I have multiple kidney stones. I would like to know what kind of foods I should avoid. What kind of natural treatment, if any, do you recommend? My doctor told me to drink plenty of water and to avoid tea. I know there must be more food/drink that I should avoid than just that.
Knowing the mineral content of the kidney stone guides the treatment strategy. The majority of kidney stones contain calcium in combination with oxalate, phosphate, or carbonate. Other stones contain uric acid, struvite, or cystine. As calcium oxalate is the most common stone, reducing foods containing oxalates seems an obvious treatment strategy. But, there is controversy surrounding eliminating oxalate-containing foods such as beans, spinach, kale, blackberries, strawberries, soy, nuts, and tea, as theseare considered “healthy” foods. Calcium binds oxalate in the digestive tract and prevents absorption of both compounds. So, it seems, eating higher calcium foods with higher oxalate foods may be a better strategy than simply avoiding high oxalate foods.
Preventing calcium precipitation in the urine (called hypercalciuria) appears to be the best treatment strategy. Common sense suggests hypercalciuria results from increased calcium consumption. But, as calcium is tightly regulated in the body, this precipitation reflects a metabolic dysfunction rather thans imply excessive calcium intake. These metabolic factors are sodium, potassium, and dietary protein.
Sodium and potassium are essential electrolytes that play an important role in cellular function. As such, the ratio of sodium to potassium is an important consideration. For example, ancestral diets contained on average 16X potassium compared to sodium, whereas modern diets contain 4X sodium compared to potassium. Research suggests sodium increases the precipitation of calcium in the urine, whereas potassium decreases it. Dietary protein, especially acid-forming animal protein, adds further metabolic burden on the body. An acidic diet increases the risk of kidney stone formation, as it forces the body to consume potassium as a metabolic buffer instead of balancing sodium intake. Whether from a relative deficiency (increased sodium intake) or from depletion (acidic diet), potassium deficiency plays a major role in calcium precipitation. This is also important in the development of osteoporosis.
In other words, the unbalanced standard American diet represents an underlying cause of kidney stone formation. These dietary habits help prevent hypercalciuria:
- Eat more vegetables and fruits to increase potassium.
- Decrease animal protein intake to prevent metabolic acidity.
- Decrease processed foods intake to limit sodium (75 percent of sodium on average comes from processed foods whereas only 25 percent comes from the salt shaker).
Eating more vegetables and fruit can have a trickledown effect by reducing intake of animal protein and processed foods. This is the zero sum relationship, which suggests eating more of one food means eating less of another if calories remain constant.
Increasing fluid intake appears modestly effective. The goal is to produce 2-3 liters of urine every day. Unfortunately, this effect is diminished with increased sodium intake and it will not be enough to treat those with hypercalciuria.
Various vitamins have been associated with kidney stone formation. Vitamin C can be converted to uric acid in the body and, thus, has been considered in important factor in uric-acid-containing kidney stones. But this hypothesis is not supported by research, which suggests vitamin C is considered safe at high doses. Uric acid stones are best addressed by decreasing sugar (fructose) intake and limiting high purine meats, such as organ meats and sardines.
Vitamin D has caused concerns, as a study suggested a combination of calcium and vitamin D increased kidney stone formation. In research studies it is impossible to control for all dietary factors that may influence the outcome. As this study did not control for sodium, potassium, or animal protein intake, conclusions based upon modest levels of calcium and vitamin D should be taken with a grain of salt (and much more potassium).