Bioactive oat β-glucan reduces LDL cholesterol in Caucasians and non-Caucasians

Abstract

Background: There is increasing global acceptance that viscous soluble fibers lower serum LDL cholesterol (LDL-C), but most evidence for this comes from studies in Caucasians. To see if oat β-glucan lowers LDL-C in Caucasians and non-Caucasians we conducted a post-hoc analysis of the results of a randomized, controlled, double-blind, multi-center clinical trial whose primary aim was to determine if molecular-weight (MW) influenced the LDL-C-lowering effect of oat β-glucan.

Results: Caucasian and non-Caucasian subjects with LDL-C-C ≥ 3.0 and ≤ 5.0 mmol/L (n = 786 screened, n = 400 ineligible, n = 19 refused, n = 367 randomized, n = 345 completed, n = 1 excluded for missing ethnicity) were randomly assigned to consume cereal containing wheat-fiber (Control, n = 74:13 Caucasian:non-Caucasian) or 3 g high-MW (3H, 2,250,000 g/mol, n = 67:19), 4 g medium-MW (4 M, 850,000 g/mol, n = 50:17), 3 g medium-MW (3M, 530,000 g/mol, n = 54:9) or 4 g low-MW (4 L, 210,000 g/mol, n = 51:12) oat β-glucan daily for 4 weeks. LDL-C after 4 weeks was influenced by baseline LDL-C (p < 0.001) and treatment (p = 0.003), but not ethnicity (p = 0.74). In all subjects, compared to control, 3 H, 4 M and 3 M reduced LDL-C significantly by 4.8 to 6.5%, but 4 L had no effect. Compared to control, the bioactive oat β-glucan treatments (3H, 4M and 3M) reduced LDL-C by a combined mean (95% CI) of 0.18 (0.06, 0.31) mmol/L (4.8%, n = 171, p = 0.004) in Caucasians, a value not significantly different from the 0.37 (0.09, 0.65) mmol/L (10.3%, n = 45, p = 0.008) reduction in non-Caucasians.

Conclusion: We conclude that oat β-glucan reduces LDL-C in both Caucasians and non-Caucasians; there was insufficient power to determine if the magnitude of LDL-C-lowering differed by ethnicity.

Trial registration: ClinicalTrials.gov: NCT00981981.

Figures

Figure 1

Time course of unadjusted percent changes from baseline of LDL-C in Caucasian (C) and non-Caucasian (N) subjects randomly assigned to consume the control cereal (Cont, C:N n = 74:13), or cereals containing 4 g low-MW oat β-glucan (4 L, C:N n = 51:12), 3 g medium-MW oat β-glucan (3 M, C:N n = 54:9), 4 g medium-MW oat β-glucan (4 M, C:N n = 50:17) or 3 g high-MW oat β-glucan (3 H, C:N n = 67:19) daily for 4 weeks. Values represent means ± SEM.

Figure 2

Difference in LDL-C, adjusted for baseline, in Caucasian (C, filled bars) and non-Caucasian (N, open bars) subjects after 4 weeks on cereals containing 4 g low-MW oat β-glucan (4 L, C:N n = 51:12), 3 g medium-MW oat β-glucan (3 M, C:N n = 54:9), 4 g medium-MW oat β-glucan (4 M, C:N n = 50:17) or 3 g high-MW oat β-glucan (3 H, C:N n = 67:19) daily versus mean adjusted-LDL-C after 4 weeks on Control in the same ethnic group. Values are means ± 95% CI.