Analysis of Urine Composition Saturation and Dietary Intervention in Subjects Without Urinary Calculi

Urinary calculi have become a global public health problem, which brings a huge economic burden to society and individuals. The pathogenesis of urinary calculi is not completely clear. Supersaturation of urinary components is a necessary condition for the formation of urinary calculi. The causes of stone formation are closely related to diet, drugs, metabolic disorders, basic diseases, genetic factors, environment and so on. Diet essentially determines the composition of urine, which affects the formation of urinary calculi. The effect of dietary phosphorus intake on stones is not clear. There is a lack of data to support dietary phosphorus as an influencing factor of stone formation. Phosphorus is present in most foods. 24h urine composition analysis is of great value in predicting the occurrence and composition of urinary calculi. However, due to the interaction between urine components, a single urine component can not well predict the occurrence of stones. Therefore, the researchers introduced the relative supersaturation of common stone components in urine to predict the incidence of stones. Therefore, we want to give healthy adults a diet with different phosphorus content for a period of time to clarify the effect of phosphorus in the diet on 24h urine composition level and urine relative supersaturation, so as to further explore the relationship between dietary phosphorus and the incidence of urinary calculi. To provide more clear recommendations for early prevention of urinary calculi, and provide more evidence for clinical decision-making, thereby reducing the incidence rate of urinary calculi.

\*Diet: Ordinary phosphorus diet: phosphorus content 1500mg High-phosphorus diet: Phosphorus content is 2500mg (inorganic phosphorus is added to the ordinary phosphorus diet) Low-phosphorus diet: Phosphorus content 500mg (The protein content and the ratio of plant protein and animal protein are consistent with the other two diets by adding egg protein and adding low-phosphorus whey protein powder. In addition, calcium magnesium tablets and potassium chloride salt are added to achieve the same calcium, magnesium and potassium content as others. The two diets are consistent)

There are 2 recipes for each diet, and each recipe guarantees that the energy, protein, fat, carbohydrate, calcium, magnesium, sodium, potassium, oxalic acid content, vegetable protein and animal protein ratio are basically the same:

Energy: 2100kcal (30kcal/kg, standard weight 70kg);Protein: 110g;Fat: 55-60g;Carbohydrate: 300g;Calcium: 600-700mg;Magnesium: 350-400mg;Sodium: 4600mg;Potassium: 2500mg Water:Giving subjects 2L of purified water without any minerals every day

* Specimen We will collect 24h urine and feces for the whole day on the 2nd, 5th, 7th, and 10th days of the experiment, and collected morning blood and random urine on the 3rd, 6th, 8th, and 11th days.
* Analysis We will use Equil 2 software to calculate the relative supersaturation of urine, and use SPSS software to analysis data

Eligibility Criteria:
Inclusion Criteria:

* Age: 20-45 years old
* 18. 5≤Body Mass Index≤ 23. 9
* Normal oral diet

Exclusion Criteria:

* People who have had or are suffering from urinary tract stones , or have the following diseases leading to the formation of stones: renal tubular acidosis, gout, hyperuricemia, chronic diarrhea, insulin resistance, hyperparathyroidism, idiopathic hypercalcemia, hypertension, diabetes mellitus
* CKD-EPI-eGFR\<90ml/min1.73m-2)
* The following drugs are being used: cathartic, aspirin, angiotensin converting enzyme inhibitor，angiotensin II receptor antagonist，diuretic, acid inhibitor, alkali or carbonic anhydrase inhibitor, phosphorus binder, calcium agent and active vitamin D;
* Previous gastrointestinal diseases or gastrointestinal surgery
* Application of enteral and parenteral nutrition
* Complicated with infection, with or without antibiotic treatment
* Mental patients or unable to cooperate for various reasons