A randomized controlled trial of the effects of flaxseed lignan complex on metabolic syndrome composite score and bone mineral in older adults
A randomized controlled trial of the effects of flaxseed lignan complex on metabolic syndrome composite score and bone mineral in older adults
Year: 2009
Authors: Cornish, S.M. Chillibeck, P.D. Paus-Jennsen, L. Biem, H.J. Khozani, T. Senanayake, V. Vatanparast, H. et. al.
Publication Name: Appl. Physiol. Nutr. Metab.
Publication Details: Volume 34; Pages 89 to 98.
Abstract:
A randomized double-blind placebo controlled study design was used to assess the effects of flaxseed lignin complex supplementation during exercise training on a metabolic syndrome composite score and osteoporosis risk in older adults. A total of 100 subjects (>50 years) were randomized to receive flaxseed lignan (543 mg /day in a 4050 mg complex) or placebo while completing a 6 month walking program (30 to 60 min/day, 5 to 6 days/week). Fasting serum glucose, triacylglycerol (TAG), high-density lipoprotein (HDL) cholesterol, low-density lipoprotein cholesterol, total cholesterol, interleukin-6, and tumor necrosis factor-a were measured every 2 months, while body composition, bone mineral density, and resting blood pressure were assessed at baseline and at 6 months. A composite Z score of 6 risk factors for metabolic syndrome (fasting glucose, HDL cholesterol, TAG, abdominal adiposity, blood pressure, and inflammatory cytokines) was calculated at baseline and at 6 months. Men taking placebo increased metabolic syndrome composite Z score (p < 0.05), but there were no changes in the other groups. A significant group – sex – time interaction was noted for TAG (p = 0.017) and diastolic blood pressure (p = 0.046), with men taking flaxseed lignan decreasing diastolic blood pressure relative to men taking placebo, and men taking placebo increasing TAG relative to men taking flax lignan. There were no differences between groups for change in bone measures, body composition, lipoproteins, or cytokines. Males taking the flaxseed lignan complex reduced metabolic syndrome score relative to men taking placebo, but a similar trend was not seen in females. Flaxseed lignan had no effect on bone mineral density or content, body composition, lipoproteins, glucose, or inflammation. (Author's abstract)
The flaxseed lignan secoisolariciresinol diglucoside (SDG) is a phytoestrogen that exerts weak estrogenic or antiestrogenic effects in mammalian tissue, depending on the estrogen receptor. There is a lack of consistency surrounding the potential of the lignan component of flaxseed to effect blood lipid profiles, antioxidant capacity, or endothelial function in humans and there has been no assessment of supplementation with flaxseed lignan complex on lipid profiles in healthy older males, or on inflammatory cytokines, BMD, or BMC in healthy older adults. The primary purpose of this study was to assess the efficacy of supplementation with flaxseed lignan complex on a composite score of metabolic syndrome in healthy older men and women completing an exercise program designed to improve the blood lipid profile. The authors hypothesized that older adults completing an exercise program and supplementing their diet with flaxseed lignan complex would lower their metabolic syndrome composite score, compared with those taking a placebo supplement while completing the same exercise program. A secondary purpose was to determine the effects of flaxseed lignan complex on bone measures. The results indicate that a composite score of metabolic syndrome increased in men in the placebo group, but not in men in the flax lignan group over 6 months. There were no differences between women in the placebo group and those in the flax lignan group. A composite score for metabolic syndrome increased over time in older males in the placebo group, but not in men in the flax lignan group. There were no differences between females in the placebo group and those in the flax lignan group. There was no effect of flaxseed lignan supplementation on TAG in postmenopausal women. In men lignan did not have an effect on TAG; rather, the interaction between men in the placebo group and those in the flax lignan group over time was due to an increase in TAG concentration in the placebo group. No differences between the flax lignan and placebo groups were noted over time in lipoprotein concentrations. The subjects had a mix of normal and abnormal lipid profiles; however, sub-analyses on those subjects with lipid levels outside the normal reference range indicated no effect of SDG on lipid profiles. Men supplementing their diets with the flaxseed lignan complex lowered diastolic blood pressure. Men and women in subgroups of subjects with metabolic syndrome at baseline also decreased diastolic blood pressure over time with the flaxseed lignan complex. No changes in bone quantity were found between flax lignan or placebo supplementation in older adults, but the study is limited as it did not assess bone quality. For combined groups, increases in lumbar spine BMC and BMD, and decreases in body mass and BMI over time were observed. These results confirm that the exercise program was effective for lowering overall body mass and improving lumbar spine bone density. In summary, this study indicates that 6 months of supplementation with flaxseed lignan complex (543 mg/day of SDG) resulted in a decrease in composite score of metabolic syndrome, relative to placebo, in males. All males in our study and males and females with metabolic syndrome in the flax lignan group reduced their diastolic blood pressure, relative to placebo. All males in the group and males in the subsample of subjects with metabolic syndrome in the placebo group increased their TAG levels, compared with those in the flax lignan group. Flaxseed lignan complex had no effect on BMC or BMD. Further research is necessary in a larger cohort over a longer period of time to confirm these results. (Editor's comments)
The flaxseed lignan secoisolariciresinol diglucoside (SDG) is a phytoestrogen that exerts weak estrogenic or antiestrogenic effects in mammalian tissue, depending on the estrogen receptor. There is a lack of consistency surrounding the potential of the lignan component of flaxseed to effect blood lipid profiles, antioxidant capacity, or endothelial function in humans and there has been no assessment of supplementation with flaxseed lignan complex on lipid profiles in healthy older males, or on inflammatory cytokines, BMD, or BMC in healthy older adults. The primary purpose of this study was to assess the efficacy of supplementation with flaxseed lignan complex on a composite score of metabolic syndrome in healthy older men and women completing an exercise program designed to improve the blood lipid profile. The authors hypothesized that older adults completing an exercise program and supplementing their diet with flaxseed lignan complex would lower their metabolic syndrome composite score, compared with those taking a placebo supplement while completing the same exercise program. A secondary purpose was to determine the effects of flaxseed lignan complex on bone measures. The results indicate that a composite score of metabolic syndrome increased in men in the placebo group, but not in men in the flax lignan group over 6 months. There were no differences between women in the placebo group and those in the flax lignan group. A composite score for metabolic syndrome increased over time in older males in the placebo group, but not in men in the flax lignan group. There were no differences between females in the placebo group and those in the flax lignan group. There was no effect of flaxseed lignan supplementation on TAG in postmenopausal women. In men lignan did not have an effect on TAG; rather, the interaction between men in the placebo group and those in the flax lignan group over time was due to an increase in TAG concentration in the placebo group. No differences between the flax lignan and placebo groups were noted over time in lipoprotein concentrations. The subjects had a mix of normal and abnormal lipid profiles; however, sub-analyses on those subjects with lipid levels outside the normal reference range indicated no effect of SDG on lipid profiles. Men supplementing their diets with the flaxseed lignan complex lowered diastolic blood pressure. Men and women in subgroups of subjects with metabolic syndrome at baseline also decreased diastolic blood pressure over time with the flaxseed lignan complex. No changes in bone quantity were found between flax lignan or placebo supplementation in older adults, but the study is limited as it did not assess bone quality. For combined groups, increases in lumbar spine BMC and BMD, and decreases in body mass and BMI over time were observed. These results confirm that the exercise program was effective for lowering overall body mass and improving lumbar spine bone density. In summary, this study indicates that 6 months of supplementation with flaxseed lignan complex (543 mg/day of SDG) resulted in a decrease in composite score of metabolic syndrome, relative to placebo, in males. All males in our study and males and females with metabolic syndrome in the flax lignan group reduced their diastolic blood pressure, relative to placebo. All males in the group and males in the subsample of subjects with metabolic syndrome in the placebo group increased their TAG levels, compared with those in the flax lignan group. Flaxseed lignan complex had no effect on BMC or BMD. Further research is necessary in a larger cohort over a longer period of time to confirm these results. (Editor's comments)
