Ebook The Effects of Differing Levels of Protein Consumption on Renal Function in Young Compared to Older Adults
Diets emphasizing restricted carbohydrate and increased protein intake experienced a resurgence in popularity in the US in the late 1990’s and early 2000’s. While consumer interest in these diets has since begun to wane, a number of recent studies have demonstrated the efficacy of a high protein intake combined with moderate intakes of fat and carbohydrates (30% protein, 20-30% fat, 40-50% carbohydrate) in weight loss, appetite control, and improved blood glucose levels. However, there remains conflicting evidence regarding the impact of a high protein intake on overall kidney health, which extends to acid-base balance and bone health.
An increase in protein intake has been shown to increase renal plasma flow and to increase the glomerular filtration rate (GFR). It is accepted that glomerular hyperfiltration resulting from consumption of a high-protein diet can cause progressive kidney damage in people who already suffer from kidney disease; however there is controversy over the effects of a high-protein (HP) diet in those with healthy kidney functio. Additionally, HP diets produce a marked acid load in the form of excess sulfates from the metabolism of sulfur-containing amino acids. To maintain acid-base homeostasis the kidney increases its excretion of the acid load, and any failure on the part of the kidney to excrete the acid will lead to metabolic acidosis. Because aging is associated with a decline in kidney function, in the form of decreased GFR and decreased ability to excrete acid, examining the effects of a HP diet in older people is of particular interest.
Despite the known effects of HP diets causing glomerular hyperfiltration and the generation of excess acid load, and the reduction in the ability of the kidney to eliminate the excess acid with aging, the effect of high-protein diets on systemic acid base balance in conjunction with kidney function has not been studied in older populations. We hypothesized that short-term exposure to a HP diet would lead to a higher degree of metabolic acidosis in the older age group as a result of decreased renal acid excretion with aging. To test these hypotheses we examined the effect of a HP diet on renal function and acid excretion in both young and older individuals. In this study we determined the effect of a HP diet on kidney function, acid load generation, and systemic acid-base balance in older individuals (55-70 years of age) when compared to younger adults (25-40 years of age).
Contents
Introduction
Methods
- Subject Selection
Study Design
Diet Protocol
Sample Collection
Laboratory Assay Procedures
Calculations
Statistical Analyses
Results
- Demographics
Usual Diet Composition
Experimental Diet Composition
Effects on Renal Function
Effects on Acid-Base Balance
Discussion
Conclusions
References
Tables and Figures
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