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Diet for kidney stones – basic nutritional guidelines
Table of Contents
1. What's a kidney stone?
Kidney stones are a chronic systemic disease that involves the presence of insoluble deposits in the urinary system in the form of stones or salt crystals. They are the result of dissolving chemicals in the urine (when the concentration of compounds exceeds the so-called'soluble threshold' in the body). Stones can form in any part of the urethra, be single or multiple, and settle one or both sides in the kidneys (most commonly the kidney pelvis), saline urine and bladder. They may be composed of calcium (71%), calcium (26%) and phosphorus.2. Reasons behind kidney stones
There are many causes of kidney stones, some of the most common ones include: not enough fluids in the diet or too much of it (e.g. due to weight loss, intensive physical activity in hot conditions), extreme pH of urine (< 5.5 and > 7), which decreases the solubility of some ingredients, high relative density of urine, inadequate diet (too much protein, sodium, high in saliva), deficiency of compounds that restrict the crystallization of phosphorus compounds, obesity and overweight, long-term immobility, frequent and chronic infections of the urinary system, the presence of other diseases such as osteoporosis, uric acid stones, hyperthyroidism, hyperparathyroidism, diabetes, metabolic syndrome, congenital metabolic disorders such as adenine phosphoribosyltransferase deficiency, xanthine oxidase deficiency, orotic aciduria type I, alkaptonuria, and genetic predisposition (M. Grzymisławski 2019; H. Ciborowska, A. Rudnicka 2014).3. Symptoms of kidney stones
The most common symptoms of kidney stones are: severe pain in the lumbar region, known as renal colic, nausea, vomiting, excessive sweating, pale skin, fever, restlessness, frequent urination in small amounts, anuria (in cases where the stones completely block the flow of urine), hematuria, constipation and bloating, urinary retention, pyelonephritis (M. Grzymisławski 2019; H. Ciborowska, A. Rudnicka, 2014).4. Nutritional recommendations for limestone and calcium stones
This type of stones develops when there is excessive consumption of citric acid or acid in the urine, after an operation to remove part of the intestine, in cases of inflammatory bowel disease, excessive intake of vitamin C, insufficient intake of vitamin B6, and impaired excretion of hydrogen ions by the kidneys. In the presence of limestone and calcium stones, it is recommended to limit salt and products with added salt. If the stone is formed as a result of excessive excretion of calcium, for example, in hyperthyroidism or osteoporosis, it is not recommended to reduce calcium intake in the diet. It is also recommended to drink at least 2 liters of fluid per day. Limiting the consumption of animal protein is also important. Increasing the intake of vitamin B6 can help reduce the risk of this type of stones. It is possible to distinguish recommended, allowed in limited quantities, and prohibited products. Prohibited products include: spinach, sorrel, rhubarb, strong teas, coffee, cocoa, dried figs, chocolate, meat preserves, fish preserves, pickles, and soup concentrates. In limited quantities, the consumption of milk and milk products, legumes, potatoes, carrots, beets, peas, tomatoes, green and cabbage vegetables, plums, gooseberries, nuts, and sugar is allowed. However, it is recommended to consume large quantities of fluids, fruit juices, citrus fruits, whole-grain cereal products, cucumbers, onions, and corn.5. Dietary recommendations for phosphate and calcium stones
In this case of stone, the ingredient is calcium phosphate, which is produced in the basic urine often resulting from bacterial infection. Dietary therapy should aim to limit the supply of salt and products rich in phosphorus, calcium and starch (e.g. milk, eggs, starch seed, cottage cheese). The products that are contraindicated in phosphate and calcium stones include: alkaline mineral waters (ph > 7), starch seed, spinach, juice, potatoes, raspberry, mackerel, pepper, starch, cocoa, strong dishes, salt, sauces, salts, M.A. and others. Limited intake of: potatoes, other vegetables, fruits, milk, eggs is allowed. Recommended products include: high fluid intake, meat, fish, bread, coarse-grain cereals, pasta, butter, honey, fruit juices and citrus fruits.6. Nutritional recommendations in the urinary bladder
The cause of this type of kamikaze is a high-purity diet (obesity in meat, fish, mushrooms, etc.), excessive concentration of uric acid in the blood, and pH < 5.3. The compounds are derived from urea acid, which is the final product of metabolism, but is normally dissolved and excreted by the kidneys. The disease that promotes this type is urea, which consists of excessive accumulation of urea in blood and which is deposited in the muscles and joints. The diet should be based on the alkalinization of the urea as the urine dissolves in the alkaline medium of the milk and milk products.7. Nutritional guidelines for phosphate, magnesium, and ammonium stones
The components of phosphorus-magnesium-ammonium stones often result from bacterial infections of the urinary system. Due to the higher prevalence of these infections among women, they are more commonly affected by this type of stones. The diet consists of limiting the intake of phosphates found in maturing cheese, melted cheers, egg yolks, milk and its derivatives, meat products, fish, canned food, coarse-grained cereal products, dried seeds of legumes, cocoa, chocolate, and nuts. As with other types of stones, it is advisable to increase fluid intake. In cases of low citrate and magnesium levels in urine, it is recommended to increase the consumption of citrus fruits and juices, as well as magnesium-rich products such as corn, sunflower seeds, leafy green vegetables, and bananas.8. Dietary recommendations for cystine stones
In the presence of cystine stones, it is crucial to limit the intake of sulphur amino acid, cysteine. Cystine stones occur in approximately 1-2% of cases. These stones can reach significant sizes and fill the calcareous-pelvic system. This type of stones is present in patients with cystinuria, a congenital disorder affecting the re-absorption of amino acids, including cystines, ornithines, arginine, and lysine. Cystine is found in high amounts in dairy products. Dietary therapy for cystine stones involves increasing fluid intake to over 3 liters per day, which is best achieved by doubling the recommended daily intake for the body. It is also recommended to increase the intake of vitamin B6, whose rich sources are yeast, legumes, cooked beef, pork, veal, poultry meat, fish, bell peppers, Brussels sprouts, cabbage, carrot, spinach, potatoes, whole-grain bread, powdered milk, eggs, cow milk, bananas, oranges, and apples.9. Dietary recommendations for xanthine stones
This type of kidney stone is caused by excessive concentrations of insoluble purine principle, xanthine, in the urine. Xanthinuria is a disease caused by a deficiency of xanthine oxidase, which prevents the conversion of xanthine to uric acid. Dietary therapy in this case involves a low-purine diet, limiting the consumption of meat, fish, and mushrooms, as well as a high intake of fluids and products that alkalize the urine. The milk-rice diet is particularly recommended.10. General nutritional advice summary
Regardless of the type of stones and other individual factors, a very important role is played in preventing kidney stones from forming. To minimize the risk of recurrence and formation of kidney stone stones, a sufficient amount of fluid over 2 l/ day should be taken. It is also important to take them before bed, at night (when you wake up) and immediately after waking up.
