这是用户在 2024-4-15 15:55 为 https://app.immersivetranslate.com/pdf-pro/8e8835f0-6ec5-4f11-908c-2e97be68e556 保存的双语快照页面，由 沉浸式翻译 提供双语支持。了解如何保存？
2024_04_15_bff988731b69f003211dg

Estimation of net endogenous noncarbonic acid production in humans from diet potassium and protein contents
从饮食钾和蛋白质含量 估计人类内源性非碳酸净产量

Lynda A Frassetto, Karen M Todd, R Curtis Morris Jr, and Anthony Sebastian
琳达·弗拉塞托、凯伦·托德、小柯蒂斯·莫里斯和安东尼·塞巴斯蒂安

Abstract 抽象

Normal adult humans eating Western diets have chronic, low-grade metabolic acidosis, the severity of which is determined in part by the net rate of endogenous noncarbonic acid production (NEAP), which varies with diet. To prevent or reverse age-related sequelae of such diet-dependent acidosis (eg, bone and muscle loss), methods are needed for estimating and regulating NEAP. Because NEAP is difficult to measure directly, we sought a simple method to estimate it from diet-composition data. We focused on protein and potassium contents because the production of sulfuric acid from protein metabolism and bicarbonate from dietary potassium salts of organic acids are the major variable components of NEAP. Using steady state renal net acid excretion (RNAE) as an index of NEAP in 141 normal subjects eating 20 different diets, we found by multiple linear regression analysis that RNAE [mEq/d 10460 kJ diet (mEq/d 2500 kcal)] was predictable from protein [g/d 10460 kJ diet kcal); positive regression coefficient, and potassium diet ; negative regression coefficient, ] contents, which were not themselves correlated. Among diets, of the variation in RNAE could be accounted for by the ratio of protein (Pro) to potassium (K) content: RNAE Pro . Thus, by considering both the acidifying effect of protein and the alkalinizing effect of potassium (organic anions), NEAP can be predicted with confidence from the readily available contents of only 2 nutrients in foods. Provisionally, these findings allow estimation and regulation of NEAP through diet modification. Am J Clin Nutr 1998;68:576-83.
吃西餐的正常成年人患有慢性、低度代谢性酸中毒，其严重程度部分取决于内源性非碳酸产生 （NEAP） 的净速率，该速率随饮食而变化。为了预防或逆转这种饮食依赖性酸中毒的年龄相关后遗症（例如骨骼和肌肉流失），需要估计和调节NEAP的方法。由于NEAP很难直接测量，因此我们寻求一种简单的方法来从饮食成分数据中估计它。我们专注于蛋白质和钾含量，因为蛋白质代谢产生的硫酸和有机酸的膳食钾盐产生的碳酸氢盐是NEAP的主要可变成分。使用稳态肾净酸排泄 （RNAE） 作为 141 名正常受试者吃 20 种不同饮食的 NEAP 指标，我们通过多元线性回归分析发现 RNAE [mEq/d 10460 kJ 饮食 （mEq/d 2500 kcal）] 可预测蛋白质 [g/d 10460 kJ 饮食 kcal）;正回归系数和 钾 饮食 ;负回归系数， ]内容，其本身不相关。在饮食中， RNAE的变化可以通过蛋白质（Pro）与钾（K）含量的比率来解释：RNAE Pro 。因此，通过考虑蛋白质的酸化作用和钾（有机阴离子）的碱化作用，可以从食物中仅含有2种营养素的现成含量中可靠地预测NEAP。暂时，这些发现允许通过饮食调整来估计和调节NEAP。美国临床营养杂志 1998;68：576-83。

KEY WORDS Endogenous acid production, renal net acid excretion, potassium, protein, diet, metabolic acidosis
关键词 内源性酸产生， 肾净酸排泄， 钾， 蛋白质， 饮食， 代谢性酸中毒

INTRODUCTION 介绍

Normal adult humans eating typical American diets characteristically have chronic, low-grade metabolic acidosis (1-4). That persisting perturbation of systemic acid-base equilibrium occurs because metabolism of the diet releases noncarbonic acids into the systemic circulation (eg, sulfuric acid from metabolism of protein) in amounts that exceed the amounts of base released concomitantly (eg, bicarbonate from combustion of organic acid salts of potassium in vegetable foods) . The size of the discrepancy between acid and base production determines the net endogenous acid production rate (ie, the net acid load of the diet), which in turn determines the degree of perturbation of systemic acid-base equilibrium . Under normal physiologic circumstances, the net endogenous acid production rate and the degree of the attendant low-grade metabolic acidosis are determined primarily by the composition of the diet .
食用典型美国饮食的正常成年人通常患有慢性低代谢性酸中毒 （1-4）。系统酸碱平衡的持续扰动之所以发生，是因为饮食的新陈代谢将非碳酸释放到体循环中（例如，蛋白质代谢产生的硫酸），其量超过了伴随释放的碱的量（例如，植物性食物中钾的有机酸盐燃烧产生的碳酸氢盐） .酸和碱产之间的差异大小决定了内源性酸的净产酸率（即日粮的净酸负荷），这反过来又决定了全身酸碱平衡的扰动程度 。在正常生理情况下，净内源性酸产生率和随之而来的低度代谢性酸中毒的程度主要由饮食 的组成决定。
With advancing age, the severity of diet-dependent acidosis increases independently of diet . That occurs because kidney function ordinarily declines substantially with age, resulting in a condition similar to that of chronic renal insufficiency (7). Renal insufficiency induces metabolic acidosis by reducing conservation of filtered bicarbonate and excretion of acid. Failure to recognize the respective and independent roles of age-related impaired renal acid-base regulatory capacity and diet net acid load has until recently prevented the recognition that low-grade metabolic acidosis is characteristically present and worsens with age in otherwise healthy adults .
随着年龄的增长，饮食依赖性酸中毒的严重程度与饮食 无关。这是因为肾功能通常会随着年龄的增长而大幅下降，导致类似于慢性肾功能不全的病症（7）。肾功能不全通过减少过滤碳酸氢盐的保存和酸的排泄来诱导代谢性酸中毒。直到最近，由于未能认识到与年龄相关的肾酸碱调节能力受损和饮食净酸负荷的各自和独立作用，人们才认识到低级别代谢性酸中毒在其他方面健康的成年人 中具有特征性存在并随着年龄的增长而恶化。
The pathophysiologic implications of this chronic, low-grade, diet-dependent, age-amplified metabolic acidosis have been examined by determining the effects of neutralizing the net acid load of the diet with a dietary supplement of base, namely potassium bicarbonate. Potassium bicarbonate is a natural base that the body generates from the metabolism of organic acid salts of potassium (eg, potassium citrate) (8), whose density (ie, mmol food item) is greatest in fruit and vegetables. Long-term supplementation of the diet with potassium bicarbonate has numerous anabolic effects. In postmenopausal women for example, calcium and phosphorus balances improve (1), bone resorption markers decrease (1), bone formation markers increase (1), nitrogen balance improves (9), and serum growth hormone concentrations increase (10). These findings suggest that the adverse effects of chronic, low-grade, diet-dependent acidosis are not inconsequential and may contribute to such age-related disturbances as bone mass decline, osteoporosis, and muscle wasting.
这种慢性、低级别、饮食依赖性、年龄放大的代谢性酸中毒的病理生理学意义已经通过确定用碱膳食补充剂（即碳酸氢钾）中和饮食的净酸负荷的效果来检查。碳酸氢钾是人体从钾的有机酸盐（如柠檬酸钾）代谢中产生的天然碱（8），其密度（即mmol 食品）在水果和蔬菜中最大。长期补充碳酸氢钾具有许多合成代谢作用。例如，在绝经后妇女中，钙和磷平衡改善 （1），骨吸收标志物减少 （1），骨形成标志物增加 （1），氮平衡改善 （9），血清生长激素浓度增加 （10）。这些发现表明，慢性、低级别、饮食依赖性酸中毒的不良反应并非无关紧要，并且可能导致骨量下降、骨质疏松症和肌肉萎缩等与年龄相关的障碍。
One way to reduce or eliminate diet-dependent metabolic acidosis is by eating diets that impose little or no net acid load. Present methods for estimating the net acid load from the composition of the diet require a detailed inventory of nutrient composition and estimates of the gastrointestinal absorption rates of the nutrients; these methods have been validated for only a few diets (11, 12). In vivo methods for quantifying net endogenous acid production are complex and labor intensive (5) and are suitable only for specialized clinical research centers. Accordingly, simple dietary guidelines for quantifying and regulating endogenous acid production rates do not exist. In this paper we present a new method for estimating the net acid load of the diet from readily available information on diet composition, specifically total protein and potassium contents. We focused on these 2 components because the rate of sulfuric acid production from protein metabolism and the rate of bicarbonate generation from metabolism of intestinally absorbed potassium salts of organic acids are major and highly variable components of the net endogenous acid production rate . This paper describes the empirically derived relations between these 2 components in different diets and how they can be used to predict net endogenous acid production.
减少或消除饮食依赖性代谢性酸中毒的一种方法是吃摄入很少或没有净酸负荷的饮食。目前从饮食成分中估计净酸负荷的方法需要详细的营养成分清单和营养素的胃肠道吸收率估计;这些方法仅在少数饮食中得到验证（11,12）。用于定量内源性酸净产量的体内方法复杂且劳动密集型 （5），仅适用于专门的临床研究中心。因此，量化和调节内源性酸产生率的简单膳食指南并不存在。在本文中，我们提出了一种新方法，用于根据饮食成分的现成信息，特别是总蛋白质和钾含量来估计饮食的净酸负荷。我们之所以关注这两个成分，是因为蛋白质代谢产生的硫酸速率和肠道吸收的有机酸钾盐代谢产生的碳酸氢盐的速率是净内源性酸产生速率 的主要且高度可变的成分。本文描述了这两种成分在不同饮食中的经验推导关系，以及如何利用它们来预测内源性酸的净产生。

SUBJECTS AND METHODS 主题和方法

For this study of normal subjects, we used the steady state rate of renal net acid excretion (RNAE) as an index of the net rate of endogenous noncarbonic acid production (NEAP) . We measured RNAE in 42 subjects, each of whom ate 1 of 6 different whole-food diets while residing in the University of California, San Francisco (UCSF) General Clinical Research Center. In addition, we obtained values of RNAE from the literature for 99 subjects eating of 14 whole-food diets for which pertinent data on nutrient composition were reported (5, 11-15). In some cases the same subjects were restudied while ingesting a second or third diet (5, 11, 13-15). Data were accumulated for 20 different whole-food diets ingested by 141 different subjects, reflecting a total of 199 subject-diet combinations. All subjects ingested a diet for , a period previously shown to be sufficient for establishing a steady state of acid-base equilibrium (2). Selected articles provided at minimum data on diet protein, potassium, and energy contents. We excluded articles in which diets were supplemented with mineral salts because such salts typically supply acid or base equivalents.
对于正常受试者的这项研究，我们使用肾脏净酸排泄的稳态速率 （RNAE） 作为内源性非碳酸产生净速率 （NEAP） 的指标。我们测量了 42 名受试者的 RNAE，他们每个人在加州大学旧金山分校 （UCSF） 综合临床研究中心居住期间吃了 6 种不同的全食物饮食中的 1 种。此外，我们从文献中获得了 99 名食用 14 种全食物饮食的受试者的 RNAE 值，这些饮食报告了有关营养成分的相关数据 （5， 11-15）。在某些情况下，在摄入第二或第三饮食时重新研究了相同的受试者（5,11,13-15）。积累了 141 名不同受试者摄入的 20 种不同全食物饮食的数据，总共反映了 199 种受试者饮食组合。所有受试者都摄入了一段饮食， 这段时间先前被证明足以建立酸碱平衡的稳定状态 （2）。选定的文章提供了关于饮食蛋白质、钾和能量含量的最低限度数据。我们排除了饮食中补充矿物盐的文章，因为这些盐通常提供酸或碱当量。

Subjects 科目

The subjects were healthy men and women. Subjects participating in the UCSF General Clinical Research Center studies signed informed consent documents as specified by the university's committee on human research. The subjects ranged in age from 17 to [data on age are lacking for 8 subjects in one article (5)].
受试者是健康的男性和女性。参与加州大学旧金山分校综合临床研究中心研究的受试者签署了该大学人类研究委员会规定的知情同意书。受试者的年龄从17岁到 [一篇文章（5）中缺少8名受试者的年龄数据]。

Diets 饮食

Values for protein, potassium, and energy contents were extracted from the available data for the 20 diets ingested by the 141 subjects included in the analysis. For the 6 diets ingested by the subjects studied in the UCSF General Clinical Research Center, we determined the content of those nutrients either by direct chemical analysis or from diet-composition tables (16). In some of the papers cited, the nutrient content was determined from chemical analysis of the diet ; in others, it was estimated by using specific diet-composition tables cited by the authors .
蛋白质、钾和能量含量的值是从分析中包含的 141 名受试者摄入的 20 种饮食的可用数据中提取的。对于在加州大学旧金山分校综合临床研究中心研究的受试者摄入的 6 种饮食，我们通过直接化学分析或饮食成分表确定了这些营养素的含量 （16）。在引用的一些论文中，营养成分是通过饮食 的化学分析确定的;在其他情况下，它是通过使用作者 引用的特定饮食组成表来估计的。
For 13 diets sufficient information was available for separately estimating the protein contents of the animal and vegetable foods of the diet or by using Agriculture Handbook no. 8 (16) as modified by chemical analyses of certain food items used by the UCSF General Clinical Research Center. For those 13 diets we also estimated sulfur content from the methionine and cystine contents of the listed food items (16). Sulfur content was computed from the formula
对于13种饮食，有足够的信息来单独估计饮食 中动物和植物性食物的蛋白质含量，或者使用农业手册第8（16）号，该手册通过对加州大学旧金山分校综合临床研究中心使用的某些食品进行化学分析而修改。对于这 13 种饮食，我们还从所列食物的蛋氨酸和胱氨酸含量中估计了硫含量 （16）。根据公式计算硫含量
where 149.2 is the molecular weight of methionine and 240.3 that of cystine. For 3 additional diets such estimation was not possible because a detailed listing of food items was lacking, but sulfur contents were specified by the investigators (13). Thus, sulfur contents were available for a total of 16 diets.
其中 149.2 是蛋氨酸的分子量，240.3 是胱氨酸的分子量。对于另外 3 种饮食，由于缺乏详细的食物清单，因此无法进行这种估计，但研究人员指定了硫含量 （13）。因此，总共有16种饮食的硫含量。
For 16 diets, sufficient data were available to calculate the difference between the inorganic cations and anions of the diet, namely , expressed in milliequivalents. A positive value for the difference (ie, an excess of inorganic cations, or an anion gap) implies that the diet contains an excess of organic anions (eg, citrate) relative to organic cations (eg, lysine), which fills the anion gap. Because metabolism of organic anions yields base equivalents and that of organic cations yields acid equivalents, this difference can be taken as the potential base of the diet. Negative values of potential base are theoretically possible but are uncommon for ordinary diets. Because the and contents of table salt are equal and because the contents of the 2 ions in natural foods are equal on average (17), we omitted the mutually canceling terms and in the calculation. That allowed calculation of potential base for diets in which the content was not specified.
对于16种日粮，有足够的数据来计算日粮中无机阳离子和阴离子之间的差异，即 以毫当量表示。差异的正值（即无机阳离子过量或阴离子间隙）意味着饮食中含有相对于有机阳离子（如赖氨酸）过量的有机阴离子（例如柠檬酸盐），有机阳离子填充了阴离子间隙。由于有机阴离子的代谢产生碱当量，而有机阳离子的代谢产生酸当量，因此这种差异可以作为饮食的潜在基础。理论上，潜在碱的负值是可能的，但在普通饮食中并不常见。由于食盐 的 和 含量相等，并且天然食品中 2 个离子的含量平均相等 （17），因此我们在计算中省略了相互抵消项 和 。这样就可以计算出未指定 含量的饮食的潜在基础。

Data analysis 数据分析

For analysis of the relation of diet protein content, potassium content, and NEAP, the values for those variables were first collected into a master database comprising the individual values of those variables available for each subject. For the articles that failed to report values for individual subjects , only the subject-group average was included. As a result, the master database contains individual subject data for 56 subjects and subject-group average data for 85 subjects, yielding a total of 73 data points. From the master database, a working database was developed comprising the average values of the selected variables for each group of subjects ingesting each diet, yielding a total of 20 data points, 1 for each of the 20 diets.
为了分析饮食蛋白质含量、钾含量和NEAP之间的关系，首先将这些变量的值收集到一个主数据库中，该数据库包含每个受试者可用的这些变量的单个值。对于未能报告单个受试者 值的文章，仅包括受试者组平均值。因此，主数据库包含 56 名受试者的个体受试者数据和 85 名受试者的受试者组平均数据，总共产生 73 个数据点。从主数据库中，开发了一个工作数据库，其中包含摄入每种饮食的每组受试者的选定变量的平均值，总共产生 20 个数据点，20 种饮食中每组 1 个。
Because NEAP for subjects eating the same diet varies depending on the quantity ingested, most of the data analysis was carried out on values of NEAP adjusted to a standard quantity of diet ingested, expressed as energy intake, namely 10460 , a convenient reference value and one that was close to the average energy intake [10033 kJ/d (2398 kcal/d)] of the 141 subjects studied.
由于吃相同饮食的受试者的 NEAP 因摄入量而异，因此大多数数据分析是针对调整为摄入的标准饮食量的 NEAP 值进行的，表示为能量摄入量，即 10460 ，一个方便的参考值，并且接近 141 名研究受试者的平均能量摄入量 [10033 kJ/d （2398 kcal/d）]。

Laboratory analysis 实验室分析

RNAE, expressed as , was determined as the sum of the excretion rates of titratable acid and ammonium minus that of
RNAE，表示为 ，被确定为可滴定酸和铵的排泄率之和减去
TABLE 1 表1
Mean protein, potassium, and renal net acid excretion data for each
每种 药物的平均蛋白质、钾和肾脏净酸排泄数据
Diet
code
Energy
intake
Potassium
intake
Protein
intake
RNAE Pro/K
1 7113 80 75 12 0.94
2 9121 133 60 24 0.45
3 7113 74 75 26 1.01
4 9293 99 74 31 0.75
5 7657 40 39 32 0.96
6 8736 72 85 37 1.19
7 7113 72 75 39 1.04
8 13104 56 60 40 1.06
9 13598 75 90 45 1.21
10 10962 75 78 47 1.04
11 13765 93 114 53 1.23
12 15803 73 93 62 1.27
13 10343 85 99 64 1.17
14 10209 101 95 70 0.94
15 12636 98 100 70 1.02
16 8364 41 90 71 2.19
17 8527 58 96 75 1.64
18 9247 40 79 102 1.98
19 14891 124 193 115 1.56
20 9037 54 120 136 2.21
RNAE, renal net acid excretion; Pro, protein in g/d; K, potassium in ; Pro/K, ratio of Pro to K.
RNAE，肾净酸排泄;Pro，蛋白质，单位：g/d;K， 钾含量 ;Pro/K，Pro与K的比值。
bicarbonate. In our laboratory, the urine bicarbonate concentration was calculated from the measured values of urine and carbon dioxide content by use of the Henderson-Hasselbach equation, for which the solubility coefficient of carbon dioxide was taken as 0.0309 and was corrected for ionic strength: , where and concentrations are expressed in Eq/L. Urine total carbon dioxide content was determined by thermal conductivity. Titratable acid concentration was determined by titration, and urine ammonium concentration was determined by the phenol method (18). In the articles from the literature surveys, RNAE was calculated as described above from component assays as described in the respective articles (5, 11-15).
碳酸氢盐。在我们的实验室中，尿碳酸氢盐浓度是使用 Henderson-Hasselbach 方程根据尿液 和二氧化碳含量的测量值计算得出的，其中二氧化碳的溶解系数为 0.0309，并 针对离子强度进行校正： ，其中 和 浓度以方程/L 表示。 尿液总二氧化碳含量由导热系数确定。通过滴定法测定可滴定酸浓度，通过苯酚法测定尿铵浓度 （18）。在文献调查的文章中，如上所述，从相应文章中描述的组分测定中计算 RNAE （5， 11-15）。

Units of measure 计量单位

Charged species are expressed in milliequivalents to allow calculation (by algebraic summation) of charge balances (ie, estimation of cation or anion gaps) necessary for conclusions about dietary potential acid or base content. The number of milliequivalents of a charged species is equal to the number of millimoles multiplied by the charge valance of the species. There is no SI unit for net acid; the standard units of milliequivalents are used throughout.
带电物质以毫当量表示，以便计算（通过代数求和）电荷平衡（即阳离子或阴离子间隙的估计），以得出有关膳食潜在酸或碱含量的结论。带电物质的毫当量数等于毫摩尔数乘以该物质的电荷价。净酸没有国际单位制单位;自始至终都使用毫当量的标准单位。

Statistical analysis 统计分析

Statistical analyses were carried out with SIGMASTAT (Jandel Corp, San Rafael, CA).
与SIGMASTAT（Jandel Corp，San Rafael，CA）一起进行统计分析。

RESULTS 结果

The subject-group averages for the 20 diets analyzed are summarized in Table 1. In the 20 diets, protein content ranged from 39 to , potassium content from 40 to , energy
表1总结了所分析的20种饮食的受试者组平均值。在20种饮食中，蛋白质含量从39到 40不等，钾含量从40到 40不等
TABLE 2 表2
Regression analyses for 20 diets
20种饮食 的回归分析
Potassium Protein Pro/K
RNAE
-0.440 - - - - -
-0.374 - - 0.14 -0.37 NS
NS - - - — -
RNAE
— 0.792 - 一 - -
- 0.597 - 0.36 0.69 0.006
— - - — -
RNAE
-0.614 -0.937 - — — —
-0.522 -0.707 - 0.62 —
- - - -
RNAE
- - 62.1 0.71 0.84
- - - - -
, nonstandardized regression coefficient; B, standardized regression coefficient; horizontal rows of values indicate the levels of significance of the regression coefficients. Protein (Pro, in g) and potassium (mEq) are in units/d per (2500 kcal) diet. RNAE, renal net acid excretion.
、非标准化回归系数;B， 标准化回归系数; 值的水平行表示回归系数的显著性水平。蛋白质（Pro，单位：g）和钾（mEq）以单位/天为单位 （2500 kcal）饮食。RNAE，肾净酸排泄。
content from 7113 to (1700 to ), and RNAE from 12 to . Expressed in units per day per diet ingested, the corresponding ranges were similar: protein content, 48-139 g; potassium content, 45-153 mEq; and RNAE, 18-157 mEq. The energy-adjusted values of both protein and potassium contents were normally distributed (KolmogorovSmirnov test). The ratio of protein to potassium content varied over a 5 -fold range, from 0.45 to . There was no significant correlation between protein content and potassium content among diets.
含量从 7113 到 （1700 到 ），RNAE 从 12 到 。以每天摄入的每种 饮食的单位表示，相应的范围相似：蛋白质含量，48-139克;钾含量，45-153 mEq;和 RNAE，18-157 mEq。蛋白质和钾含量的能量调整值均呈正态分布（KolmogorovSmirnov检验）。蛋白质与钾含量的比例变化为5倍，从0.45到 。饮食中蛋白质含量和钾含量之间没有显著相关性。
By multiple linear regression analysis of the energy-adjusted variables (Table 2), protein content and potassium content were independent predictors of RNAE (Figure 1; ):
通过能量调整变量的多元线性回归分析（表2），蛋白质含量和钾含量是RNAE的独立预测因子（图1; ）：
RNAE Pro
RNAE 专业版
where Pro is protein.
其中 Pro 是蛋白质。
That is, the regression coefficients of both protein and potassium were significantly different from zero, and 0.003 , respectively. The regression coefficient of protein was positive and that of potassium was negative, suggesting that increasing protein content increases RNAE and increasing potassium content decreases it. Differences in protein content had a slightly greater (1.4-fold) effect on RNAE than did differences in potassium content, as indicated by the values of their respective standardized regression coefficients, namely, 0.71 compared with -0.52 (Table 2).
也就是说，蛋白质和钾的回归系数分别从零 和 0.003显著不同。蛋白质的回归系数为正，钾的回归系数为负，表明蛋白质含量增加可增加RNAE，增加钾含量可降低RNAE。蛋白质含量的差异对RNAE的影响略大于钾含量的差异（1.4倍），如其各自标准化回归系数的值所示，即0.71与-0.52（表2）。
Similar results were obtained when the regression was performed without adjusting the 3 variables to a constant energy content :
在不将 3 个变量调整为恒定能量含量 的情况下进行回归时，也获得了类似的结果：
RNAE Pro
RNAE 专业版
Both regression coefficients were significantly different from zero, and , respectively. Differences in protein content had a 1.9-fold greater effect on RNAE than did differences in potassium content, as indicated by the values of their respective standardized regression coefficients, 0.88 compared with -0.46 .
两个回归系数分别与零 和 、 显著不同。蛋白质含量差异对RNAE的影响是钾含量差异的1.9倍，如其各自的标准化回归系数值所示，0.88与-0.46相比。
FIGURE 1. The relation between steady state renal net acid excretion (RNAE) and dietary contents of protein (Pro) and potassium for 20 different whole-food diets. RNAE Pro . The regression coefficients of both Pro and were significantly different from zero, and , respectively.
图 1.20 种不同全食物饮食的稳态肾净酸排泄 （RNAE） 与蛋白质 （Pro） 和钾膳食含量之间的关系。RNAE 专业 版。Pro 和 的回归系数分别与零 和 、 显著不同。
Because protein and potassium contents were directionally opposing independent predictors of RNAE by multiple linear regression analysis, the ratio of protein to potassium content in the diet should provide a good linear index of RNAE. Thus, by linear regression analysis, RNAE (mEq/d 10460 kJ diet) correlated significantly with Pro/K (g/mEq) (Table 2, Figure 2; :
由于蛋白质和钾含量在多元线性回归分析中是 RNAE 的方向性相反的独立预测因子，因此饮食中蛋白质与钾含量的比率应提供良好的 RNAE 线性指数。因此，通过线性回归分析，RNAE（mEq/d 10460 kJ饮食）与Pro/K（g/mEq）显著相关（表2，图2; ：
Similar results were obtained when the variables were not energy adjusted :
当变量未进行能量调整 时，也获得了类似的结果：
For the subset of 13 diets for which data for both animal and vegetable foods were available, RNAE was highly correlated with animal protein content but not with vegetable protein content. The range of variation of vegetable protein content ( diet; minimum and maximum: 18 and ] was much less than that of animal protein content (104 g/10460 kJ of diet; minimum and maximum: 13 and ), a nearly 3-fold difference. Expressing vegetable food intake in terms of energy ingested likewise did not give a significant correlation with RNAE. The ratio of animal to vegetable protein content of the 13 diets varied from 0.23 to 4.31, a nearly 20 -fold range, and the individual values for animal and vegetable protein contents varied independently for the diets, as did animal and vegetable energy ingested.
对于可获得动物和植物性食物数据的 13 种饮食的子集，RNAE 与动物蛋白含量 高度相关，但与植物蛋白含量无关。植物蛋白含量的变化范围（ 日粮;最小值和最大值：18和 ]远小于动物蛋白含量（104 g/10460 kJ日粮;最小值和最大值：13和 ），相差近3倍。同样，以摄入的能量来表示植物性食物摄入量与RNAE没有显着相关性。13种日粮的动植物蛋白含量比例从0.23到4.31不等，相差近20倍，动物和植物蛋白含量的个体值因日粮而异，动物和植物蛋白含量的摄入量也随日粮的变化而变化。
In the subset of 16 diets for which data for sulfur content were available, RNAE correlated directly with sulfur content ( ; Table 3). Sulfur content in turn correlated directly with total protein ( diets; diets) and with animal protein ( diets). (Correlations for both and diets are reported to allow comparison of the relation of sulfur content with both total and animal protein contents because total protein content was known for all diets but animal protein content for only 13 diets.)
在有硫含量数据的16种饮食中，RNAE与硫含量直接相关（ ;表3）。硫含量反过来又与总蛋白质（ 饮食; 饮食）和动物蛋白（ 饮食）。（据报道，两者 和 饮食的相关性允许比较硫含量与总蛋白和动物蛋白含量的关系，因为所有饮食的总蛋白质含量都是已知的，但只有 13 种饮食的动物蛋白含量。
In the subset of 16 diets for which data were available to calculate potential base content, potential base varied from -2 to diet. RNAE correlated inversely with potential base ( ), and potential base in turn correlated directly with potassium content . By multiple regression analysis, potential base and protein content together accounted for of the variation in RNAE ( diets; Table 3). By comparison, for this same subset of diets, protein and potassium content accounted for of
在16种饮食的子集中，有数据可以计算潜在的碱含量，潜在的碱从-2到 饮食不等。RNAE与电位碱基（ ）成反比，而电位碱基又与钾含量 直接相关。通过多元回归分析，潜在碱基和蛋白质含量共同解释了 RNAE（ 饮食;表3）。相比之下，对于相同的饮食子集，蛋白质和钾含量 占
FIGURE 2. The relation between steady state renal net acid excretion (RNAE) and the ratio of dietary protein (Pro, g/d 10460 kJ) to potassium (mEq/d 10460 kJ) content for 20 different whole-food diets. RNAE Pro .
图2.20 种不同全食饮食的稳态肾净酸排泄 （RNAE） 与膳食蛋白质 （Pro， g/d 10460 kJ） 与钾 （mEq/d 10460 kJ） 含量之比之间的关系。RNAE 专业 版。
TABLE 3 表3
Regression analyses for 16 diets
16种饮食 的回归分析
Potassium Protein Pro/K Potential base 潜在基础 Sulfur
RNAE
-0.519 - — - - - 0.19 -0.43 NS
NS - - - - - - - -
RNAE
- 0.904 - - - - 0.37 0.61 0.013
- 0.013 - - - - - - -
RNAE
-0.632 1.014 — - - - — — -
-0.530 0.681 - - - - 0.64 -
- - - - - — —
RNAE
- 0.794 - -0.557 - - - - -
- 0.534 - -0.574 - - 0.69 -
- - - - - - -
RNAE
- — 62.7 - - - 0.73 0.85
- — - - - - - -
RNAE
— — — -0.624 - - 0.41 -0.64
- — — — - - - -
RNAE
- - - - 1.24 - 0.56 0.75
- - - - - - - -
RNAE
- - - - - 0.605 0.68 0.82
- - — - - - - -
RNAE
— - — -0.429 0.994 - - — -
— — — -0.442 0.602 — 0.74 -
- - — 0.002 - - — -
the variation in RNAE . Both potassium and potential base contents varied independently of protein content in diets.
RNAE的变异 。钾和潜在碱含量的变化与饮食中的蛋白质含量无关。
By multiple regression analyses, sulfur and potential base contents together accounted for of the variation in RNAE among diets ( diets; Table 3 ). By comparison, for those same 16 diets, protein and potassium contents together accounted for of the variation in RNAE . Differences in sulfur content had a slightly greater (1.4-fold) effect on RNAE than did differences in potential base content, as indicated by the ratio of their respective standardized regression coefficients, 0.60 and -0.44 , respectively. That 1.4 -fold greater effect of sulfur compared with potential base on RNAE is in accord with a 1.3-fold greater effect of total protein compared with potassium for the same diets (standardized regression coefficients, 0.68 and -0.53 , respectively; Table 3 ). Sulfur and potential base contents varied independently among diets.
通过多元回归分析，硫和潜在碱含量共同解释了 日粮间RNAE的变化（ 日粮;表3）。相比之下，对于相同的 16 种饮食，蛋白质和钾含量共同解释了 RNAE 的变化 。硫含量的差异对RNAE的影响略大于潜在碱基含量的差异（1.4倍），如它们各自的标准化回归系数之比分别为0.60和-0.44所示。在相同饮食中，硫与潜在碱基相比，对RNAE的影响高出1.4倍，而总蛋白对钾的影响高出1.3倍（标准化回归系数分别为0.68和-0.53;表3）。硫和潜在碱含量因日粮而异。
By simple regression analysis, we tested whether the difference between sulfur (acid precursors) and potential base (base precursors) predicted RNAE. Sulfur minus potential base correlated directly with RNAE and accounted for of the variation in RNAE among diets diets; Table 3, Figure 3). For those same 16 diets, protein and potassium correlated directly with RNAE and accounted for of the variation in RNAE among diets . Pro/K and sulfur minus potential base were highly correlated .
通过简单的回归分析，我们测试了硫（酸性前体）和潜在碱（碱基前体）之间的差异是否预测了RNAE。硫减去潜在碱与RNAE直接相关，并解释了 日 粮之间RNAE的差异;表3，图3）。对于相同的 16 种饮食，蛋白质和钾与 RNAE 直接相关，并解释了 饮食之间 RNAE 的差异 。Pro/K和硫减去势基高度相关 。
Of the 20 diets studied, magnesium content was known for 18 diets. For those diets, in diet, magnesium content was , potassium content was , and the sum of magnesium plus potassium was ; magnesium content represented of the total of magnesium plus potassium. Incorporating magnesium content into the data analysis did not improve the overall ability to predict RNAE. By multiple regression analysis with protein content and total potassium and magnesium content as the 2 independent variables, of the variation in RNAE among diets was accounted for , diets). For those same 18 diets, protein and potassium contents alone accounted for of the variation in RNAE ( 0.001 ). The ratio of protein content to total content of potassium plus magnesium (Pro/[K + Mg]) correlated less well with RNAE than did Pro/K alone diets . Substitution of magnesium for potassium in the multiple regression model with protein did not improve ( 0.57 compared with 0.63 ), and the ratio of protein to magnesium did not correlate significantly with RNAE ( ).
在所研究的 20 种饮食中，已知 18 种饮食的镁含量。对于这些饮食，在饮食中 ，镁含量为 ，钾含量为 ，镁加钾的总和为 ;镁含量代表 镁加钾的总和。将镁含量纳入数据分析并没有提高预测RNAE的整体能力。通过以蛋白质含量和总钾镁含量为2个自变量的多元回归分析， 考虑了日粮间RNAE的差异 。 对于这18种饮食，仅蛋白质和钾含量就解释了 RNAE的变化（ 0.001）。蛋白质含量与钾加镁总含量的比率 （Pro/[K + Mg]） 与 RNAE 的相关性低于单独 Pro/K 饮食 。在蛋白质的多元回归模型中，镁对钾的替代没有改善 （0.57 对 0.63），蛋白质与镁的比率与 RNAE 没有显著相关性 （ ）。

DISCUSSION 讨论

The results here indicate that in normal subjects steady state RNAE is highly correlated with the ratio of the dietary content of total protein to potassium ( , 2 components of the diet for which quantitative information is widely available
这里的结果表明，在正常受试者中，稳态RNAE与总蛋白质与钾的膳食含量之比高度相关（ ，饮食中定量信息广泛可用的2种成分
FIGURE 3. Comparison of the predictive ability of dietary sulfur minus potential base and the ratio of protein to potassium on steady state renal net acid excretion (RNAE) for the 16 of 20 diets studied for which sulfur and potential base contents were known. Protein is expressed as ; RNAE, potassium, sulfur, and potential base are expressed as .
图3.比较已知硫和潜在碱含量的 20 种饮食中的 16 种膳食硫减去潜在碱的预测能力以及蛋白质与钾对稳态肾净酸排泄 （RNAE） 的比率。蛋白质表示为 ;RNAE、钾、硫和电位碱表示为 。
in standard food-composition tables. Given that steady state RNAE in normal subjects corresponds closely with the dietdependent rate of endogenous acid production (5), these results provide a relatively simple and reliable method for determining and controlling the net acid load of the diet.
在标准食品成分表中。鉴于正常受试者的稳态 RNAE 与内源性酸产生的饮食依赖性速率密切相关 （5），这些结果为确定和控制饮食的净酸负荷提供了一种相对简单可靠的方法。
In studying the acid-base effects of diet, most workers use steady state RNAE to estimate the net acid load of the diet (ie, the net rate of NEAP) . In fact, when endogenous acid production is measured in normal subjects by methods that are independent of measurement of RNAE, concomitantly measured RNAE and endogenous acid production are strongly and directly correlated . Accordingly, in normal subjects in a steady state, RNAE is a reliable predictor of the diet net acid load. Indeed, RNAE may be a better index of diet net acid load than that provided by independent measurement of net endogenous acid production because the latter inherits the cumulative errors of the measurement of multiple inorganic constituents of the diet and stool and of organic anions excreted in the urine .
在研究饮食的酸碱效应时，大多数工人使用稳态RNAE来估计饮食的净酸负荷（即NEAP的净速率）。 事实上，当通过独立于RNAE测量的方法测量正常受试者的内源性酸产生时，同时测量的RNAE和内源性酸的产生是强烈而直接相关的 。因此，在处于稳定状态的正常受试者中，RNAE是饮食净酸负荷的可靠预测因子。事实上，RNAE可能比独立测量内源性酸净产量所提供的指标更好，因为后者继承了饮食和粪便中多种无机成分以及尿液中排泄的有机阴离子的测量的累积误差 。
In the present study, using RNAE as an index of endogenous acid production, we tested whether the net acid load of the diet could be predicted simply from the nutrient composition of the diet. We focused on dietary protein and potassium contents because the rate of sulfuric acid production from protein metabolism and the rate of bicarbonate generation from metabolism of intestinally absorbed potassium salts of organic acids are major and highly variable components of the net endogenous acid production rate (6). The only other quantitatively significant component of the endogenous acid production rate is organic acid production (eg, lactic acid), reflecting incomplete combustion of carbohydrate and fat to carbon dioxide and water (6). Accordingly, differences in organic acid production resulting from the different diets studied might account for some of the unexplained variation in RNAE among diets with similar ratios of protein to potassium content (Figure 2). That is, at any given protein-to-potassium ratio, the observed differences in RNAE might be due in part to differences in diet-induced organic acid production. In normal subjects, however, organic acid production varies little among diets, even when the diets are otherwise sufficiently different to yield a 17 -fold difference in endogenous acid production over a wide range (7-122 mEq/d) similar to that observed here (11).
在本研究中，使用RNAE作为内源性酸产生的指标，我们测试了是否可以简单地从饮食的营养成分来预测饮食的净酸负荷。我们关注膳食蛋白质和钾含量，因为蛋白质代谢产生的硫酸速率和肠道吸收的有机酸钾盐代谢产生的碳酸氢盐速率是净内源性酸产生速率的主要且高度可变的成分 （6）。内源性酸产生速率的唯一其他定量重要成分是有机酸产生（例如，乳酸），反映了碳水化合物和脂肪对二氧化碳和水的不完全燃烧（6）。因此，所研究的不同饮食导致的有机酸产生的差异可能是蛋白质与钾含量比例相似的饮食中RNAE的一些无法解释的差异的原因（图2）。也就是说，在任何给定的蛋白质与钾的比例下，观察到的RNAE差异可能部分是由于饮食诱导的有机酸产生的差异。然而，在正常受试者中，有机酸的产生在饮食中变化不大，即使饮食在其他方面差异很大，在很宽的范围内（7-122 mmol/d）产生17倍的内源性酸产生差异，类似于这里观察到的（11）。
The validity of using diet protein content as a surrogate for sulfuric acid production is supported by the finding that urinary sulfate excretion correlated strongly and directly with total protein content diets; diets) and with animal protein content , diets). The correlation with animal protein content was only marginally stronger than with total protein content ( compared with 0.88 ), and the slopes of the regression lines were identical . Accordingly, for the purpose of predicting the net acid load of the diet from the protein-to-potassium ratio of the diet, it seems that either total protein content or animal protein content can be used. Indeed, for the subset of 13 diets in which animal protein content was available, the correlation of RNAE with the ratio of animal protein to potassium was only marginally greater than that with the ratio of total protein to potassium ( compared with 0.86 ).
使用日粮蛋白质含量作为硫酸生产的替代物的有效性得到了尿硫酸排泄与总蛋白质含量 日粮强烈直接相关的发现的支持; 日粮）和动物蛋白含量 ， 日粮）。与动物蛋白含量的相关性仅略强于与总蛋白含量的相关性（ 与0.88相比），回归线的斜率相同 。因此，为了从日粮的蛋白质与钾的比率预测日粮的净酸负荷，似乎可以使用总蛋白质含量或动物蛋白含量。事实上，对于13种动物蛋白含量可用的饮食子集，RNAE与动物蛋白与钾的比率的相关性仅略高于与总蛋白质与钾的比率的相关性（ 相比之下为0.86）。
Although urinary sulfur excretion correlated both with animal protein content and with total protein content, it did not correlate significantly with vegetable protein content. That apparent lack of correlation may partly reflect the substantially narrower range of variation of vegetable protein content compared with animal protein content in the diets analyzed in this study (range of protein contents for vegetable and animal content, respectively, 18-57 and 13-117 g/10460 kJ of diet; diets). It may also partly reflect the greater variation in the sulfur content of veg-
虽然尿硫排泄与动物蛋白含量和总蛋白含量相关，但与植物蛋白含量无显著相关性。这种明显的相关性缺乏可能部分反映了本研究分析的日粮中植物蛋白含量与动物蛋白含量相比变化范围要小得多（蔬菜和动物含量的蛋白质含量范围分别为 18-57 和 13-117 g/10460 kJ; 饮食）。它也可能部分反映出蔬菜硫含量的较大变化。
etable proteins compared with that of animal proteins (ie, sulfur content per unit protein content), a finding that is evident from food-composition tables that report sulfur content (20).
可食用蛋白质与动物蛋白质的比较（即每单位蛋白质含量的硫含量），这一发现从报告硫含量的食物成分表中可以明显看出（20）。
Because the sulfur content of vegetable proteins is much more variable than that of animals proteins (20), it may seem surprising that the ratio of total protein (animal plus vegetable) to potassium was such a good predictor of the diet net acid load (Figure 2). Indeed, the greater variability of sulfur content in vegetable compared with animal protein is evident specifically when sulfur content is computed per unit potassium content (20). As noted above, however, differences in vegetable protein content among the diets considered here were substantially less than the corresponding differences in animal protein content, so vegetable protein content would presumably have less weight as a determinant of the overall variability in the diet net acid load. Most important, however, for the estimation of RNAE, the data clearly show that RNAE is highly predictable from the ratio of total protein to potassium content over a wide range of ratios of animal to vegetable protein content. In fact, the ratio of animal to vegetable protein content of the studied diets varied over a nearly 20 -fold range, from 0.23 to 4.31; Nevertheless, additional studies with larger numbers of different diets will be needed to determine whether total protein-to-potassium ratio remains generally predictive of the diet net acid load.
由于植物蛋白的硫含量比动物蛋白的硫含量变化大得多（20），因此总蛋白（动物加植物）与钾的比率是饮食净酸负荷的良好预测指标，这似乎令人惊讶（图2）。事实上，与动物蛋白相比，植物中硫含量的更大变异性在计算每单位钾含量时尤为明显（20）。然而，如上所述，这里考虑的日粮之间植物蛋白含量的差异大大小于动物蛋白含量的相应差异，因此植物蛋白含量作为日粮净酸负荷总体变异性的决定因素的权重可能较小。然而，最重要的是，对于RNAE的估计，数据清楚地表明，在动物蛋白和植物蛋白含量的广泛比例范围内，RNAE从总蛋白与钾含量的比率是高度可预测的。事实上，所研究的日粮中动物蛋白与植物蛋白含量的比例变化了近20倍，从0.23到4.31;然而，还需要对大量不同饮食进行额外的研究，以确定总蛋白质与钾的比率是否仍然普遍预测饮食净酸负荷。
Because the net rate of endogenous acid production is the difference between the rates of acid and base production, we also sought a marker for the content of base precursors in the diet. Dietary base precursors are predominantly organic anions, such as citrate, succinate, and other conjugate bases of carboxylic acids, which are predominantly intracellular constituents that the body metabolizes to bicarbonate . Organic and inorganic cations both balance the charge of these anions. Organic cations, such as lysine and arginine, however, yield acid equivalents on metabolism and thereby reduce the net base load resulting from metabolism of organic anions (6, 8). [In ordinary diets, the content of organic anions exceeds that of organic cations .] Accordingly, the effective base load from organic anions is from the metabolism of that quantity of organic anion with charge balanced by inorganic cations (6). As the predominant intracellular inorganic cation, potassium is the major source of inorganic counter-ion for organic anions. Therefore, we used dietary potassium content as an index of the content of base precursors in the diet.
由于内源性酸产生的净速率是酸和碱生成速率之间的差值，因此我们还寻求饮食中碱前体含量的标志物。膳食基础前体主要是有机阴离子，如柠檬酸盐、琥珀酸盐和其他羧酸的共轭碱基，这些碱基主要是细胞内成分，人体将其代谢为碳酸 氢盐。有机阳离子和无机阳离子都平衡这些阴离子的电荷。然而，有机阳离子（如赖氨酸和精氨酸）在代谢时产生酸当量，从而降低有机阴离子代谢产生的净碱负荷 （6， 8）。[在普通饮食中，有机阴离子的含量超过有机阳离子 的含量。因此，有机阴离子的有效基载量来自该量的有机阴离子的代谢，其电荷由无机阳离子平衡 （6）。钾作为主要的细胞内无机阳离子，是有机阴离子无机反离子的主要来源。因此，我们使用膳食钾含量作为膳食中碱前体含量的指标。
Indeed, with protein content held constant, potassium content was a significant inverse predictor of RNAE (Table 2 , Figure 1). That is, as potassium content increased for any given protein content, RNAE decreased (Figure 1). Over their respective ranges of variation among diets, potassium content had about one-third less quantitative effect on RNAE than did protein content (the protein effect was 1.4 times greater than the potassium effect). However, together, as independent predictors in a regression model, protein and potassium content accounted for (Table 2, Figure 1) and as the ratio of protein to potassium content accounted for of the variation in RNAE among diets (Table 2, Figure 2).
事实上，在蛋白质含量保持不变的情况下，钾含量是RNAE的重要反向预测因子 （表2，图1）。也就是说，对于任何给定的蛋白质含量，随着钾含量的增加，RNAE会降低（图1）。在饮食中各自的变异范围内，钾含量对RNAE的定量影响比蛋白质含量低约三分之一（蛋白质效应是钾效应的1.4倍）。然而，作为回归模型中的独立预测因子，蛋白质和钾含量 占了一起（表2，图1），蛋白质与钾含量的比率解释了 饮食中RNAE的变化（表2，图2）。
Because cells are rich in magnesium as well as potassium, we tested whether inclusion of diet magnesium content in the analysis would improve the ability to predict RNAE from protein and potassium content. Magnesium content averaged of potassium content, and the 2 were highly correlated . Inclusion of magnesium content in the mul- tiple regression model with protein and potassium decreased the unaccounted variability in RNAE by ; in the simple regression model of RNAE against Pro/K, inclusion of magnesium, by using Pro/[K instead of Pro/ , actually increased the unaccounted variability in RNAE (by 10%). Thus, consideration of diet magnesium content little improved, or worsened, the ability to predict RNAE from protein and potassium content. Substitution of magnesium for potassium in the regression models (ie, using protein and magnesium only) also worsened the ability to predict RNAE.
由于细胞富含镁和钾，我们测试了在分析中加入饮食镁含量是否会提高从蛋白质和钾含量预测 RNAE 的能力。镁含量与钾含量的平均 值，两者高度相关 。在蛋白质和钾的多重回归模型中加入镁含量可降低 RNAE 中无法解释的变异性;在 RNAE 与 Pro/K 的简单回归模型中，通过使用 Pro/[K 而不是 Pro/ 来包含镁，实际上增加了 RNAE 中无法解释的变异性（增加了 10%）。因此，考虑饮食中的镁含量几乎没有改善或恶化从蛋白质和钾含量预测RNAE的能力。在回归模型中用镁代替钾（即仅使用蛋白质和镁）也恶化了预测RNAE的能力。
Several methods for predicting or estimating the net acid load of the diet from its nutrient composition have been reported. Remer and Manz (11) and their colleagues developed a physiologically based calculation model based on 1) the estimated contents of all of the major inorganic components of the diet (sodium, potassium, calcium, magnesium, chloride, and phosphorus) and reference values for their fractional intestinal absorption; 2) the estimated total protein content of the diet, its estimated fractional intestinal absorption, and the estimated average sulfur content of protein from methionine and cystine; and 3) the assumption of a diet-independent rate of organic acid production. Remer and Manz (11) and Manz et al (12) tested the predictive ability of this model for several synthetic and formula diets and for 3 whole-food diets differing in protein and other nutrients. For the 3 whole-food diets, the predicted diet acid loads underestimated measured RNAE, the differences ranging from 8 to , or from to , depending on the size of the net acid load (11).
已经报道了几种根据其营养成分预测或估计饮食净酸负荷的方法。Remer 和 Manz （11） 及其同事开发了一个基于生理学的计算模型，该模型基于 1） 饮食中所有主要无机成分（钠、钾、钙、镁、氯化物和磷）的估计含量及其肠道吸收分数的参考值;2）估计的饮食总蛋白质含量，其估计的肠道吸收分数，以及蛋氨酸和胱氨酸蛋白质的估计平均硫含量;3）假设有机酸的产生率与饮食无关。Remer 和 Manz （11） 以及 Manz 等人 （12） 测试了该模型对几种合成和配方饮食以及 3 种蛋白质和其他营养素不同的全食物饮食的预测能力。对于 3 种全食物饮食，预测的饮食酸负荷低估了测量的 RNAE，差异范围从 8 到 ，或从 到 ，具体取决于净酸负荷的大小 （11）。
We compared the methods for estimating RNAE by using the simpler models that we developed in this report, which depend on knowing only the protein and potassium content of the diet, with the more complex model of Remer and Manz (11), which requires a more detailed inventory of diet composition. Specifically, to compare the 2 predictors, Pro/K and the Remer-Manz multivariable-calculated RNAE, we computed RNAE according to the Remer-Manz model for all of the diets used in the present study for which sufficient data were available in the published reports to permit that computation (11 diets), and we also computed Pro/K for those diets. Pro/K and the Remer-Manz calculated RNAE were highly correlated . With protein and potassium used as independent variables in a multiple regression analysis, the RNAE calculated by the RemerManz model varied directly with protein content and inversely with potassium content , and the multiple correlation coefficient was 0.93 . Thus, most of the RNAE-predictive power of the Remer-Manz model resides in the protein and potassium contents of the diets.
我们比较了使用本报告中开发的更简单的模型来估计RNAE的方法，该模型仅依赖于了解饮食中的蛋白质和钾含量，以及Remer和Manz（11）的更复杂模型，该模型需要更详细的饮食成分清单。具体来说，为了比较 Pro/K 和 Remer-Manz 多变量计算的 RNAE 这两个预测因子，我们根据 Remer-Manz 模型计算了本研究中使用的所有饮食的 RNAE，这些饮食在已发表的报告中有足够的数据来允许进行计算（11 种饮食），我们还计算了这些饮食的 Pro/K。Pro/K 和 Remer-Manz 计算的 RNAE 高度相关 。在多元回归分析中，以蛋白质和钾为自变量，RemerManz模型计算的RNAE与蛋白质含量 呈正比变化，与钾含量 呈反比变化，多重相关系数为0.93。因此，Remer-Manz模型的大部分RNAE预测能力在于饮食中的蛋白质和钾含量。
If the net acid load of whole-food diets can be predicted from their protein and potassium content, then for any large number and variety of individual food items composing such diets, the potential net acid load of the individual food items should correlate highly with their protein and potassium content. That follows because whole-food diets are simply mixtures of a variety of individual food items. Fortunately, it is possible to test for this, because Remer and Manz (19) presented tabular data on the potential net acid load of a large number and variety of individual food items, calculated according to their model, which incorporates all of the major inorganic constituents of the diet plus an estimate of potential sulfuric acid production from protein content. They refer to the potential net acid load of a food item as the PRAL, or potential renal acid load. Using their data for 112 different food items in 10 different categories of foods, we found
如果全食物饮食的净酸负荷可以从其蛋白质和钾含量来预测，那么对于构成这种饮食的任何大量和种类的单个食物，单个食物的潜在净酸负荷应与其蛋白质和钾含量高度相关。这是因为全食物饮食只是各种单独食物的混合物。幸运的是，可以对此进行测试，因为Remer和Manz（19）提供了大量和各种单个食品的潜在净酸负荷的表格数据，这些数据是根据他们的模型计算的，该模型包括饮食中所有主要的无机成分以及蛋白质含量中潜在硫酸产量的估计。他们将食物的潜在净酸负荷称为PRAL，或潜在的肾酸负荷。使用他们对 10 种不同类别食物的 112 种不同食物的数据，我们发现
FIGURE 4. The relation between the potential renal acid load and the ratio of protein to potassium content of 112 of 114 food items for which potassium content was not zero. Tabulated by Remer and Manz (19).
图4.钾含量不为零的 114 种食物中 112 种的潜在肾酸负荷与蛋白质与钾含量之比之间的关系。由 Remer 和 Manz （19） 制成表格。
that PRAL and Pro/K were highly correlated ( , Figure 4). (Two of 114 tabulated food items were omitted because the listed potassium content was zero, which would have yielded infinite values for Pro/K.) As was the case for the 11 whole-food diets discussed in the preceding paragraph, using protein and potassium as independent variables in a multiple regression analysis, RNAE, which is equivalent to PRAL, varied directly with protein content and inversely with potassium content , and the multiple correlation coefficient was 0.93 . Thus, again, most of the RNAEor PRAL-predictive power of the Remer-Manz multiple-variable model resides in only 2 diet constituents, protein and potassium, taken together. In summary, the results of this study indicate that in normal humans eating ordinary whole-food diets, the major determinants of differences in NEAP rate among subjects are differences in the protein and potassium content of the diet and that the absolute rate of net endogenous acid production for a given diet can be predicted simply from knowledge of the diet's protein and potassium content.
PRAL和Pro/K高度相关（ 图4）。（114 种制表食物中有两种被省略了，因为列出的钾含量为零，这将产生 Pro/K 的无限值。与上一段讨论的 11 种全食物饮食一样，在多元回归分析中使用蛋白质和钾作为自变量，相当于 PRAL 的 RNAE 与蛋白质含量 呈直接变化，与钾含量 呈反比变化，多重相关系数为 0.93。因此，同样，Remer-Manz 多变量模型的大部分 RNAE或 PRAL 预测能力仅存在于 2 种饮食成分中，即蛋白质和钾。总之，这项研究的结果表明，在食用普通全食物饮食的正常人中，受试者之间NEAP率差异的主要决定因素是饮食中蛋白质和钾含量的差异，并且给定饮食的净内源性酸产生的绝对速率可以简单地通过对饮食蛋白质和钾含量的了解来预测。
We thank the nursing, dietary, and laboratory staffs of the General Clinical Research Center for their assistance in carrying out these studies.
我们感谢综合临床研究中心的护理、饮食和实验室工作人员在进行这些研究时提供的帮助。

REFERENCES 引用

  1. Sebastian A, Harris ST, Ottaway JH, Todd KM, Morris RC Jr. Improved mineral balance and skeletal metabolism in post- menopausal women treated with potassium bicarbonate. N Engl J Med 1994;330:1776-81.
    Sebastian A， Harris ST， Ottaway JH， Todd KM， Morris RC Jr. 改善接受碳酸氢钾治疗的绝经后妇女的矿物质平衡和骨骼代谢。N Engl J Med 1994;330：1776-81。
  2. Kurtz I, Maher T, Hulter HN, Schambelan M, Sebastian A. Effect of diet on plasma acid-base composition in normal humans. Kidney Int 1983;24:670-80.
    Kurtz I， Maher T， Hulter HN， Schambelan M， Sebastian A. 饮食对正常人血浆酸碱组成的影响。肾脏国际 1983;24：670-80。
  3. Frassetto L, Sebastian A. Age and systemic acid-base equilibrium: analysis of published data. J Gerontol 1996;51A:B91-9.
    Frassetto L， Sebastian A. 年龄和系统酸碱平衡：已发表数据分析。J Gerontol 1996 年;51A：B91-9。
  4. Frassetto L, Morris RC Jr, Sebastian A. Effect of age on blood acidbase composition in adult humans: role of age-related renal functional decline. Am J Physiol 1996;271:1114-22.
    Frassetto L， Morris RC Jr， Sebastian A. 年龄对成人血液酸碱组成的影响：与年龄相关的肾功能下降的作用。美国生理学杂志 1996;271：1114-22。
  5. Lennon EJ, Lemann J Jr, Litzow JR. The effect of diet and stool composition on the net external acid balance of normal subjects. J Clin Invest 1966;45:1601-7.
    列侬 EJ、小莱曼 J、小利佐夫。饮食和粪便成分对正常受试者净外部酸平衡的影响。临床投资杂志 1966;45：1601-7。
  6. Kleinman JG, Lemann J Jr. Acid production. In: Maxwell MH, Kleeman CR, Narins RG, eds. Clinical disorders of fluid and electrolyte metabolism. 4th ed. New York: McGraw Hill, 1987:159-73.
    Kleinman JG， Lemann J Jr. 酸生产。在：Maxwell MH，Kleeman CR，Narins RG，编辑。液体和电解质代谢的临床紊乱。第 4 版。纽约：麦格劳希尔，1987：159-73。
  7. Lindeman RD, Tobin J, Shock NW. Longitudinal studies on the rate of decline in renal function with age. J Am Geriatr Soc 1985; 33:278-85.
    Lindeman RD， Tobin J， Shock NW. 肾功能随年龄下降率的纵向研究。J Am Geriatr Soc 1985 年;33:278-85.
  8. Halperin ML. Metabolism and acid-base physiology. Artif Organs 1982;6:357-62.
    Halperin ML. 代谢和酸碱生理学。艺术器官 1982;6：357-62。
  9. Frassetto L, Morris RC Jr, Sebastian A. Potassium bicarbonate reduces urinary nitrogen excretion in postmenopausal women. J Clin Endocrinol Metab 1997;82:254-9.
    Frassetto L， Morris RC Jr， Sebastian A. 碳酸氢钾可减少绝经后妇女的尿氮排泄。临床内分泌代谢杂志 1997;82：254-9。
  10. Frassetto L, Morris RC Jr, Sebastian A. Potassium bicarbonate increases serum growth hormone concentrations in postmenopausal women. J Am Soc Nephrol 1996;10:1349 (abstr)
    Frassetto L， Morris RC Jr， Sebastian A. 碳酸氢钾可增加绝经后妇女的血清生长激素浓度。J Am Soc Nephrol 1996;10：1349 （abstr）
  11. Remer T, Manz F. Estimation of the renal net acid excretion by adults consuming diets containing variable amounts of protein. Am J Clin Nutr 1994;59:1356-61.
    Remer T， Manz F. 食用含有不同量蛋白质的饮食的成年人对肾脏净酸排泄的估计。美国临床营养杂志 1994;59：1356-61。
  12. Manz F, Remer T, Decher-Spliethoff E, et al. Effects of a high protein intake on renal acid excretion in body builders. Z Ernahrungswiss 1995;34:10-5.
    Manz F、Remer T、Decher-Spliethoff E 等人。高蛋白质摄入对健美运动员肾酸排泄的影响。Z Ernahrungswiss 1995;34：10-5。
  13. Breslau NA, Brinkley L, Hill KD, Pak CYC. Relationship of animal protein-rich diet to kidney stone formation and calcium metabolism. J Clin Endocrinol Metab 1988;66:140-6.
    布雷斯劳 NA、布林克利 L、希尔 KD、帕克 CYC。富含动物蛋白的饮食与肾结石形成和钙代谢的关系。临床内分泌代谢杂志 1988;66：140-6。
  14. Lutz J. Calcium balance and acid-base status of women as affected by increased protein intake and by sodium bicarbonate ingestion. Am J Clin Nutr 1984;39:281-8.
    Lutz J. 受蛋白质摄入量增加和碳酸氢钠摄入影响的女性的钙平衡和酸碱状态。美国临床营养杂志 1984;39：281-8。
  15. Lewis NM, Marcus MSK, Behling AR, Greger JL. Calcium supplements and milk: effects on acid-base balance and on retention of calcium, magnesium, and phosphorus. Am J Clin Nutr 1989;49:527-33.
    刘易斯 NM、马库斯 MSK、贝林 AR、格雷格 JL。钙补充剂和牛奶：对酸碱平衡和钙、镁和磷保留的影响。美国临床营养杂志 1989;49：527-33。
  16. US Department of Agriculture. Agricultural handbook no. 8: composition of foods. Washington, DC: US Government Printing Office, 1997.
    美国农业部。农业手册第8号：食品成分。华盛顿特区：美国政府印刷局，1997 年。
  17. Yarbrough S, Nix L, Katz R, Korn M, Sebastian A. The quantitative distribution of chloride in food and relation to sodium content. J Am Diet Assoc 1988;4:472-5.
    亚伯勒 S、尼克斯 L、卡茨 R、科恩 M、塞巴斯蒂安 A.食物中氯化物的定量分布及其与钠含量的关系。J Am 饮食协会 1988;4：472-5。
  18. De Giorgio J. Nonprotein nitrogenous constituents. In: Henry RJ, Cannon DC, Winkelman JW, eds. Clinical chemistry. Principles and technics. New York: Harper and Row, 1974:522-6.
    De Giorgio J. 非蛋白质含氮成分。在：Henry RJ，Cannon DC，Winkelman JW，编辑临床化学。原理和技术。纽约：Harper and Row，1974：522-6。
  19. Remer T, Manz F. Potential renal acid load of foods and its influence on urine pH. J Am Diet Assoc 1995;95:791-7.
    Remer T， Manz F. 食物的潜在肾酸负荷及其对尿液 pH 值的影响。美国饮食协会 1995;95：791-7。
  20. Holland B, Welch AA, Unwin ID, Buss DH, Paul AA, Southgate DAT. McCance and Widdowson's the composition of foods. 5th ed. Cambridge, UK: The Royal Society of Chemistry, 1991.
    Holland B， Welch AA， Unwin ID， Buss DH， Paul AA， Southgate DAT. McCance 和 Widdowson 的食物成分。第 5 版。英国剑桥：皇家化学学会，1991 年。
  1. From the Department of Medicine and General Clinical Research Center, University of California, San Francisco.
    来自加州大学旧金山分校医学系和普通临床研究中心。
    Supported in part by the General Clinical Research Center, UCSF (grant M01 00079); the National Institutes of Health (grants P01DK 39964 and R01HL47943); the University of California Research Evaluations and Allocation Committee (grant MSC-22); a grant from the UCSF Academic Senate; and gifts from Church & Dwight Co, Inc, and the Emil Mosbacher, Jr, Foundation.
    部分由加州大学旧金山分校综合临床研究中心支持（授予 M01 00079）;美国国立卫生研究院（授予 P01DK 39964 和 R01HL47943）;加州大学研究评估和分配委员会（授予 MSC-22）;加州大学旧金山分校学术参议院的资助;以及来自Church & Dwight Co， Inc和Emil Mosbacher， Jr， Foundation的礼物。
    Address reprint requests to A Sebastian, Box 0126, University of California, San Francisco, CA 94143. E-mail: sebastia@gcrc.ucsf.edu. Received November 7, 1997.
    将重印请求发送至 A Sebastian， Box 0126， University of California， San Francisco， CA 94143。电子邮件：sebastia@gcrc.ucsf.edu。收稿日期： 1997-11-07.
    Accepted for publication February 23, 1998.
    1998年2月23日接受出版。
  2. , nonstandardized regression coefficient; , standardized regression coefficient; horizontal rows of values indicate the levels of significance of the regression coefficients. , potential base, or ; , sulfur; , renal net acid excretion. Protein (Pro, in g), potassium (mEq), (mEq), (mEq), and S-PB (mEq) are in units/d per (2500 kcal) diet.
    、非标准化回归系数; 、标准化回归系数; 值的水平行表示回归系数的显著性水平。 、电位碱基或 ; 硫; ，肾净酸排泄。蛋白质（Pro，单位：g）、钾（mEq）、 （mEq）、 （mEq）和S-PB（mEq）以单位/天为单位 （2500 kcal）饮食。