Flaxseed supplementation improved insulin resistance in obese glucose intolerant people: a randomized crossover design

Abstract

Background: Obesity leads to an increase in inflammation and insulin resistance. This study determined antioxidant activity of flaxseed and its role in inflammation and insulin resistance in obese glucose intolerant people.

Methods: Using a randomized crossover design, nine obese glucose intolerant people consumed 40 g ground flaxseed or 40 g wheat bran daily for 12 weeks with a 4-week washout period. Plasma inflammation biomarkers (CRP, TNF-α, and IL-6), glucose, insulin, and thiobaribituric acid reactive substance (TBARS) were measured before and after of each supplementation.

Results: Flaxseed supplementation decreased TBARS (p = 0.0215) and HOMA-IR (p = 0.0382). Flaxseed or wheat bran supplementation did not change plasma inflammatory biomarkers. A positive relationship was found between TBARS and HOMA-IR (r = 0.62, p = 0.0003).

Conclusions: The results of the study weakly support that decreased insulin resistance might have been secondary to antioxidant activity of flaxseed. However, the mechanism(s) of decreased insulin resistance by flaxseed should be further determined using flaxseed lignan.

Figure 1

Fasting plasma insulin concentrations before and after each supplementation. Data are presented as mean ± standard error, n = 7-9; Statistical significance level was set at 0.05. *Significantly decreased after 12 weeks of wheat bran supplementation compared to the baseline, p = 0.026. No significant change in plasma insulin concentration after 12 weeks of flaxseed supplementation. No significant differences in plasma insulin concentration between flaxseed and wheat bran supplementation groups

Figure 2

HOMA-IR index before and after each supplementation. Data are presented as mean ± standard error, n = 7-9; Statistical significance level was set at 0.05. *Significantly decreased after 12 weeks of flaxseed supplementation compared to the baseline, p = 0.0382. No significant change in HOMA-IR after 12 weeks of wheat bran supplementation. No significant differences in HOMA-IR between flaxseed and wheat bran supplementation groups

Figure 3

Plasma TBARS concentrations before and after each supplementation¹. ¹TBARS is an indicator for lipid peroxidation, and it is measured in MDA equivalents. Data are presented as mean ± standard error, n = 7-9; Statistical significance level was set at 0.05. *Significantly decreased after 12 weeks of flaxseed supplementation compared to the baseline, p = 0.0215. No significant change in plasma TBARS concentration after 12 weeks of wheat bran supplementation. No significant differences in plasma TBARS concentration between flaxseed and wheat bran supplementation groups