Mnisi Robert Londi, Ndibewu Peter P, Mafu Lihle D, Bwembya Gabriel C
Department of Chemistry, Tshwane University of Technology, Private bag X680, Pretoria 0001, South Africa.
Department of Chemistry, Tshwane University of Technology, Private bag X680, Pretoria 0001, South Africa.
Ecotoxicol Environ Saf. 2017 Oct;144:396-401. doi: 10.1016/j.ecoenv.2017.06.033. Epub 2017 Jun 22.
The green leafy vegetables (Mormodica involucrate, Bidens pilosa and Amaranthus spinosus) are economic; seasonal; locally grown and easily available; easy to propagate and store; highly nutritious food substances that form an important component of diets. This study applies a physiology based extraction technique (PBET) to mimic digestion of these vegetables to determine the fraction of essential (Fe and Zn) and non-essential elements (Cd, Cr and Pb) that are made available for absorption after ingestion. Prior to the application of the PBET, the vegetables were cooked adopting indigenous Swazi cooking methods. Cooking mobilized most of the metals out of the vegetable mass, and the final substrate concentrations are: raw > cooked > supernatant for all the metals, and the order of average metal leaching was: Pb (82.2%) >Cr (70.6%) >Zn (67.5%) >Fe (60.2%) >Cd (53.6%). This meant that the bioavailable concentrations are significantly lower than in the original vegetable mass, if only the solid mass is consumed. Bioaccessibility was higher in the gastric tract than in the intestinal phases of the PBET for all the metals in all the vegetables. Risk assessment protocols employed on the non-essential elements (Cr, Cd and Pb) showed that the associated risks of ingesting metal contaminated vegetables are higher for children, than they are for adults, based on the target hazard quotient (THQ) index. However, the overall health risk associated with ingestion of these metals is low, for both children and adults, based on the HR index. Conclusively, this study expounds on the nutritional and risk benefits associated with ingesting naturally grown vegetables.
绿叶蔬菜（刺角瓜、三叶鬼针草和刺苋）经济实惠、季节性强、本地种植且易于获取、易于繁殖和储存，是构成饮食重要组成部分的高营养食物。本研究应用基于生理学的提取技术（PBET）来模拟这些蔬菜的消化过程，以确定摄入后可被吸收的必需元素（铁和锌）和非必需元素（镉、铬和铅）的比例。在应用PBET之前，采用斯威士兰本土烹饪方法对蔬菜进行烹饪。烹饪使大部分金属从蔬菜中释放出来，所有金属的最终底物浓度顺序为：生蔬菜＞熟蔬菜＞上清液，平均金属浸出顺序为：铅（82.2%）＞铬（70.6%）＞锌（67.5%）＞铁（60.2%）＞镉（53.6%）。这意味着，如果只食用固体部分，生物可利用浓度显著低于原始蔬菜中的浓度。对于所有蔬菜中的所有金属，在PBET的胃肠道阶段生物可及性高于肠道阶段。对非必需元素（铬、镉和铅）采用的风险评估方案表明，基于目标危害商（THQ）指数，儿童摄入受金属污染蔬菜的相关风险高于成人。然而，基于健康风险（HR）指数，儿童和成人摄入这些金属的总体健康风险都较低。总之，本研究阐述了摄入天然种植蔬菜的营养和风险益处。
