Abstract
Purpose: The aim was to investigate the cross-sectional association of dietary omega-3 polyunsaturated fatty acids PUFA (alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA)) intake with multiple physical functions, muscle mass and fat mass in older women.
Method:Study subjects were 554 women from the Osteoporosis Risk Factor and Prevention Fracture Prevention Study, with dietary intake assessed with 3-day food record. Body composition was measured by dual-energy X-ray absorptiometry. Physical function measures included walking speed 10 m, chair rises, one leg stance, knee extension, handgrip strength and squat. Short physical performance battery (SPPB) score was defined based on the European working group on sarcopenia criteria.
Results: The multivariable adjusted models showed statistically significant associations for dietary ALA with higher SPPB (β = 0.118, P = 0.024), knee extension force at baseline (β = 0.075, P = 0.037) and lower fat mass (β = – 0.081, P = 0.034), as well as longer one-leg stance (β = 0.119, P = 0.010), higher walking speed (β = 0.113, P = 0.047), and ability to squat to the ground (β = 0.110, P = 0.027) at baseline. Total dietary omega-3 PUFA was associated with better SPPB (β = 0.108, P = 0.039), one-leg stance (β = 0.102, P = 0.041) and ability to squat (β = 0.110, P = 0.028), and with walking speed (β = 0.110, P = 0.028). However, associations for dietary EPA and DHA with physical function and body composition were not significant. Conclusion: Dietary omega-3 and ALA, but not EPA and DHA, were positively associated with muscle strength and function in older women. The intake of omega-3 and its subtypes was not associated with muscle mass. Longitudinal studies are needed to show whether omega-3 intake may be important for muscle function in older women.
Link to Full Text
Key Points
Ageing is associated with progressive physical function loss, changes in body composition by increase in fat mass and loss of muscle mass. Observational studies provided evidence on the positive association between plasma phospholipid PUFAs with knee extension and muscle mass, total omega-3, DHA, EPA and ALA intakes were positively associated with peak force (all individuals and men). Most previous studies used single muscle strength outcomes, whereas the current study provides further evidence by studying the association for omega-3 PUFAs in relation to multiple physical function measures. The study hypothesis here was that higher dietary ALA, EPA, DHA and total omega-3 PUFA intake associate with better clinical markers of muscle function and muscle mass and lower fart mass among older women aged 65–72 years.
The main result of the present cross-sectional study was that dietary intake of ALA and total omega-3 PUFA were positively associated with physical function assessments, including faster walking speed 10 m, better performance at one leg stance, ability to squat to the ground and SPPB. Higher ALA quartile was also associated with greater grip strength and lower fat mass. Findings showed no statistically significant association for dietary EPA and DHA with physical function assessments.
The study population is characterized by a high intake of omega-3 PUFA and ALA. The analysis of 3-day food record in this study showed that OSTPRE-FPS older women consumed EPA + DHA 0.41 ± 0.47 (g/day), ALA 1.4 ± 0.8 g/day (corresponding to 0.83% of the mean energy intake), and total omega-3 PUFA 8.8 ± 3.4 g/day, which all are within the range of recommendation by Nordic Nutrition recommendation 2012: minimum 1 E% from n-3 fatty acids and intake of EPA + DHA up to 200–250 mg/day.
There are multiple potential mechanisms which can explain the observed association in this study. Low grade inflammation has been considered as important trigger for inflammation occurring with aging, which is a chronic state of slightly increased plasma levels of pro-inflammatory mediators, such as tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and C-reactive protein (CRP). Without pronouncing the causal links between inflammatory mediator and physical function, the current literature suggests that nutritional factors and particularly omega-3 PUFA are among the biological mechanism to reduce low grade inflammation which can play role to delay or prevent the onset of physical function decline. The finding of this study on positive association for omega-3 PUFA, and ALA with physical function outcomes can be explained by these underlying mechanisms, however, further studies on effect of omega-3 PUFA on muscle function and muscle protein synthesis are required. Besides, the positive finding may be explained by the indirect relationship of omega-3 PUFA as they can improve blood lipid profile and heart function which in turn are associated with healthy ageing. This study suggests that the role of fatty acids should be considered more in the whole dietary approach rather than single nutrients which may explain the inconsistent results of previous studies.