Urolithiasis is considered a common disease affecting more than a million people each year in India. It is also known by other names such as urolithiasis, nephrolithiasis, urinary stones, etc. Epidemiological studies have disclosed the major role ‘diet’ can play in formation and frequency of formation of kidney stones.
Malnutrition and obesity, both increase the risk of kidney stone formation. The increase in kidney stone disease with malnutrition is associated with ammonium urate stones in the bladder, whereas obesity predisposes to calcium-containing stones localized in the upper urinary tract. In obesity, insulin resistance has been associated with an increase in urinary calcium and decrease in renal tubular acid excretion. Impaired renal tubular acid excretion lowers urinary citrate level and enhances the risk of stone precipitation.
Reports show significant correlation between higher dietary animal protein and increase in stone incidence. Protein consumption of children in Europe and North America is three to five times higher than the recommended intake. The increase in dietary protein has been associated with an increase in calcium oxalate stones and higher localization of stones in the kidneys. Diet low in animal protein but high in cereal, shifts the spectrum towards a higher predominance of bladder stones composed of ammonium and urate ions, more commonly seen with malnutrition.
Dietary sodium increases the risk of urolithiasis. Salt intake expands intravascular volume, which can increase urinary calcium level, likely by decreasing renal tubular calcium reabsorption. Increase in salt intake can induce mild systemic metabolic acidosis, which can lower urinary citrate levels, and increases the risk of calcium precipitation in kidneys.
On the contrary, potassium-rich foods lower stone formation through a decrease in urinary calcium excretion. High urinary potassium is believed to increase renal tubular phosphate absorption and consequently inhibit 1,25-dihydroxyvitamin synthesis. Decrease in 1,25-dihydroxyvitamin slows intestinal calcium absorption. Potassium-rich foods offer the additional advantage of high citrate content, thus decreasing the precipitation of urinary calcium.
In cases of Calcium oxalate stones, it is recommended to reduce oxalate and avoid foods like nuts and nut products, peanuts, rhubarb, spinach, wheat bran, etc., to help reduce the amount of oxalate in your urine. It is also advised to reduce sodium intake in diet. Chances of developing kidney stone increases when you eat more sodium. Sodium is a part of salt and it is present in many canned, packaged, and fast foods. It is also in many condiments, seasonings, and meats. Another restriction advised is to limit animal protein. Eating animal protein may increase chances of developing kidney stones. Avoid beef, chicken, and pork, especially organ meats, eggs, fish and shellfish, milk, cheese, and other dairy products.
Although you may need to limit how much animal protein you eat each day, you still need to make sure you get enough protein. Consider replacing some of the meat and animal protein you would typically eat with beans, dried peas, and lentils, which are plant-based foods that are high in protein and low in oxalate. Talk with a healthcare professional about how much total protein you should eat and how much should come from animal or plant-based foods.
