Wharton B A
Department of Human Nutrition, Yorkhill Hospitals, University of Glasgow, Scotland, United Kingdom.
J Nutr. 1989 Dec;119(12 Suppl):1768-72; discussion 1816-7. doi: 10.1093/jn/119.12_Suppl.1768.
It is clearly necessary to set upper limits for a nutrient in a formula where the nutrient can have a direct toxic effect (e.g., vitamin A) or can lead to a reduced margin of safety (e.g., high dietary renal solute load during gastroenteritis). In addition, there are plausible arguments for setting upper limits for any nutrient added during manufacture. Various expert groups have used different approaches in setting upper limits, particularly for fat and minerals. Evidence of clinical toxicity and various biochemical measurements have been commonly used to determine appropriate upper levels. Less use has been made of the empirical evidence provided by nutrient concentrations in commonly used foods, e.g., breast milk and cow's milk. Four "rules" for setting maxima are suggested: a) Use evidence of clinical toxicity or reduced margin of safety if available; b) Avoid nutrient concentrations that lead to biochemical values in body fluids or tissues very different from those seen in breast-fed babies; c) An upper limit should be set for even apparently harmless nutrients that are added during manufacture; and d) When a nutrient is added, its final concentration should not normally exceed that in breast or cow's milk, whichever is the greater. Using these "rules," suggested maxima for 33 nutrients are listed.
显然，对于配方奶中可能具有直接毒性作用（如维生素A）或可能导致安全边际降低（如胃肠炎期间高膳食肾溶质负荷）的营养素，设定上限是必要的。此外，对于生产过程中添加的任何营养素设定上限也有合理的理由。各个专家小组在设定上限时采用了不同的方法，特别是对于脂肪和矿物质。临床毒性证据和各种生化测量通常用于确定适当的上限。较少利用常用食物（如母乳和牛奶）中营养素浓度提供的经验证据。提出了设定最大值的四条“规则”：a）如有可用的临床毒性或降低的安全边际证据，则使用该证据；b）避免营养素浓度导致体液或组织中的生化值与母乳喂养婴儿中所见的生化值有很大差异；c）对于生产过程中添加的即使看似无害的营养素也应设定上限；d）添加营养素时，其最终浓度通常不应超过母乳或牛奶中的浓度，以较高者为准。使用这些“规则”，列出了33种营养素的建议最大值。
