Elsevier

Nutrition Research

Volume 34, Issue 9, September 2014, Pages 814-820
Nutrition Research

Nut consumption has favorable effects on lipid profiles of Korean women with metabolic syndrome

https://doi.org/10.1016/j.nutres.2014.08.011Get rights and content

Abstract

Nut consumption has been studied for its cardioprotective effects. However, the findings of clinical intervention studies are inconsistent; and no intervention studies have been conducted in the Korean population. We hypothesized that nut supplementation may have favorable influence on metabolic markers. Therefore, this study aimed to investigate the effects of nut consumption on metabolic parameters and biomarkers related to inflammation, oxidative stress, and endothelial function in Korean adults with metabolic syndrome. To this end, we designed a randomized, parallel, controlled dietary intervention study (ClinicalTrials.gov NCT02023749). Subjects with metabolic syndrome and a body mass index of at least 23 kg/m2 were randomized to the Control group and the Nut group, which received supplementation with 30 g/d of mixed nuts (walnuts, peanuts, and pine nuts) for 6 weeks. Sixty volunteers were included in the final analysis. Metabolic markers were evaluated at baseline and at the end of the study. Total cholesterol and non–high-density lipoprotein cholesterol levels significantly improved in the Nut group compared to those in the Control group (P = .023 and P = .016, respectively) in women. Biomarkers related to inflammation, oxidative stress, and endothelial function did not significantly change from baseline in either group. Thus, supplementing a usual diet with mixed nuts for 6 weeks had favorable effects on several lipid parameters in Korean women with metabolic syndrome. These findings present a possible mechanism for the cardioprotective effects of nut consumption.

Introduction

Metabolic syndrome is a cluster of metabolic abnormalities including abdominal obesity, dyslipidemia, elevated blood pressure, and hyperglycemia; and it is associated with significant risk for cardiovascular disease [1]. Metabolic syndrome affects almost one-quarter of the adult population, and its prevalence is increasing globally [2].

Previous studies have indicated that dietary habits are important for the prevention and control of metabolic syndrome. For example, a Mediterranean diet, which includes nuts, is associated with a low risk of metabolic syndrome [3], [4]. Nuts are complex foods that are rich in macronutrients including unsaturated and polyunsaturated fatty acids, micronutrients, fiber, and other bioactive phytonutrients [5]. Previous studies showed that the cardioprotective effects of nut consumption are attributed to the improved insulin sensitivity, endothelial function, or anti-inflammatory action of nuts [6], [7].

Meanwhile, the association between nut consumption and metabolic syndrome has mainly been evaluated in epidemiologic studies. Although some clinical trials have investigated the beneficial effects of nut consumption on metabolic syndrome, their results were inconsistent [8], [9], [10]. Moreover, no such clinical trial has been conducted in a Korean population, in which the prevalence of metabolic syndrome is rapidly increasing [11].

We hypothesized that nut consumption may have a beneficial effects on metabolic variables. Therefore, this study aimed to investigate the effects of nut consumption on metabolic parameters and biomarkers related to inflammation, oxidative stress, and endothelial function in Korean adults with metabolic syndrome.

Section snippets

Study subjects

Volunteers aged 35 to 65 years were screened for this study. We recruited study subjects who underwent a health examination at a university hospital and from advertising in Ansan, South Korea. According to the power calculations, a sample size of 31 subjects was needed to detect a mean difference of 12 mg/dL, with standard deviations (SD) of 15, in low-density lipoprotein cholesterol (LDL-C) to provide 80% power at a significance level of P < .05. Subjects were enrolled in this study if their

Results

Of the 61 randomized participants, 1 withdrew from the study for personal reasons. Sixty subjects (30 in the Nut group and 30 in the Control group) completed the study and were included in the final analyses (Fig. 1). Compliance with the dietary intervention was calculated as 98% based on the daily self-record.

At baseline, age, lifestyle characteristics, anthropometric and biochemical parameters, total daily energy, and nutrient intake were similar between the 2 intervention groups. Table 1

Discussion

In this 6-week, parallel, randomized, controlled dietary intervention trial in Korean adults with metabolic syndrome, a diet supplemented with 30 g of mixed nuts improved several lipid parameters including TC and non–HDL-C in women; but it had no effect on biomarkers related to inflammation, oxidative stress, and endothelial function.

The fatty acids, other specific lipids, and bioactive macronutrients present in nuts have the potential to improve metabolic and cardiovascular outcomes. The

Acknowledgment

This research was supported by a grant (12161MFDS118) from the Ministry of Food and Drug Safety in 2012. The authors declare no conflicts of interest.

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    All authors disclose no financial or other substantive conflict of interest that might be construed to influence the results or interpretation of the results of this manuscript.

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