Effect of Varying Intake of Protein and Salts on the Composition and Specific Gravity of Urine 1

Miller, Max; Jw, Price; Lp, Longley

doi:10.1172/jci101192

Cited by 14 publications

(4 citation statements)

References 6 publications

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“…Addis and Shevky (10) suggested that healthy persons deprived of water might excrete urine of subnormal specific gravity when their diets contained little salt and protein; however, the differences which they obtained were of questionable statistical significance and were not confirmed by Miller, Price, and Longley (11) or by Addis and Foster (12), who in addition pointed out the fallacy of using specific gravity as a measure of osmolar concentration.…”

Section: Discussionmentioning

confidence: 99%

The Effect of Feeding Protein and Urea on the Renal Concentrating Process 1

Epstein¹,

Kleeman²,

Pursel³

et al. 1957

J. Clin. Invest.

144

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The role of dietary protein in the treatment of renal disease remains a controversial one, in part because the influence of diets high or low in protein upon normal renal function is not completely understood. In the rat much evidence has accumulated that high-protein intakes lead to renal hypertrophy (1-3) and that low-protein diets may be associated with impairment of some renal functions (4). Pullman, Alving, Dern, and Landowne (5) (6), creatinine (7), urea (8), sodium and potassium (9) were also determined. The "t" test of "Student" was used in analyzing the data. Each subject was studied after three days on a LowProtein diet, containing approximately 20 grams of protein per day, and a High-Protein diet, containing 150 to 200 grams of protein per day. The latter was achieved by the use of 100 to 200 grams per day of a high-protein, low-sodium supplement.5 Both diets were approximately isocaloric; in some subjects the low-protein diet consisted chiefly of carbohydrate, in others fat predominated. Two subjects were studied on a Regular diet, containing about 90 gramns of protein per day. Other variations in dietary regimen will be described under Results.RESULTS (Table I) Effect of low-vs. high-protein diets on renal concentrating ability, inulin clearance and urea clearance (Figure 1) Maximum urinary solute concentration and maximum osmolal U/P ratio were invariably higher after three days of a high-protein intake than after a diet low or normal with respect to protein. The increases in maximum urinary osmolality with ingestion of large amounts of protein varied from 87 to 332 mOsm. per K. This occurred in association with an increased basal urinary flow containing from 1.2 to 5 times the quantity of solutes excreted on a low-protein diet. The maximum capacity of the kidneys to reabsorb water free of solute (TmOH2O) was likewise increased by 15 to 50 per cent in five subjects by feeding protein.Inulin clearance was slightly higher in each of five subjects on a high-protein regimen than on a diet low in protein. At the high urine flows obtained during mannitol diuresis, the clearance of 5 Melactin, supplied by E. R. Squibb and Co.635

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Section: Discussionmentioning

confidence: 99%

The Effect of Feeding Protein and Urea on the Renal Concentrating Process 1

Epstein¹,

Kleeman²,

Pursel³

et al. 1957

J. Clin. Invest.

144

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“…We hypothesized that the PRAL of the diet affects urine specific gravity as well as urine pH. It is known that high protein intake, which has a direct influence on diet PRAL, negatively affects hydration by affecting kidney function and leading to increased urine output 14 . In fact, when the other factors affecting hydration are controlled, increased dietary protein intake results in increased urine specific gravity 15 .…”

Section: Discussionmentioning

confidence: 99%

“…It is known that daily protein intake in high quantities, which increases dietary acid load, also increases urinary specific gravity, an indicator of dehydration 14,15 . Since water loss as low as 2% of the body weight adversely affects performance 16 , understanding the factors affecting hydration and monitoring hydration level in athletes is extremely important.…”

Section: Introductionmentioning

confidence: 99%

A comparison of dietary acid load between team, endurance, and strength sports

Turnagöl¹,

Aktitiz

Kuru

et al. 2022

Rev. chil. nutr.

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Purpose: Since the dietary acid load (PRAL) may affect the acid-base balance of the body, there is an increasing interest in its role in sports performance. Typical nutritional requirements of different sports, associated with its physiological demands, might be reflected in the acid load of their diet. Thus, the purpose of this study is to compare the dietary acid load between team, endurance, and strength athletes and to determine the associations between PRAL and hydration status. Methods: Fifty-one healthy recreational male athletes (age: 18-39 yrs) from team, endurance, and strength sports participated in the study. A 3-day food diary was recorded and dietary PRAL values (mEq/day) were calculated. Urine pH and specific gravity were measured. One-way ANOVA with Bonferroni post-hoc analysis and Pearson correlation coefficient (r) were used for data analysis. Results: PRAL in endurance athletes (25.34 mEq/day) was lower compared to team and strength athletes (46.12 and 46.47 mEq/day, respectively) (p= 0.023). Percentage of high PRAL diet (≥15 (mEq/day)) was highest in team sports (89.5%), followed by strength (83.3%) and endurance sports (60%). PRAL was not associated with hydration status. Conclusion: Typical nutritional requirements of sport disciplines are reflected in the PRAL, thus PRAL should be considered when preparing nutritional strategies to improve performance.

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“…Because of their potential to impact urine osmolality [17,18], intakes of fluid (moisture in g/day), sodium (mg/day), and protein (g/day) were assessed with a 24-hour recall method that PLOS ONE is based on the United States Department of Agriculture Automated Multiple Pass Method. Dietary moisture reflects all water intake from foods and beverages.…”

Section: Other Variablesmentioning

confidence: 99%

Differences in urine creatinine and osmolality between black and white Americans after accounting for age, moisture intake, urine volume, and socioeconomic status

Wilson,

Winter,

Burdin

2024

PLoS ONE

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Urine osmolality is used throughout research to determine hydration levels. Prior studies have found black individuals to have elevated urine creatinine and osmolality, but it remains unclear which factors explain these findings. This cross-sectional, observational study sought to understand the relationship of self-reported race to urine creatinine and urine osmolality after accounting for age, socioeconomic status, and fluid intake. Data from 1,386 participants of the 2009–2012 National Health and Nutrition Examination Survey were utilized. Age, poverty-to-income ratio (PIR), urine flow rate (UFR), fluid intake, estimated lean body mass (LBM), urine creatinine, and urine osmolality were measured. In a sex-specific manner, black and white participants were matched on age, dietary moisture, UFR, and PIR. Urine creatinine was greater in black men (171 mg/dL) than white men (150 mg/dL) and greater in black women (147 mg/dL) than white women (108 mg/dL) (p < .001). Similarly, urine osmolality was greater in black women than white women (723 vs. 656 mOsm/kg, p = .001), but no difference was observed between white and black men (737 vs. 731 mOsm/kg, p = .417). Estimated LBM was greater in black men (61.8 kg) and women (45.5 kg) than in white men (58.9 kg) and women (42.2 kg) (p≤.001). The strongest correlate of urine osmolality in all race-sex groups was urine creatinine (Spearman ρ = .68-.75). These results affirm that individuals identifying as black produce higher urine creatinine concentrations and, in women, higher urine osmolality after matching for age, fluid intake, and socioeconomic status. The findings suggest caution when comparing urine hydration markers between racial groups.

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Effect of Varying Intake of Protein and Salts on the Composition and Specific Gravity of Urine 1

Cited by 14 publications

References 6 publications

The Effect of Feeding Protein and Urea on the Renal Concentrating Process 1

The Effect of Feeding Protein and Urea on the Renal Concentrating Process 1

A comparison of dietary acid load between team, endurance, and strength sports

Differences in urine creatinine and osmolality between black and white Americans after accounting for age, moisture intake, urine volume, and socioeconomic status

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