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Food & Funct.:每天吃7个核桃可预防疾病降血脂

来源:新浪健康 2012-02-02 15:03

近日,《食品和功能》杂志刊登了一项研究成果美国科学家通过对9种坚果的对比研究发现,核桃摘得“坚果之王”桂冠,因为核桃富含多种抗氧化剂,最有益健康。每天吃7个核桃有助于防止多种疾病,降低血胆固醇。常吃坚果,好处多多。

美国宾夕法尼亚州斯克兰顿大学科学家发现,核桃中富含的多酚(polyphenol)可保护人体免受自由基侵害。在所有坚果中,无论生吃还是熟吃,核桃的多酚含量都位居第一,紧随其后的是巴西坚果、开心果、碧根果、花生、杏仁和澳洲坚果,而腰果和榛子的多酚含量相对较低。不过从市场份额看,花生名列第一。据统计,花生占据欧洲坚果市场的45%。研究还发现,花生酱中的抗氧化剂含量低于烘焙花生。

新研究负责人乔·文森教授表示,核桃还可以抑制人体内“坏胆固醇”(LDL)的增加。原因是,核桃等坚果富含纤维、有益健康的不饱和脂肪和大量的抗氧化剂,而饱和脂肪含量极低。常吃坚果零食,可帮助人体获得对健康至关重要的多种营养和活性抗氧化剂。

新研究发现,生核桃中的抗氧化剂的作用是维生素E的15倍,可保护身体免受自然化学物质的伤害。烘焙腰果中的抗氧化剂水平是维生素E的两倍。碧根果的含锌量可满足日需求量的六分之一,而锌有助于改善白血球功能,提高免疫力,抗击感冒和流感等细菌和病菌。两把去壳开心果的钾含量比一根香蕉中的钾还多。钾是人体代谢过程中的重要营养素,对排除体内多余盐分至关重要。巴西坚果富含硒,硒对人体细胞具有保护作用,而且可降低膀胱癌和前列腺癌等多种癌症的危险。(生物谷 Bioon.com)

Nuts, especially walnuts, have both antioxidant quantity and efficacy and exhibit significant potential health benefits

Joe A. Vinson and Yuxing Cai

Free and total (after basic hydrolysis) polyphenols in nine types of raw and roasted nuts and two types of peanut butter (54 commercial samples) were analyzed after methanol extraction by a single step Folin-Ciocalteu reagent using catechin as standard. Walnuts had the highest free and total polyphenols in both the combined raw and roasted samples. Total polyphenols in the nuts were significantly higher than free polyphenols. Roasting had little effect on either free or total polyphenols in nuts. Raw and roasted walnuts had the highest total polyphenols. The efficacy of raw and roasted nut antioxidants was assessed by measuring the ability of the free polyphenol nut extracts to inhibit the oxidation of lower density lipoproteins (LDL + VLDL). A nut polyphenol, catechin, was measured after binding of three nut extracts to lower density lipoproteins. Walnut polyphenols had the best efficacy among the nuts and also the highest lipoprotein-bound antioxidant activity. Based on USDA availability data, the per capita total polyphenols was 162 mg from nuts per day in 2008. This corresponds to 19% of the total polyphenols from fruits and vegetables, nuts, grains, oils and spices in the US diet. Nuts provided 158 mg of polyphenols per day to the European Union diet. Nuts are high in polyphenol antioxidants which by binding to lipoproteins would inhibit oxidative processes that lead to atherosclerosis in vivo. In human supplementation studies nuts have been shown to improve the lipid profile, increase endothelial function and reduce inflammation, all without causing weight gain. These qualities make nuts a nutritious healthy snack and food additive.

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