Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals

Abstract

Background/Objectives: Walnuts have been shown to reduce serum lipids in short-term well-controlled feeding trials. Little information exists on the effect and sustainability of walnut consumption for longer duration in a free-living situation. Subjects/Methods: A randomized crossover design in which 87 subjects with normal to moderate high plasma total cholesterol were initially assigned to a walnut-supplemented diet or habitual (control) diet for a 6-month period, then switched to the alternate dietary intervention for a second 6-month period. Each subject attended seven clinics 2 months apart. At each clinic, body weight was measured, and in five clinics (months 0, 4, 6, 10 and 12), a blood sample was collected. Results: Our study showed that supplementing a habitual diet with walnuts (12% of total daily energy intake equivalent) improves the plasma lipid profile. This beneficial effect was more significant in subjects with high plasma total cholesterol at baseline. Significant changes in serum concentrations of total cholesterol (P ¼ 0.02) and triglycerides (P ¼ 0.03) were seen and nearly significant changes in low-density lipoprotein cholesterol (LDL-C) (P ¼ 0.06) were found. No significant change was detected in either high-density lipoprotein (HDL) cholesterol LDL to HDL ratio. Conclusions: Including walnuts as part of a habitual diet favorably altered the plasma lipid profile. The lipid-lowering effects of walnuts were more evident among subjects with higher lipid baseline values, precisely those people with greater need of reducing plasma total and LDL-C.

Health Benefits of Nut Consumption

“…Recent well controlled intervention studies with walnuts [71,72,73,74], almonds [75], hazelnuts [76], pistachios [77], macadamias [78], and peanuts [79] showed LDL-cholesterol reductions ranging from 4% to 11% versus comparator diets, confirming the cholesterol-lowering efficacy of various nut types. A Mediterranean diet supplemented with 30 g of mixed nuts (walnuts, almonds and hazelnuts) per day also showed beneficial effects on the lipid profile compared with advice on a low-fat diet in diabetic and non diabetic participants in the PREDIMED study, a randomized trial of dietary intervention for the primary prevention of cardiovascular disease [80].…”

Effects of different forms of hazelnuts on blood lipids and α-tocopherol concentrations in mildly hypercholesterolemic individuals

“…Both epidemiological studies (Fraser et al, 1992;Kushi et al, 1996;Albert et al, 2002;Hu and Willett, 2002) and clinical trials (Kris-Etherton et al, 1999a;Rajaram et al, 2001;Sabate et al, 2003;Gebauer et al, 2008;Griel et al, 2008;Banel and Hu, 2009;Phung et al, 2009;Torabian et al, 2010) have consistently shown that nuts can have an important role in the management of plasma lipids, and reduce CVD morbidity and mortality. The American Heart Association recommends the consumption of nuts as a means of replacing saturated fat with unsaturated fats (Krauss et al, 2000).…”

Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals

“…However, it seems necessary to also present the results with and without control for total energy intake, in addition to the adjustment for body weight. The average total energy consumption for participants on the walnut-supplemented diet and the control diet was 8171 and 7614 kJ, respectively (Torabian et al, 2010). The mean difference between daily total energy intake (557 kJ) during the two diet periods is approximately 50% less than the actual energy intake from walnuts (967 kJ).…”

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In the March 2010 issue of EJCN, Torabian et al (2010) reported the effects of walnut consumption on serum lipids, specifically, total serum cholesterol and low-density lipoprotein (LDL) cholesterol. This randomized crossover trial included 87 subjects who were assigned to a walnutsupplemented group or control group for 6 months and then crossed over to the alternate diet for 6 months.

Although the findings are generally consistent with the results from previous studies (Banel and Hu, 2009), it seems as though this trial could be strengthened with refined analysis and interpretation of the data collected.

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“…In the March 2010 issue of EJCN, Torabian et al (2010) reported the effects of walnut consumption on serum lipids, specifically, total serum cholesterol and low-density lipoprotein (LDL) cholesterol. This randomized crossover trial included 87 subjects who were assigned to a walnutsupplemented group or control group for 6 months and then crossed over to the alternate diet for 6 months.…”