Alpha-linolenic acid supplementation and resistance training in older adults

January 1, 2009 Human Health and Nutrition Data 0 Comments

Alpha-linolenic acid supplementation and resistance training in older adults

Year: 2009
Authors: Cornish, S.M. Chillibeck, P.D.
Publication Name: Appl. Physiol. Nutr. Metab.
Publication Details: Volume 34; Pages 49 to 59.


Increased inflammation with aging has been linked to sarcopenia. The purpose of this study was to evaluate the effects of supplementing older adults with alpha-linolenic acid (ALA) during a resistance training program, based on the hypothesis that ALA decreases the plasma concentration of the inflammatory cytokine tumor necrosis factor (TNF)-a and interleukin (IL)-6, which in turn would improve muscle size and strength. Fifty-one older adults (65.4 +/-  0.8 years) were randomized to receive ALA in flax oil (~14 g/day) or placebo for 12 weeks while completing a resistance training program (3 days a week). Subjects were evaluated at baseline and after 12 weeks for muscle thickness of knee and elbow flexors and extensors (B-mode ultrasound), muscle strength (1 repetition maximum), body composition (dual energy X-ray absorptiometry), and concentrations of TNF-a and IL-6. Males supplementing with ALA decreased IL-6 concentration over the 12 weeks (36% decrease; p = 0.003), with no other changes in inflammatory cytokines. Chest and leg press strength, lean tissue mass, muscle thickness, hip bone mineral content and density, and total bone mineral content significantly increased, and percent fat and total body mass decreased with training (p < 0.05), with the only benefit of ALA being a significantly greater increase in knee flexor muscle thickness in males (p < 0.05). Total-body bone mineral density improved in the placebo group, with no change in the ALA group (p = 0.05). ALA supplementation lowers the IL-6 concentration in older men but not women, but had minimal effect on muscle mass and strength during resistance training. (Author's abstract)
Loss of muscle mass and bone mineral is a major health concern associated with aging. Chronic low-grade inflammation is one factor contributing to decreased muscle mass and strength with age. The inflammatory cytokine interleukin (IL)-6 is associated with a decrease in muscle mass, strength, and fiber number in older adults. TNF-a, is considered a catabolic signaling agent, and increasing levels due to the aging process result in decreased muscle mass and strength. TNF-a stimulates the progressive deterioration of myocytes via apoptosis High concentrations of TNF-a and IL-6 are associated with increased bone resorption, which may be one reason for increased bone loss with age. Strength training is an effective means of improving muscle mass and strength, as well as preserving bone mass, in older adults.  Supplementation with n-3 fatty acids has been used to decrease the amount of inflammation associated with various disease processes. Increasing consumption of ALA will increase EPA concentration in men and women, but the conversion is lower in men than in women. ALA is effective at inhibiting gene expression of inducible nitric oxide synthase, COX-2, and TNF-a by blocking nuclear factor kappa B and mitogen-activated protein kinases. The purpose of this research was to evaluate the effectiveness of ALA supplementation on markers of inflammation and muscle mass and strength in older adults completing a progressive resistance training program. The authors hypothesize that ALA would decrease the chronic low-grade inflammation associated with aging, which, in turn, would result in greater increases in muscle mass and strength during a resistance training program. Secondarily, they also hypothesized that the reduction in chronic low-grade inflammation with ALA would improve bone mineral content and bone mineral density more than placebo during a resistance training program. The results of this study indicate that older men supplementing with ALA for 12 weeks during resistance training decreased the concentration of IL-6, but no effect was seen in women.  The changes in TNF-a concentration mirrored the pattern of IL-6, but did not reach statistical significance for differences between groups. These results seem to suggest an anti-inflammatory effect of ALA in older men, but not in older women. A factor that may have influenced responsiveness to the interventions between males and females is the difference in baseline body composition (i.e., lean tissue mass) between males and females. Including women in our study may have decreased the statistical power to detect changes in inflammatory cytokines with ALA supplementation. A larger study with only men may be needed to detect significant effects of ALA on measures such as strength, muscle mass, and bone mineral density. The results indicate that progressive resistance training is effective for increasing muscle thickness, muscle strength, and lean tissue mass in older adults, but the addition of ALA to the strength training program resulted in minimal improvement in these variables.  Because this study did not measure the acute effects of contracting skeletal muscle on IL-6 concentration, it is not known whether ALA supplementation has an inhibitory effect on the release of IL-6 from contracting skeletal muscle. The study is limited, in that a group that consumed ALA and did not exercise or a group that did not consume ALA or perform exercise training, were not included.  In conclusion, the results of this study suggest that ALA supplementation for 12 weeks reduces the plasma concentration of IL-6 in older men, but not older women, and that progressive resistance training remains an effective method for reducing the risk of sarcopenia and osteoporosis in older adults. (Editor's comments)

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