食品组分对铁的化学状态和其生物利用率的影响及其机制研究
发布时间：2018-08-13 11:35
【摘要】：1.研究背景 世界卫生组织(wHO)认为,在发展中国家,超过2亿人存在铁缺乏。而2002年中国居民营养与健康状况调查显示,全国平均贫血率为20.1%。由此可见,铁缺乏及其所导致的贫血,是世界范围内普遍存在的公共卫生问题。 生物利用率是正常身体功能所利用的矿物质在食品总矿物质中所占的比例,所以说,生物利用率是研究矿物质吸收的关键。影响铁生物利用率的因素包括铁的化学形态、人体的生理因素、铁转运吸收机制以及膳食因子。食物环境对铁生物利用率的影响主要是由于不同的食物环境和人体环境中铁的化学形态不同,诸如离子化程度、化合价以及与食物中其它成分是否能形成络合物及络合物的溶解性与稳定性。食物中存在的膳食因素有的明显具有还原性和络合性,会影响铁的存在形式,进而可能会影响影响铁的吸收率 本部分研究首先探讨维生素C、半胱氨酸等具有还原性的膳食因素对铁价念的影响以及相应条件下Caco-2细胞的铁吸收情况,同时研究赖氨酸、组氨酸、半胱氨酸、植酸盐、酒石酸等具有络合性的膳食因素对铁的络合状态的影响。 2.研究方法 首先,本研究将改良并确立一种可行的铁价态分析方法。其次,在模拟生理条件下,利用之前确立的方法和参考方法,分析食物组分对铁的价态和络合状态的影响情况。最后,利用Caco-2细胞模型分析不同膳食因素对Fe(Ⅱ)或Fe(Ⅲ)吸收率的影响,并且通过剂量反应关系和联系膳食因素的化学结构,探讨膳食因素影响铁吸收的原因和机制。 2.1基于邻二氮菲的铁价态分析方法的改良 (1)吸收波长的确定。 (2)设立避光对照组,分别显色测定吸光度。 (3)比较氯化铵、EDTA、NTA三种金属掩蔽剂是否对Fe(Ⅱ)的测定有干扰。 (4)比较NTA掩蔽剂和显色剂直接分光光度法测量Fe(Ⅱ)的准确度。 (5)比较还原法和双波长分光光度法测定总铁的准确度。 2.2体外模拟生理条件下探讨膳食因子对铁存在形态的影响 (1)体外模拟人体生理条件。 (2)测定膳食因子对铁的螯合能力。 (3)测定膳食因子对铁的还原能力。 2.3食品组分对铁的生物利用率的影响及作用机制的研究 (1)建立Caco-2细胞模型并进行吸收实验。 (2)采用酸法消化结合ICP-AES测定铁含量。 3.研究结果 3.1基于邻二氮菲的铁价态分析方法的改良 采用掩蔽剂可以很好的解决光化学反应问题,比较适合的Fe(Ⅲ)掩蔽剂为NTA。显色剂直接分光法适用范围较窄,当总铁中的Fe(Ⅲ)含量≥52%时,方法相对误差较大,变得不稳定,而总铁中的Fe(Ⅲ)含量≤90%时,NTA掩蔽法即可使用。应用两种控制图及95%置信区间图证明,还原法更准确可靠。 3.2体外模拟生理条件下探讨膳食因子对铁存在形态的影响 (1)在体外模拟生理条件下,随着抗坏血酸／半胱氨酸与Fe(Ⅲ)的摩尔比增加,其还原率不断增加。 (2)在相同摩尔比下,不同有机酸对Fe(Ⅱ)的络合能力不同；在同一种有机酸不同摩尔比下,随着草酸/植酸与Fe(Ⅱ)摩尔比的增加,其对Fe(Ⅱ)的络合率升高。 (3)在相同摩尔比下,不同氨基酸对Fe(Ⅱ)的络合能力不同；在同一种氨基酸不同摩尔比下,随着半胱氨酸/甲硫氨酸/赖氨酸/亮氨酸/色氨酸/缬氨酸/异亮氨酸/组氨酸与Fe(Ⅱ)摩尔比的增加,其对Fe(Ⅱ)的络合率升高。 3.3食品组分对铁的生物利用率的影响及作用机制的研究 (1)Fe(Ⅱ)对照组吸收率明显高于Fe(Ⅲ)对照组吸收率,这证明了Fe(Ⅱ)通过DMT1及NRAMP2进入肠上皮细胞机制的存在。同时,除1：1摩尔比组外,还原率和吸收率高度正相关,这说明抗坏血酸的还原性在促进铁吸收过程中作用很大。 (2)酒石酸对Fe(Ⅱ)的吸收存在促进作用。酒石酸对Fe(Ⅱ)吸收的影响明显和络合率呈正相关。植酸对铁吸收的最大抑制作用发生在两者摩尔浓度比为10：1,超过该值后其抑制作用无显著增加。草酸对Fe(Ⅱ)吸收的影响复杂：(1)在Fe(Ⅱ)/草酸的摩尔比≥1：5时,草酸表现为抑制作用；(2)在Fe(Ⅱ)/草酸的摩尔比等于1：10时,表现为促进作用；(3)在Fe(Ⅱ)／草酸的摩尔比≤1：50时,草酸作用不明显。 (3)半胱氨酸对Fe(Ⅲ)和Fe(Ⅱ)的吸收具有明显的促进作用,Fe(Ⅲ)的还原率和吸收率存在很强的正相关,其对Fe(Ⅲ)还原作用是影响其吸收的关键因素。 (4)本次研究将氨基酸分为三组,并且结合这些种类氨基酸供／吸电子效应及相应化学结构分析了其影响机制。
[Abstract]:1. research background
The World Health Organization (WHO) believes that iron deficiency exists in more than 200 million people in developing countries. The 2002 National Survey on Nutrition and Health Status of Chinese Residents shows that the national average anemia rate is 20.1%. Thus, iron deficiency and anemia caused by iron deficiency are widespread public health problems worldwide.
Bioavailability is the proportion of minerals used by normal body function in total minerals of food, so bioavailability is the key to the study of mineral absorption. Factors affecting iron bioavailability include chemical forms of iron, physiological factors of the human body, iron transport and absorption mechanisms, and dietary factors. The effects of food and human environments on the availability of iron are mainly due to the different chemical forms of iron, such as ionization degree, valence, solubility and stability of complexes and complexes with other components in food. The existing form of ring iron may affect the absorption rate of iron.
In this part, the effects of reducing dietary factors such as vitamin C and cysteine on iron valence and iron uptake by Caco-2 cells under the corresponding conditions were investigated. The effects of complex dietary factors such as lysine, histidine, cysteine, phytate and tartaric acid on iron complexation were also studied.
2. research methods
Firstly, this study will improve and establish a feasible method of iron valence analysis. Secondly, under simulated physiological conditions, the effects of food components on the valence and complexation of iron are analyzed by using the previously established methods and reference methods. Finally, Caco-2 cell model is used to analyze the absorption of Fe (II) or Fe (III) by different dietary factors. The effect of dietary factors on iron absorption was investigated by dose-response relationship and chemical structure of dietary factors.
2.1 an improved method for analyzing iron valence state based on adjacent two phenanthrene
(1) determination of absorption wavelength.
(2) set up a light avoiding control group, and measure the absorbance separately.
(3) compare whether the three metal masking agents of ammonium chloride, EDTA and NTA interfere with the determination of Fe (II).
(4) to compare the accuracy of Fe (II) measurement with NTA masking agent and chromogenic reagent directly spectrophotometric method.
(5) to compare the accuracy of the reduction method and the dual wavelength spectrophotometry for the determination of total iron.
2.2. Effects of dietary factors on iron speciation in vitro under simulated physiological conditions
(1) simulate human physiological conditions in vitro.
(2) determine the chelating ability of dietary factors to iron.
(3) to determine the reduction ability of dietary factors to iron.
2.3 effect of food components on iron bioavailability and its mechanism
(1) establish Caco-2 cell model and conduct absorption experiments.
(2) determination of iron content by acid digestion combined with ICP-AES.
3. research findings
3.1 an improved method for analyzing iron valence state based on adjacent two phenanthrene
Using masking agent can solve the problem of photochemical reaction very well. The suitable Fe(III) masking agent is NTA. The application range of direct Spectrophotometry with color reagent is narrow. When the content of Fe(III) in total iron is more than 52%, the relative error of the method is large and becomes unstable. When the content of Fe(III) in total iron is less than 90%, NTA masking method can be used. The graph and the 95% confidence interval diagram show that the reduction method is more accurate and reliable.
3.2. Effects of dietary factors on iron speciation in vitro under simulated physiological conditions
(1) Under simulated physiological conditions in vitro, the reduction rate of ascorbic acid/cysteine increased with the increase of molar ratio of ascorbic acid/cysteine to Fe(III).
(2) At the same molar ratio, the complexing ability of different organic acids to Fe(II) is different, and the complexing rate of oxalic acid/phytic acid to Fe(II) increases with the increase of the molar ratio of oxalic acid/phytic acid to Fe(II).
(3) At the same molar ratio, the complexation ability of different amino acids to Fe(II) is different; at the same molar ratio of amino acids, the complexation rate of Fe(II) increases with the increase of the molar ratio of cysteine/methionine/lysine/leucine/tryptophan/valine/isoleucine/histidine to Fe(II).
3.3 effect of food components on iron bioavailability and its mechanism
(1) The absorption rate of Fe (II) in the control group was significantly higher than that in the Fe (III) control group, which proved the existence of the mechanism of Fe (II) entering intestinal epithelial cells through DMT1 and NRAMP2. In addition, there was a highly positive correlation between the reduction rate and the absorption rate except for the 1:1 molar ratio group, indicating that the reducibility of ascorbic acid played an important role in promoting iron absorption.
(2) Tartaric acid can promote the absorption of Fe (II). The effect of tartaric acid on the absorption of Fe (II) is obviously positively correlated with the complexation rate. The maximum inhibitory effect of phytic acid on the absorption of Fe (II) occurs at the molar concentration ratio of 10:1. The inhibitory effect of phytic acid on the absorption of Fe (II) does not increase significantly when the molar concentration ratio exceeds this value. When the molar ratio of acid is more than 1:5, oxalic acid shows inhibition; (2) when the molar ratio of Fe (II) / oxalic acid is equal to 1:10, oxalic acid shows promotion; (3) when the molar ratio of Fe (II) / oxalic acid is less than 1:50, oxalic acid has no obvious effect.
(3) Cysteine can obviously promote the absorption of Fe (III) and Fe (II). There is a strong positive correlation between the reduction rate and the absorption rate of Fe (III). The reduction effect of cysteine on Fe (III) is the key factor affecting its absorption.
(4) In this study, amino acids were divided into three groups, and the mechanism was analyzed by combining the electron-donating and electron-absorbing effects of these amino acids and their corresponding chemical structures.
【学位授予单位】：中国疾病预防控制中心
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R151.2
本文编号：2180865
[Abstract]:1. research background
The World Health Organization (WHO) believes that iron deficiency exists in more than 200 million people in developing countries. The 2002 National Survey on Nutrition and Health Status of Chinese Residents shows that the national average anemia rate is 20.1%. Thus, iron deficiency and anemia caused by iron deficiency are widespread public health problems worldwide.
Bioavailability is the proportion of minerals used by normal body function in total minerals of food, so bioavailability is the key to the study of mineral absorption. Factors affecting iron bioavailability include chemical forms of iron, physiological factors of the human body, iron transport and absorption mechanisms, and dietary factors. The effects of food and human environments on the availability of iron are mainly due to the different chemical forms of iron, such as ionization degree, valence, solubility and stability of complexes and complexes with other components in food. The existing form of ring iron may affect the absorption rate of iron.
In this part, the effects of reducing dietary factors such as vitamin C and cysteine on iron valence and iron uptake by Caco-2 cells under the corresponding conditions were investigated. The effects of complex dietary factors such as lysine, histidine, cysteine, phytate and tartaric acid on iron complexation were also studied.
2. research methods
Firstly, this study will improve and establish a feasible method of iron valence analysis. Secondly, under simulated physiological conditions, the effects of food components on the valence and complexation of iron are analyzed by using the previously established methods and reference methods. Finally, Caco-2 cell model is used to analyze the absorption of Fe (II) or Fe (III) by different dietary factors. The effect of dietary factors on iron absorption was investigated by dose-response relationship and chemical structure of dietary factors.
2.1 an improved method for analyzing iron valence state based on adjacent two phenanthrene
(1) determination of absorption wavelength.
(2) set up a light avoiding control group, and measure the absorbance separately.
(3) compare whether the three metal masking agents of ammonium chloride, EDTA and NTA interfere with the determination of Fe (II).
(4) to compare the accuracy of Fe (II) measurement with NTA masking agent and chromogenic reagent directly spectrophotometric method.
(5) to compare the accuracy of the reduction method and the dual wavelength spectrophotometry for the determination of total iron.
2.2. Effects of dietary factors on iron speciation in vitro under simulated physiological conditions
(1) simulate human physiological conditions in vitro.
(2) determine the chelating ability of dietary factors to iron.
(3) to determine the reduction ability of dietary factors to iron.
2.3 effect of food components on iron bioavailability and its mechanism
(1) establish Caco-2 cell model and conduct absorption experiments.
(2) determination of iron content by acid digestion combined with ICP-AES.
3. research findings
3.1 an improved method for analyzing iron valence state based on adjacent two phenanthrene
Using masking agent can solve the problem of photochemical reaction very well. The suitable Fe(III) masking agent is NTA. The application range of direct Spectrophotometry with color reagent is narrow. When the content of Fe(III) in total iron is more than 52%, the relative error of the method is large and becomes unstable. When the content of Fe(III) in total iron is less than 90%, NTA masking method can be used. The graph and the 95% confidence interval diagram show that the reduction method is more accurate and reliable.
3.2. Effects of dietary factors on iron speciation in vitro under simulated physiological conditions
(1) Under simulated physiological conditions in vitro, the reduction rate of ascorbic acid/cysteine increased with the increase of molar ratio of ascorbic acid/cysteine to Fe(III).
(2) At the same molar ratio, the complexing ability of different organic acids to Fe(II) is different, and the complexing rate of oxalic acid/phytic acid to Fe(II) increases with the increase of the molar ratio of oxalic acid/phytic acid to Fe(II).
(3) At the same molar ratio, the complexation ability of different amino acids to Fe(II) is different; at the same molar ratio of amino acids, the complexation rate of Fe(II) increases with the increase of the molar ratio of cysteine/methionine/lysine/leucine/tryptophan/valine/isoleucine/histidine to Fe(II).
3.3 effect of food components on iron bioavailability and its mechanism
(1) The absorption rate of Fe (II) in the control group was significantly higher than that in the Fe (III) control group, which proved the existence of the mechanism of Fe (II) entering intestinal epithelial cells through DMT1 and NRAMP2. In addition, there was a highly positive correlation between the reduction rate and the absorption rate except for the 1:1 molar ratio group, indicating that the reducibility of ascorbic acid played an important role in promoting iron absorption.
(2) Tartaric acid can promote the absorption of Fe (II). The effect of tartaric acid on the absorption of Fe (II) is obviously positively correlated with the complexation rate. The maximum inhibitory effect of phytic acid on the absorption of Fe (II) occurs at the molar concentration ratio of 10:1. The inhibitory effect of phytic acid on the absorption of Fe (II) does not increase significantly when the molar concentration ratio exceeds this value. When the molar ratio of acid is more than 1:5, oxalic acid shows inhibition; (2) when the molar ratio of Fe (II) / oxalic acid is equal to 1:10, oxalic acid shows promotion; (3) when the molar ratio of Fe (II) / oxalic acid is less than 1:50, oxalic acid has no obvious effect.
(3) Cysteine can obviously promote the absorption of Fe (III) and Fe (II). There is a strong positive correlation between the reduction rate and the absorption rate of Fe (III). The reduction effect of cysteine on Fe (III) is the key factor affecting its absorption.
(4) In this study, amino acids were divided into three groups, and the mechanism was analyzed by combining the electron-donating and electron-absorbing effects of these amino acids and their corresponding chemical structures.
【学位授予单位】：中国疾病预防控制中心
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：R151.2
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