The Influence of Diet on Urinary Risk Factors for Stones in Healthy Subjects and Idiopathic Renal Calcium Stone Formers

Abstract

The daily intake of 103 recurrent idiopathic calcium stone formers and 146 controls was assessed by means of a computer-assisted 24-h dietary record. Timed 24-h urine samples were collected over the same period to assess the relationship between dietary intake of nutrients and urinary risk factors for calcium stones. After standardisation for sex, age and social status a total of 128 subjects underwent final statistical analysis; 64 renal stone formers and 64 controls. Significant increases in the consumption of animal and vegetable protein and purine were identified as the nutritional factors that distinguished renal stone formers from controls. As expected, the daily urinary excretion of calcium and oxalate was higher and the daily urinary excretion of citrate was lower in stone formers than in controls. No difference with respect to daily urinary uric acid excretion was recorded. Daily urinary excretion of calcium was correlated to dietary protein intake while daily urinary oxalate was correlated to dietary vitamin C intake. It was concluded that renal stone formers could be predisposed to stones because of their dietary patterns. A link between the protein content of the diet and urinary calcium was confirmed, but dietary animal protein had a minimal effect on oxalate excretion.

Oxalate: From the Environment to Kidney Stones

“…If the food contains an ample amount (5.2 %) of hydroxyproline, oxalate excretion will increase as the supplementary doses of vitamin B6 increase (81). This fi nding supports the observation of a higher incidence of stones in the meat-consuming individuals (19). A greater amount of consumed meat means more consumed collagen, in which hydroxyproline is one of the main components.…”

“…Although both are rich in oxalate, due to different ratios of soluble and non-soluble oxalate, only turmeric signifi cantly increases urine oxalate and thus represents a potential risk factor for urolithiasis (18). When comparing food consumption with regard to stone formers and nonformers, it has been established that stone formers consume signifi cantly higher amounts of proteins (of both plant and animal origin) and purines (19).…”

Laser-induced breakdown spectroscopy is a reliable method for urinary stone analysis

“…However, the findings of other studies are not consistent with these results. [25,26] Our results indicate that although zinc can be seen as an elemental component of urinary calculi, no conclusion can be reached regarding the relationship of zinc with stone types. We found that zinc can be detected in all stone types containing uric acid and struvite, which are non-calcium-containing stones.…”

Inhibition of calcium oxalate nephrotoxicity with Zamzam water

“…Current evidence suggests that the consumption of diets low in calcium is associated with a higher overall risk for the development of kidney stones [7]. This is perhaps related to the role of calcium in binding ingested oxalate in the gastrointestinal tract.…”

“…For the treatment and/or the prevention of calcium oxalate kidney stone formation, different approaches have been tested [7][8][9]. Oxalate metabolism considered to be almost identical between rats and humans, a rat model of calcium oxalate nephrotoxicity can be used to test the effect of different compounds on oxalate nephrotoxicity and which of them can alter the solubility of oxalate [10].…”