Daily flaxseed consumption improves glycemic control in obese men and women with pre-diabetes: a randomized study.
Daily flaxseed consumption improves glycemic control in obese men and women with pre-diabetes: a randomized study.
Year: 2013
Authors: Hutchins, A.M. Brown, B.D. Cunnane, S.C. Domitrovich, S.G. Adams, E.R. Bobowiec, C.E.
Publication Name: Nutr. Res.
Publication Details: doi.org/10.1016/j.nutres.2013.02.012
Abstract:
The study hypothesis was that fasting glucose, insulin, fructosamine, C reactive protein, and Interleukin 6 decrease and adiponectin increases with daily flaxseed consumption in
overweight or obese individuals with prediabetes. In this randomized, cross-over study overweight or obese men and postmenopausal women (n of 25) with prediabetes consumed 0,
13, or 26 g ground flaxseed for 12 weeks. Glucose, insulin, homeostatic model assessment (HOMA IR), and normalized percent of alpha linolenic fatty acid (ALA) were significantly different by treatment (multiple analysis of variance, P .036, P .013, P .008, P .024 respectively).
Paired t tests showed glucose decreased on the 13 g intervention compared to the 0 g period [13g = −2.10 ± 1.66 mg/L (mean ± SEM), 0 g = 9.22 ± 4.44 mg/L, P .036]. Insulin decreased on the 13 g intervention but not the 26 g (P .021) and 0 g (P .013) periods (13 g = −2.12 ± 1.00mU/L, 26 g = 0.67 ± 0.84 mU/L, 0g = 1.20 ± 1.16 mU/L). HOMA IR decreased on the 13 g period but not on the 26 g (P .012) and 0 g (P .008) periods (13g = −0.71 ± 0.31, 26g = 0.27 ± 0.24, 0g = 0.51 ± 0.35). The ALA fatty acid decrease for the 0 g period was different than the 13 g (P .024) and 26g (P .000) periods (13 g = 0.20 ± 0.04, 26g = 0.35 ± 0.07, 0g = −0.01 ± 0.07).
Fructosamine, high sensitivity C reactive protein, adiponectin, and high sensitivity interleukin 6 had no significant differences. Flaxseed intake decreased glucose and insulin and improved insulin sensitivity as part of a habitual diet in overweight or obese individuals with pre diabetes. (Authors abstract)
Inclusion of omega 3 fatty acids in the diet is associated with improvements in insulin sensitivity and glycemic control. Flaxseed contains soluble fiber, ALA, and linoleic acid. It is also the richest source of the lignan secoisolariciresinol diglucoside, which, after ingestion, is further metabolized to enterodiol and enterolactone. A growing body of evidence suggests that secoisolariciresinol diglucoside metabolites and flaxseed consumption may protect against the metabolic syndrome and risk of progressing from pre-diabetes to type 2 diabetes by reducing lipid and glucose concentrations, delaying postprandial glucose absorption and decreasing oxidative stress and inflammation. The current study was conducted to determine the effect of flaxseed consumption on glycemic control, cytokines, and adipokines in overweight and obese individuals with prediabetes. A randomized crossover study was conducted to determine the impact of consuming 13 or 26 g (2 or 4 tablespoons) of ground flaxseed, compared to a control period for 12 weeks on fasting glucose, insulin, fructosamine, CRP, IL6, and adiponectin in 11 overweight or obese men and 14 overweight or obese postmenopausal women with pre diabetes. The current study found that a low dose of daily flaxseed supplementation decreased insulin resistance in overweight and obese, glucose-intolerant people. Fasting insulin values significantly decreased with daily consumption of 13 g of ground flaxseed compared to 0 g (control) or 26 g ground flaxseed. There were, however, no significant differences for change in plasma insulin between 26 g ground flaxseed and the control intervention. Similarly, 13 g ground flaxseed significantly decreased plasma glucose and the HOMA-IR index compared to control (0 g flaxseed) but there were no differences for change in glucose or HOMA-IR index between 13 g and 26 g ground flaxseed or between 26 g flaxseed and control. Fasting fructosamine values did not change with daily consumption of 13 or 26 g ground flaxseed. No significant differences in IL6 or CRP between the 3 treatment periods was found.
The mechanism(s) by which flaxseed exerts its effect on glycemic control has yet to be fully identified and a plausible explanation for the observed changes with the low-dose intervention but not the high-dose intervention has yet to be documented. Flaxseed contains two components that have been reported to influence the incidence of pre-diabetes as well as type 2 diabetes: soluble fiber and lignans.
In conclusion, the authors indicated that regular low dose (13 g) flaxseed consumption improves biomarkers for prediabetes, including insulin, glucose, HOMA-IR and fructosamine values. This study was designed as a short-term trial and, based on the results obtained, provides enough preliminary evidence to support a longer term multicenter trial exploring this relationship. A longer term trial should include measurement of HbA1c in addition to fructosamine as markers of long term glycemic control. (Editors comments)
