Diet for kidney stones: fundamental principles

The diet prescribed by urologists and nephrologists for kidney stones cannot be the same for everyone who suffers from kidney stone disease. The therapeutic diet must correspond to the chemical composition of the stones formed in the kidneys.

So, what is the diet for kidney stones? And, most importantly, which one is right for you?

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Kidney Stone Treatment with Diet

Although the development of nephrolithiasis ( kidney stone disease ) is caused by a number of reasons, the mechanism of stone formation is triggered by disturbances in the processes of formation and utilization of chemical compounds that are part of urine. Such compounds include: sodium and potassium salts of uric acid (urates), calcium and ammonium salts of oxalic acid (oxalates), calcium salts of phosphoric acid (phosphates) and calcium salts of carbonic acid (carbonates).

The fundamental principles on which the treatment of kidney stones with diet is based are to limit the intake of those substances with food whose metabolism deviates from the norm. Or, as an option, it is recommended to introduce into the usual diet products that contain substances that help neutralize stone-forming factors.

For example, when purine metabolism is disrupted, urate stones are deposited in the kidneys, since uric acid is the end product of purine base metabolism. Humans do not have the enzyme uricase, which breaks down uric acid salts, so excess purines lead to an increase in the content (more than 70 mg/l) of uric acid either in the blood (hyperuricemia) or in the urine (uric acid diathesis or hyperuricuria). Uric acid, which is poorly soluble in water, in the form of sodium urate crystals, is deposited in the joints (with the well-known gout), and with high urine acidity (pH < 5-5.5), it crystallizes in the renal pelvis or urinary bladder.

In addition, a diet for kidney stones should take into account that the formation of stones is determined by the acidity level of urine. Thus, oxalate stones are formed in slightly acidic urine (pH = 5.8-6.5), and alkaline urine (pH> 7-7.5) is a favorable environment exclusively for the crystallization of phosphoric acid salts. On this basis, food products are recommended that can either alkalize urine or increase its acidity.

General recommendations for all types of kidney stones boil down to increasing the volume of fluid consumed: you should drink at least two liters, half of which should be water. This is necessary to ensure the therapeutically necessary level of daily diuresis for nephrolithiasis. And it is imperative to reduce the amount of salt - so that fluid is not retained in the body.

The condition of the urinary tract mucosa depends on the content of retinol (vitamin A), so its deficiency in the body should not be allowed. But ascorbic acid (vitamin C) and calciferol (vitamin D) require caution. Ascorbic acid (if consumed in excess) increases the acidity of urine, and vitamin D activates the reabsorption (reverse absorption) of calcium in the intestine and phosphorus in the kidneys. Although the relationship between these vitamins and the occurrence of nephrolithiasis is not recognized by all specialists.

Diet for oxalate kidney stones - oxaluria

The diet for oxalate kidney stones requires completely eliminating foods that contain a lot of oxalic acid or oxalates: potatoes, eggplants, tomatoes, carrots, zucchini, green leafy vegetables (spinach, sorrel, parsley, celery), green and hot peppers, garlic, beans and soy products, as well as all kinds of nuts.

What should you not eat if you have kidney stones caused by oxaluria? Specialists from the National Cancer Institute (American National Cancer Institute) strongly advise not to rely on buckwheat, millet, maize (corn porridge) and rye bread; to minimize the addition of spices such as black pepper, ground ginger, coriander, curry, cloves, cinnamon, anise seeds to dishes.

The "black list" of oxalate-containing fruits and berries includes: apples and pears; oranges and tangerines; kiwi, persimmon and pineapple; apricots and peaches; dark plums and prunes; raspberries, strawberries, red currants, gooseberries, dark grapes.

Cocoa (and, naturally, chocolate), coffee (including instant coffee), beer, black tea, rosehip infusion, and juices – orange, grape, carrot, tomato – contain a lot of oxalates.

What can you eat with kidney stones? With oxalate stones, the diet may include: meat and bacon; poultry; fish (except sardines) and seafood; eggs; milk and cheese; pasta, wheat bread, rice, oatmeal, mushrooms, sugar, honey. The list of permitted products includes cabbage (white cabbage, cauliflower, kohlrabi); cucumbers and green peas; radishes and red peppers; watermelons, melons and pumpkin; bananas and avocados; green grapes; apples (without skin) and apple juice. And, of course, green tea.

Doctors prescribe pyridoxine (vitamin B6) to patients with oxaluria. In addition, yeast (baker's or brewer's), fish, beef and beef liver, chicken and egg yolks will help replenish the supply of this vitamin.

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Diet for urate kidney stones - uraturia

Since the formation of urate stones from uric acid salts is facilitated by an increased hydrogen index (pH) of urine, reducing its acidity (alkalization) is the basis of the diet for urate kidney stones.

The following are best suited for this: cabbage, cucumbers, tomatoes, radishes, peppers, beets, carrots, celery, apricots (fresh and dried), peaches, apples, cherries, currants, gooseberries, grapes, prunes, figs, watermelon, melon. The level of urine acidity can be balanced by eating oatmeal, boiled potatoes, citrus juice (orange, lemon), milk (only fresh raw).

It is very important to know what you can't eat with kidney stones in uraturia. Since the increase in uric acid content is provoked by acidic metabolites of the breakdown of animal proteins (in particular, sulfur-containing amino acids and urea), the diet should be mainly plant-based and dairy. So you will have to give up meat (especially red), meat broths, offal, sausage and canned food. Although nutritionists have an alternative for those who are unable to cope with such a restriction: strictly "dose" meat consumption and cook it according to the rules that will reduce the amount of toxins.

Firstly, the daily portion of meat should be determined based on the calculation - one gram for each kilogram of body weight. Secondly, the meat should not be stewed, fried or even baked, but boiled. Moreover, drain the water after the first boiling, fill it with water again and add a whole onion and a small carrot (which are thrown away after cooking).

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Diet for phosphate kidney stones - phosphaturia

Considering that crystallization of calcium salts of phosphoric acid occurs with an excess of calcium and phosphorus against the background of alkaline urine, it becomes obvious what kind of diet for kidney stones is necessary in this case.

To reduce the intake of these macronutrients, nutritionists at the US National Kidney Foundation (NKF) recommend not to consume: milk and fermented milk products (primarily cottage cheese and cheeses), sea fish and seafood, buckwheat, pearl barley, oatmeal, eggs, legumes, grapes and garlic, eggplants and cucumbers, lettuce and pumpkin. Beets, sorrel, spinach, and chocolate interfere with the absorption of calcium.

A diet for phosphate kidney stones should simultaneously ensure a change in urine reaction from alkaline to acidic, for which you should include in your menu: meat, lard, offal, fats and oils, legumes, cereals, corn, rice, nuts and seeds (walnuts, sesame, peanuts, sunflower), sugar-containing products, tea, coffee, various spicy seasonings. Fried foods are also not prohibited.

Domestic nutritionists prescribe their patients with phosphaturia diet 14, used for urolithiasis, with a full diet and limited alkalizing products. And the list of recommended (except for those mentioned above) includes fish, absolutely all cereals, mushrooms, pumpkin, green peas, sour apples and berries.

Diet 7 for kidney stones, recommended by some doctors, is intended for patients with chronic nephritis (inflammation of the kidneys) or for the recovery period in the acute form of this pathology. This diet limits salt intake (no more than 7 grams per day) and is aimed at "moderate sparing of kidney function, impact on high blood pressure and edema."

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Diet for calcium kidney stones - hypercalciuria

Filtration of calcium cations (Ca ²⁺ ) is carried out by the kidneys, and in the case of an increase in the content of this macroelement in the blood, its concentration in the urine also increases.

A diet for calcium kidney stones involves a maximum reduction in the consumption of calcium-rich foods, and this is, first of all, milk and all milk-based products. In addition, it is recommended to limit meat consumption, since animal protein increases the level of calcium in the urine. But the fact is that both oxalates and phosphates (as indicated at the beginning of the section) are calcium stones. So calcium is present in almost all types of kidney stones, and therefore, among professionals in therapeutic dietetics, the term "diet for calcium kidney stones" is not in use. And the appointment of a diet for nephrolithiasis is carried out taking into account the content of Ca in the stones, but the fundamental principle is what acids it reacted with. And since calcium and phosphorus participate in most biochemical processes in the body in the form of calcium phosphate, the same diet can be recommended for calcium stones as for phosphaturia (especially since calcium is found in most foods in the form of calcium phosphate).

NKF experts claim that for the purpose of prevention, regulating the amount of calcium in the diet can prevent hypercalciuria only in rare cases, since the body does not absorb more calcium than necessary. According to most foreign doctors, calcium contained in food does not affect the risk of kidney stones. After all, stones are formed when calcium binds with acids, in the case of oxaluria - with oxalic, which is one of the strongest organic acids of the carbon group. It easily binds cations of metals such as iron and magnesium, not to mention calcium, which is an alkaline earth metal.

By the way, if you are interested in a diet for coral kidney stones, you need to clarify: there is no such diet. Coral, or more precisely coral-like, are stones of various chemical compositions that have a branched shape similar to colonies of sea polyps. And the shape of the stones - as unnecessary - is not taken into account by the therapeutic diet.

In order for kidney stones not to darken your life, you need to be responsible about what is included in your daily diet. And a strict diet for kidney stones will greatly ease the course of the disease.

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