether two potential protein-sparing modulators (eicosapentaenoic acid and vitamin D) would attenuate immobilisation-induced changes in muscle characteristics. Design: The study used a randomised, double-blind, placebo-controlled design. Setting: The study took part in a laboratory setting. Participants: Twenty-four male and female healthy participants, aged 23.0±5.8 years. Intervention: The non-dominant arm was immobilised in a sling for a period of nine waking hours a day over two continuous weeks. Participants were randomly assigned to one of three groups: placebo (n=8, Lecithin, 2400 mg daily), omega-3 (-3) fatty acids (n=8, eicosapentaenoic acid (EPA); 1770 mg, and docosahexaenoic acid (DHA); 390 mg DHA, daily) or vitamin D (n=8, 1,000 IU daily). Measurements: Muscle and sub-cutaneous adipose thickness (B-mode ultrasonography), body composition (DXA), arm girth (anthropometry) were measured before immobilisation, immediately on removal of the sling and two weeks after re-mobilisation. Results: Muscle thickness (-5.4±4.3%), upper and lower arm girth (-1.3±0.4 and -0.8±0.8%, respectively), lean mass (-3.6±3.7%) and bone mineral content (BMC) (-2.3±1.5%) decreased significantly with limb immobilisation in the placebo group (P<0.05). Despite no significant effect of group, -3 and vitamin D supplementation showed trends (p>0.05) towards attenuating the decreases in muscle thickness, upper/lower arm girths and BMC observed in the placebo group. The -3 supplementation group demonstrated a non-significant attenuation of the decrease in DXA quantified lean mass observed in the placebo group. Sub-cutaneous adipose thickness increased in the placebo group (P<0.05). -3 and vitamin D both blunted this response, with -3 having a greater effect (P<0.05). All parameters had returned to baseline values at the re-mobilisation phase of the study. Conclusion: Overall, at the current doses, -3 and vitamin D supplementation only attenuated one of the changes associated with non-injurious limb immobilisation. These findings would necessitate further research into either a) supplementation linked to injury-induced immobilisation, or b) larger doses of these supplements to confirm/refute the physiological reserve potential of the two supplements. Keywords: Docosahexaenoic Acid; Eicosapentaenoic Acid; Immobilisation; Lecithin; Omega 3; Vitamin D.