Abstract
Being rich in polyunsaturated fatty acids, flaxseed (Linum usitatissimum L.) is thought to be able to decrease lipid levels and dampen inflammation. In this pilot study, we aimed to determine whether flaxseed supplementation could improve the profiles of lipids and inflammatory mediators in patients with severe hyperlipidemia resistant to conventional lipid-lowering pharmacotherapy and requiring lipoprotein apheresis. To this end, six patients received, blindly-in addition to their normal lipoprotein apheresis regimen-a 10-week dietary supplementation with flaxseed (28 g/d) administered in biscuits. This was followed by a 10-week washed out-period and a 10-week supplementation phase with whole wheat placebo. Blood samples were collected at the end of each phase, before the lipoprotein apheresis session. The primary endpoint was the lipid profile and the secondary endpoints were the concentrations of inflammatory mediators and tolerability. Flaxseed supplementation was well-tolerated and resulted in a consistent and significant decrease in total cholesterol and low-density lipoprotein (LDL) levels. The median (and range) percentage decrease was 11.5% (0-18.8) and 7.3% (4.4-26.6), for cholesterol (p = 0.015) and LDL-C (p = 0.003), respectively. On the other hand, there was no significant effect of flaxseed on lipoprotein(a) (Lp(a)), C-reactive protein (CRP), and interleukin 6 (IL-6) concentrations. These observations indicate that flaxseed can produce a cholesterol- and LDL-lowering effect in patients treated with lipoprotein apheresis. Thus, flaxseed supplementation may help to control cholesterol in this patient population. The flaxseed supplementation protocol applied may be of use for further adequately-powered studies to validate and extend our findings.
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Key Points
Nonpharmacological management of severe hypercholesterolemia is challenging and includes lifestyle changes. These may be more appealing to patients while reducing the risk of cardiovascular disease. Flaxseed is recommended as a functional food for patients with hypercholesterolemia. There are few reports indicating that flaxseed can be of benefit for such a patient population. A recent meta-analysis of sixty-two randomized controlled trials with a total of 3772 participants suggested that flaxseed supplementation can reduce total serum cholesterol, triglyceride, and LDL in unhealthy subjects with high baseline lipids level. This pilot study confirms and extends these observations. It shows that flaxseed supplementation for 10 weeks is feasible and well-tolerated and is capable of reducing total cholesterol and LDL by 5–10% even in patients for whom lipoprotein apheresis seemed to be the only treatment option available. As these patients also received pharmacotherapy, the effect of flaxseed is even more impressive. In contrast to LDL and cholesterol, a significant reduction in Lp(a) levels was not seen following flaxseed treatment. A reduction in HDL, triglycerides, and other lipids after flaxseed supplementation was found suggesting that flaxseed is targeting the cholesterol pathway more specifically. The absence of significant changes in these patients could be related to the fact that levels of inflammatory parameters (as exemplified by CRP) were already very low at baseline. Being a pilot hypothesis-driven exploration, this study clearly demonstrates that the applied protocol of flaxseed supplementation gains patients’ acceptance and is well-tolerated. Moreover, it demonstrates a significant cholesterol-lowering effect in such complex patients as those treated with lipoprotein apheresis. This may be of clinical relevance and indicate that flaxseed should be included in the diet regularly.