膳食中硒的摄入与高血压疾病相关性的研究进展

硒是人体必需的微量元素,适量增加硒的摄入可以预防由氧化应激反应造成的高血压疾病,但是过量摄入硒也可能增加罹患高血压的风险。本文综述了国内外膳食中硒的摄入与高血压的关系研究,硒在高血压疾病中的作用机制及国内外硒摄入的现状,以期为为高血压患者选择营养饮食提供参考。     

Increased intakes of selenium‐enriched foods may benefit human health

Selenium is an essential nutrient and deficient intakes compromise health in domestic animals and humans. A recommended dietary allowance (RDA) of 55 µg d^?1 has been set for adult males and females in the United States; most North Americans consume more than this amount, but many residents of Europe, Asia and Africa consume less. While there are very few reports of outright Se deficiency in people consuming mixed Western diets that have Se intakes below the RDA, there is evidence that dietary intakes of selenium greater than the requirement may help reduce the risk of cancer, especially prostate cancer, to men. Selenium metabolism depends on the chemical form of Se in the diet, and some forms are better for some actions (e.g., cancer reduction) than other forms. Foods may contain different amounts and chemical forms of Se; consequently the benefits of Se may depend on the particular foods consumed. There are many reports of the chemistry and health benefits of Se from plant foods; animal foods also contain Se, but there are fewer reported studies. Fully understanding the health benefits of Se that may be gained by consumption of Se‐enriched foods will require multidisciplinary approaches by teams of medical researchers, chemists, nutritionists, and agricultural scientists. Copyright © 2007 Society of Chemical Industry     

Selenium and the prevention of prostate and colorectal cancer

Prostate and colorectal cancers are among the most common cancers and identifying modifiable risk factors are important steps to reduce the burden of these severe diseases. Results from several but mostly small observational studies as well as the secondary analysis of an intervention trial provide support for a chemopreventive effect of selenium on prostate and colorectal cancers. Results suggest effect modification by gender and smoking, but this interpretation is limited by the statistical power of previous studies. Several cancer preventive mechanisms have been described and it is likely that selenium acts through multiple pathways. In particular, the anti-oxidative and anti-inflammatory effects mediated through activity of selenoenzymes are discussed, given the relevance of oxidative stress and inflammation in these cancers. Genetic variation in selenoenzymes may modify the potential chemopreventive effect of selenium and need to be further investigated. Additional large observational studies using biomarkers of selenium intake and intervention trials, such as the Selenium and Vitamin E Cancer Prevention Trial, will be important to further evaluate the potential chemopreventive effect of selenium. Furthermore, characterization of functional effects of polymorphisms in selenoenzymes is needed.     

硒蛋白生理功能研究综述

硒是一种必需微量元素,广泛存在于生物体内。硒蛋白是硒在生物体内实现生理功能的主要载体,是一类含硒代半胱氨酸的蛋白质。硒代半胱氨酸主要位于氧化还原催化位点,具有更高的氧化还原电位。在动、植物体内,硒蛋白主要以氧化还原酶的形式存在,具有调节细胞氧化应激、免疫功能、内质网应激和炎症反应等生物功能特性,对克山病、癌症、阿尔兹海默症等多种疾病具有治疗和预防作用。本文综述硒蛋白的代谢途径、硒蛋白的合成机制及其生理功能特性,以期为硒蛋白研究提供参考。     

微藻富硒生物转化研究进展

硒是人类、动物及部分微生物所必需的微量元素, 在机体内发挥着不可替代的作用, 其安全剂量范围非常窄, 硒摄入量不足或过量都会导致相关疾病的发生。藻类作为水生生态系统的初级生产者, 是水环境中硒的主要吸收者, 能将无机硒转化为有机硒, 是良好的生物富硒载体。本文对硒在水体中的主要形态、微藻对硒的吸收和代谢途径、硒对藻细胞产生的影响及微藻富硒的应用等方面进行论述, 全面解析硒在藻细胞中的转运机理, 为微藻富硒提供理论依据, 提高微藻的附加值, 更好地指导微藻富硒产业发展。     

Authors' perspective: what is the optimum intake of vitamin C in humans?

The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy. While higher intakes of vitamin C may exert additional health benefits, the limited Phase III randomized placebo-controlled trials (RCTs) of vitamin C supplementation have not found consistent benefit with respect to chronic disease prevention. To date, this has precluded upward adjustments of the current RDA. Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients; and the currently available scientific evidence is sufficient to determine the optimum intake of vitamin C in humans. This evidence establishes biological plausibility and mechanisms of action for vitamin C in the primary prevention of coronary heart disease, stroke, and cancer; and is buttressed by consistent data from prospective cohort studies based on blood analysis or dietary intake and well-designed Phase II RCTs. These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers. Furthermore, vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which also may contribute to chronic disease prevention. Based on the combined evidence from human metabolic, pharmacokinetic, and observational studies and Phase II RCTs, we conclude that 200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects.     

食物中硒的研究进展

硒是一种人体必需的微量元素,其功效不仅与含量相关,而且与硒形态及其生物有效性相关。本文总结了硒的摄入量标准,论述了不同类型食物中硒总量和硒形态研究进展,以期为开发和利用富硒食物、合理指导硒营养摄入与补充提供参考。     

Trace minerals intake: Risks and benefits for cardiovascular health

Minerals play a major role in regulating cardiovascular function. Imbalances in electrolyte minerals are frequent and potentially hazardous occurrences that may lead to the development of cardiovascular diseases (CVDs). Transition metals, such as iron, zinc, copper and selenium, play a major role in cell metabolism. However, there is controversy over the effects of dietary and supplemental intake of these metals on cardiovascular risk factors and events. Since their pro-oxidant or antioxidant functions can have different effects on cardiovascular health. While deficiency of these trace elements can cause cardiovascular dysfunction, several studies have also shown a positive association between metal serum levels and cardiovascular risk factors and events. Thus, a J- or U-shaped relationship between the transition minerals and cardiovascular events has been proposed. Given the existing controversies, large, well-designed, long-term, randomized clinical trials are required to better examine the effects of trace mineral intake on cardiovascular events and all-cause mortality in the general population. In this review, we discuss the role of dietary and/or supplemental iron, copper, zinc, and selenium on cardiovascular health. We will also clarify their clinical applications, benefits, and harms in CVDs prevention.     

Oxidation During Digestion of Meat: Interactions with the Diet and Helicobacter pylori Gastritis,and Implications on Human Health

The last decade has seen epidemiological evidence of a positive association between high consumption of red meat and processed meat and the risk of developing a range of chronic diseases, such as colorectal cancer, cardiovascular disease, and type 2 diabetes. Oxidative stress is potentially involved in this association; however, oxidative stress is likely limited if red meat and processed meat are consumed in moderation, and combined with high intake of fruits and vegetables and low intake of refined sugars. In addition, it appears that some subgroups of the population are more prone to developing oxidative stress‐related diseases as a consequence of high red and processed meat consumption. For example, the gastric juice in the inflamed stomach of individuals infected with Helicobacter pylori may be an excellent site for enhanced oxidation following meat consumption. Similarly, patients with inflammatory bowel disease may be at increased risk. Oxidative stress resulting from red or processed meat consumption may mediate the onset and/or progression of a wide range of diseases through various mechanisms, which are discussed in this review.     

Dietary polyphenols and the prevention of diseases

Polyphenols are the most abundant antioxidants in the diet and are widespread constituents of fruits, vegetables, cereals, dry legumes, chocolate, and beverages, such as tea, coffee, or wine. Experimental studies on animals or cultured human cell lines support a role of polyphenols in the prevention of cardiovascular diseases, cancers, neurodegenerative diseases, diabetes, or osteoporosis. However, it is very difficult to predict from these results the effects of polyphenol intake on disease prevention in humans. One of the reasons is that these studies have often been conducted at doses or concentrations far beyond those documented in humans. The few clinical studies on biomarkers of oxidative stress, cardiovascular disease risk factors, and tumor or bone resorption biomarkers have often led to contradictory results. Epidemiological studies have repeatedly shown an inverse association between the risk of myocardial infarction and the consumption of tea and wine or the intake level of some particular flavonoids, but no clear associations have been found between cancer risk and polyphenol consumption. More human studies are needed to provide clear evidence of their health protective effects and to better evaluate the risks possibly resulting from too high a polyphenol consumption.     

硒在“土壤-作物-食品-人体”食物链中的流动

硒是人体内不可缺少的微量营养素,参与体内多种生理和代谢过程,目前全球约5～10亿人受到缺硒相关疾病威胁。在农业-食物系统中,硒主要通过土壤进入食物链,经作物富集,再通过膳食被人体摄入吸收。利用适宜农艺措施增强作物吸收转化土壤硒的能力,可使作物可食部位有效积累有机硒。但作物富硒并不意味着硒可以全部保留至食品中,食品加工环节的影响也极为关键,各种加工条件和参数会影响最终产品的硒含量和形态,从而影响其在人体内的生物利用度。本文综述硒元素在“土壤-作物-食品-人体”食物链中的流动过程,总结各环节影响食品中硒含量、形态和人体中硒生物利用度的关键因素,建议综合考虑各环节因素,以实现从农场到餐桌硒元素的高效转化。     

Environmental selenium research: from microscopic processes to global understanding

Selenium is a natural trace element that is of fundamental importance to human health. The extreme geographical variation in selenium concentrations in soils and food crops has resulted in significant health problems related to deficient or excess levels of selenium in the environment. To deal with these kinds of problems in the future it is essential to get a better understanding of the processes that control the global distribution of selenium. The recent development of analytical techniques and methods enables accurate selenium measurements of environmental concentrations, which will lead to a better understanding of biogeochemical processes. This improved understanding may enable us to predict the distribution of selenium in areas where this is currently unknown. These predictions are essential to prevent future Se health hazards in a world that is increasingly affected by human activities.     

The role of trace elements for the health of elderly individuals.

Elderly individuals have a higher risk to develop trace element deficiencies due to modified dietary habits and requirements, age related physiological changes, drug therapy, and chronic diseases leading to or associated with enhanced consumption or excretion of trace elements. This review gives an overview about the role of zinc, iron, selenium, copper, chromium and fluoride for the health of elderly people in regard of physiological functions, trace element status and intake, and effect of supplementation on clinical parameters and disease outcome.     

The role of trace elements for the health of elderly individuals

Elderly individuals have a higher risk to develop trace element deficiencies due to modified dietary habits and requirements, age related physiological changes, drug therapy, and chronic diseases leading to or associated with enhanced consumption or excretion of trace elements. This review gives an overview about the role of zinc, iron, selenium, copper, chromium and fluoride for the health of elderly people in regard of physiological functions, trace element status and intake, and effect of supplementation on clinical parameters and disease outcome.     

生物活性硒肽的研究进展

硒是人体生长代谢必需的微量元素，而生物活性硒肽是补充有机硒的重要来源。随着对硒及其衍生物相关营养学价值探究的深入，硒肽除却其基础营养价值外的多种潜在健康益处也逐渐被发现。硒肽多从富硒植物中分离，但由于硒资源分布不均和现有生产技术限制，无法满足工业化生产。此外，当前对硒肽的结构尚没有系统性的探究策略，无法为硒肽的构效关系提供更多证据，而蛋白质组学、肽组学等技术的发展对于进一步认识硒肽具有积极作用。本文根据近年来国内外的研究，概述了硒的生物学功能及其代谢途径，并对生物活性硒肽的来源、制备、生物活性、结构特征进行综述，同时对硒肽与不含硒同源肽的生物活性的比较研究进行综述，以期为生物活性硒肽的研究提供理论指导。     

Molecular cross‐talk between members of distinct families of selenium containing proteins

Dietary intake of selenium has been associated with reduced risk of several cancer types, and this is likely due to its role as a specific constituent of selenium containing proteins. One of these, selenium‐binding protein 1 (SBP1), is a protein of unknown function that has been shown to be reduced in tumors of diverse tissue types as compared to the corresponding normal tissue. More importantly, SBP1 has also been reported to be a predictor of clinical outcome. Levels of SBP1 are inversely associated with the levels of another protein representative of a different class of selenoproteins, glutathione peroxidase1 (GPx‐1). GPx‐1 is an anti‐oxidant, selenocysteine containing enzyme implicated in several diseases, including cancer, due to the association of specific alleles with disease risk. The relationship between SBP1 and GPx‐1 represents a unique example of a molecular interaction between selenium containing proteins with a likely significant impact on human health and disease.     

不同形态硒的功效研究进展

硒是人体中必不可少的微量元素之一。现阶段硒以及衍生物的研究已经有一定的基础, 国内外也开始重点研究硒以及硒衍生物的具体作用。硒在有机硒的形态下添加到食品中可以起到预防心血管疾病的作用。有机硒存在人体内也可以起到防止人体器官老化、预防心脏病、预防风湿性关节炎的作用。硒在硒蛋白的形态下也起到维持人体内激素动态平衡, 维持人体生理活动可以正常运转的作用。现如今对硒的诸多深入研究也只是刚刚起步, 本文介绍了硒的2种同形态, 并说明这2种形态下的具体作用机制, 以期让人们更好地理解不同形态硒。硒的更多形态和作用都有很大的研究价值, 今后也应该将硒作为重点研究的对象之一, 更好地将硒利用到各个领域当中。     

Selenium in health and disease: A review

Selenium (Se) was discovered 180 years ago. The toxicological properties of Se in livestock were recognized first; its essential nutritional role for animals was discovered in the 1950s and for humans in 1973. Only one reductive metabolic pathway of Se is well characterized in biological systems, although several naturally occurring inorganic and organic forms of the element exist. The amount of Se available for assimilation by the tissues is dependent on the form and concentration of the element. Se is incorporated into a number of functionally active selenoproteins, including the enzyme glutathione peroxidase, which acts as a cellular protector against free radical oxidative damage and type 1 iodothyronine 5'‐deiodinase which interacts with iodine to prevent abnormal hormone metabolism. Se deficiency has been linked with numerous diseases, including endemic cardiomyopathy in Se‐deficient regions of China; cancer, muscular dystrophy, malaria, and cardiovascular disease have also been implicated, but evidence for the association is often tenuous. Information on Se levels in foods and dietary intake is limited, and an average requirement for Se in the U.K. has no been established. Available data suggest that intake in the U.K. is adequate for all, except for a few risk groups such as patients on total parenteral nutrition or restrictive diets.     

纳米硒制备方法研究进展

硒是一种维护人体和其他生命体健康必需的微量元素,富硒农副产品、食品保护人类健康,越来越广受消费者青睐,但资源严重匮乏,无法满足需求,与无机及有机硒相比,纳米硒毒性低、活性高,是开发新型富硒食品的良好材料,是解决富硒产品资源缺乏的重要途径,纳米硒的合成具有十分重要意义。因此,对纳米硒制备方法进行综述,对纳米硒合成发展进行展望,旨在对富硒产品开发和纳米硒合成创新起到借鉴作用。     

Distribution of supplemental selenium in the serum, hair, colostrum, and fetus of parturient dairy cows

A selenium supplementation study was conducted with Holstein cows to evaluate amounts and methods of administration, namely, oral supplementation (1 vs. 2 mg/head/d, last 60 d of gestation) and intramuscular injection (50 mg at 40 and 20 d prepartum vs. 50 mg at 60, 40, and 20 d prepartum). Blood was collected every 10 d, starting 60 d prepartum and extending 20 d postpartum for cows, and at birth to 20 d for calves. Hair samples of cows were obtained at 60 to 40 and 20 d prepartum, and of the calves at birth. Colostrum samples were obtained for assay. Oral (2 mg/d) and both injection treatments resulted in increased selenium in serum of cows, but selenium in serum of calves at birth was greater only for those whose dams received selenium by injection. Selenium in hair of cows was increased by both injection treatments as well as by the oral treatment of 2 mg/d. Selenium in hair of calves was increased by all methods of administering selenium to the dams. Selenium in colostrum was not affected by any treatment. Thus, pregnant dairy cattle respond to selenium supplementations of a daily oral intake of 2 mg/head/d, the last 60 d of gestation, or by injection of 50 mg each on d 40 and 20 prepartum.