Flaxseed lignan lowers blood cholesterol and decreases liver disease risk factors in moderately hypercholesterolemic men
Flaxseed lignan lowers blood cholesterol and decreases liver disease risk factors in moderately hypercholesterolemic men
Year: 2010
Authors: Fukumitsu, S. Aida, K. Shimizu, H. Toyoda, K.
Publication Name: Nutrition Research
Publication Details: Volume 30; Pages 441 – 446.
Abstract:
The effects of flaxseed lignan (secoisolariciresinol diglucoside [SDG]) intake on hypercholesterolemia and liver disease risk factors in moderately hypercholesterolemic men were investigated. In a previous study, we reported that SDG attenuates high-fat, diet-induced hypercholesterolemia in mice. Here, we report a double-blinded, randomized, and placebo-controlled study in moderately hypercholesterolemic men in which we investigated the hypothesis that oral administration of SDG (20 or 100 mg) would decrease the level of blood cholesterol and liver disease risk factors induced by hypercholesterolemia in humans. Thirty men with total cholesterol levels of 4.65 to 6.21 mmol/L (180-240 mg/dL) were randomly assigned to 3 groups; 2 groups received flaxseed lignan capsules (SDG, 20 or 100 mg/d) and the other received placebo capsules for 12 weeks. We found that, compared to the subjects who received placebo, those who received 100 mg of SDG exhibited a significant reduction in the ratio of low-density lipoprotein/high density lipoprotein cholesterol at baseline (P b .05) and at week 12 (P b .05). In addition, in SDG treated subjects, we also observed a significant percentage decrease in the levels of glutamic pyruvic transaminase and γ�glutamyl transpeptidase relative to the levels at baseline (P b .01) and a significant percentage decrease in the level of γ�glutamyl transpeptidase relative to the placebo treated group (P b .05). These results suggest that daily administration of 100 mg SDG can be effective at reducing blood level of cholesterol and hepatic diseases risk in moderately hypercholesterolemic men. (Authors abstract)
Metabolic syndrome which is characterized by visceral obesity, dyslipidemia, hyperglycemia, and hypertension has been gradually increasing over the last few years. Ingestion of the lignan secoisolariciresinol diglucoside (SDG) is converted by bacteria in the colon to the biologically active lignans enterodiol (END) and enterolactone (ENL). These SDG metabolites possess antioxidant activity and have been shown to protect humans against hormone-dependent cancers, such as breast and prostate cancers. Previous work by this group demonstrated that administration of SDG to mice attenuates high-fat, diet-induced liver fat accumulation, hypercholesterolemia. It was hypothesized that a low dose of SDG (20 mg or 100 mg), compared to the higher levels of SDG used in previous human research, would decrease the cholesterol levels in moderately hypercholesterolemic men. Further, it was thought that oral administration of SDG would decrease the level of liver disease risk factors induced by hypercholesterolemia in humans, but not rodents. In this study, the objective was to investigate the effects of 20 mg and 100 mg SDG intake on hypercholesterolemia and liver disease risk factors in moderately hypercholesterolemic men for 12 weeks. The intake of 100 mg of SDG for 12 weeks resulted in a significant decrease in the ratio of LDL/HDL cholesterol, which is an important predictor of the risk of CVD in moderately hypercholesterolemic men. The changes in total and LDL cholesterol levels at baseline and week 12 of the subjects tended to be lower in the 100-mg SDG group than in the placebo group. Further, this treatment regimen also significantly decreased the waist circumference of the subjects relative to that at baseline. In addition, subjects who were administered 100 mg of SDG exhibited significant percentage decreases in the levels of biomarkers of liver injury, GPT and γ-GTP (relative to baseline) and of γ-GTP (relative to placebo) at week 12. The mechanism(s) underlying the cholesterol-lowering effects of flaxseed lignan have not been elucidated. A decrease in the mRNA expression levels of SREBP-1c in the liver may underlie the blood cholesterol-lowering effects. This is the first study to report that oral administration of SDG decreased the level of liver disease risk factors induced by hypercholesterolemia in humans. Further investigation with a larger cohort is needed to confirm the effective SDG dose that can be practically ingested on a daily basis on lipid metabolism. The findings do suggest that a low dose of flaxseed or flaxseed lignan could beneficially affect hypercholesterolemia and liver disease risk factors in humans. (Editors comments)
Metabolic syndrome which is characterized by visceral obesity, dyslipidemia, hyperglycemia, and hypertension has been gradually increasing over the last few years. Ingestion of the lignan secoisolariciresinol diglucoside (SDG) is converted by bacteria in the colon to the biologically active lignans enterodiol (END) and enterolactone (ENL). These SDG metabolites possess antioxidant activity and have been shown to protect humans against hormone-dependent cancers, such as breast and prostate cancers. Previous work by this group demonstrated that administration of SDG to mice attenuates high-fat, diet-induced liver fat accumulation, hypercholesterolemia. It was hypothesized that a low dose of SDG (20 mg or 100 mg), compared to the higher levels of SDG used in previous human research, would decrease the cholesterol levels in moderately hypercholesterolemic men. Further, it was thought that oral administration of SDG would decrease the level of liver disease risk factors induced by hypercholesterolemia in humans, but not rodents. In this study, the objective was to investigate the effects of 20 mg and 100 mg SDG intake on hypercholesterolemia and liver disease risk factors in moderately hypercholesterolemic men for 12 weeks. The intake of 100 mg of SDG for 12 weeks resulted in a significant decrease in the ratio of LDL/HDL cholesterol, which is an important predictor of the risk of CVD in moderately hypercholesterolemic men. The changes in total and LDL cholesterol levels at baseline and week 12 of the subjects tended to be lower in the 100-mg SDG group than in the placebo group. Further, this treatment regimen also significantly decreased the waist circumference of the subjects relative to that at baseline. In addition, subjects who were administered 100 mg of SDG exhibited significant percentage decreases in the levels of biomarkers of liver injury, GPT and γ-GTP (relative to baseline) and of γ-GTP (relative to placebo) at week 12. The mechanism(s) underlying the cholesterol-lowering effects of flaxseed lignan have not been elucidated. A decrease in the mRNA expression levels of SREBP-1c in the liver may underlie the blood cholesterol-lowering effects. This is the first study to report that oral administration of SDG decreased the level of liver disease risk factors induced by hypercholesterolemia in humans. Further investigation with a larger cohort is needed to confirm the effective SDG dose that can be practically ingested on a daily basis on lipid metabolism. The findings do suggest that a low dose of flaxseed or flaxseed lignan could beneficially affect hypercholesterolemia and liver disease risk factors in humans. (Editors comments)
