Flaxseed in pediatric hyperlipidemia: a placebo-controlled, blinded, randomized clinical trial of dietary flaxseed supplementation for children and adolescents with hypercholesterolemia.

IMPORTANCE Nonpharmacological management of hypercholesterolemia in children is challenging with few available options. OBJECTIVES To determine the safety and efficacy of dietary flaxseed supplementation in the management of hypercholesterolemia in children. DESIGN Four-week placebo-controlled, blinded, randomized clinical trial. SETTING Specialized dyslipidemia clinic at a tertiary pediatric care center. PARTICIPANTS Thirty-two participants aged 8 to 18 years with low-density lipoprotein cholesterol from 135 mg/dL (3.5 mmol/L) to less than 193 mg/dL (5.0 mmol/L). INTERVENTION The intervention group ate 2 muffins and 1 slice of bread daily containing ground flaxseed (30 g flaxseed total). The control group ate muffins and bread substituted with whole-wheat flour. MAIN OUTCOME AND MEASURE Attributable change in fasting lipid profile. RESULTS Dietary flaxseed supplementation resulted in an attributable decrease of -7.35 mg/dL (-0.19 mmol/L) in high-density lipoprotein cholesterol (95% CI, -3.09 to -11.60 mg/dL[-0.08 to -0.30 mmol/L]; relative: -15%, 95% CI, -24% to -6%; P = .001), an increase of 29.23 mg/dL (+0.33 mmol/L) in triglycerides (95% CI, 4.43 to 53.14 mg/dL [+0.05 to +0.60 mmol/L]; relative: +26%, 95% CI, +4% to +48%; P = .02), and an increase of +4.88 g/d in dietary polyunsaturated fat intake (95% CI, +0.22 to +9.53; relative: +76%, 95% CI, +3% to +148%; P = .04). Flaxseed had no attributable effects on total cholesterol (-8.51 mg/dL [-0.22 mmol/L]; 95% CI, -21.66 to 4.25 mg/dL [-0.56 to +0.11 mmol/L]; relative: -4%, 95% CI, -10% to +2%; P = .20), low-density lipoprotein cholesterol (-6.96 mg/dL [-0.18 mmol/L]; 95% CI, -16.63 to 2.71 mg/dL [-0.43 to +0.07 mmol/L]; relative: -5%, 95% CI, -12% to +2%; P = .15), body mass index z score (+0.002; 95% CI, -0.147 to +0.150; relative: +0%, 95% CI, -12% to +12%; P = .30), or total caloric intake (+117 kcal; 95% CI, -243 to +479; relative: +8%, 95% CI, -17% to +33%; P = .52). An attributable change in total and low-density lipoprotein cholesterol failed to exclude a potential benefit of flaxseed supplementation based on a prespecified minimum clinically important reduction of 10%. No concerns were noted regarding safety. CONCLUSIONS AND RELEVANCE The use of dietary flaxseed supplementation, while safe, was associated with adverse changes in the lipid profile of children with hypercholesterolemia, although a potential benefit of low-density lipoprotein cholesterol lowering could not be excluded. The use of flaxseed supplementation in children with hypercholesterolemia might not be a viable option for lipid management in this population. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01007344.