Kidney stones are hard masses that form from crystals in the urine. Sometimes, they do not have recognizable symptoms, but often, kidney stones can be very painful. Either way, you will want to avoid them, or maybe you’ve had them and you’re in no rush for them to return. There are preventative actions you can take with changes to your diet plan that will help keep kidney stones from building.
Before we begin with diet recommendations, it’s important to note that all kidney stones are not the same. The most common type of kidney stone is a calcium stone, with uric acid stones following close after. Diet and medical treatment are different depending on the stone type.
The National Kidney Foundation gives these diet recommendations dependent on the kidney stone type.
1. Calcium Oxalate Stones: most common stones
Oxalate is naturally found in many foods, including fruits and vegetables, nuts and seeds, grains, legumes, and even chocolate and tea. Some examples of foods that have high levels of oxalate include peanuts, rhubarb, spinach, beets, Swiss chard, chocolate and sweet potatoes. Limiting intake of these foods may be beneficial for people who form calcium oxalate stones which is the leading type of kidney stone.
Eat and drink calcium foods such as milk, yogurt, and some cheese and oxalate-rich foods together during a meal. The oxalate and calcium from the foods are more likely to bind to one another in the stomach and intestines before entering the kidneys. This will make it less likely that kidney stones will form.
Calcium is not the enemy but it tends to get a bad rap! This is most likely due to its name and misunderstanding that calcium is the main cause in calcium-oxalate stones. A diet low in calcium actually increases your chances of developing kidney stones.
Don’t reduce the calcium in your diet. Work to cut back on the sodium in your diet and to pair calcium-rich foods with oxalate-rich foods. The recommended calcium intake to prevent calcium stones is 1000-1200 mg per day (you can eat 3 servings of dairy products with meals to meet the recommendation).
Extra sodium causes you to lose more calcium in your urine. Sodium and calcium share the same transport in the kidney so if you eat high sodium foods it will increase calcium leakage in the urine. Therefore, a high sodium diet can increase your chances for developing another stone. There are many sources of “hidden” sodium such as canned or commercially processed foods as well as restaurant-prepared and fast foods.
You can lower your sodium intake by choosing fresh low sodium foods which can help to lower calcium leakage in the urine and will also help with blood pressure control if you have high blood pressure.
2. Uric acid stones: another common stone
Red meat, organ meats, and shellfish have high amounts of a natural chemical compound known as purines. High purine intake leads to a higher production of uric acid and a larger acid load for the kidneys to excrete. Higher uric acid excretion leads to more acidic urine. The high acid concentration of the urine makes it easier for uric acid stones to form.
To prevent uric acid stones, cut down on high-purine foods such as red meat, organ meats, beer/alcoholic beverages, meat-based gravies, sardines, anchovies and shellfish. Follow a healthy diet plan that has mostly vegetables and fruits, whole grains, and low-fat dairy products. Limit sugar-sweetened foods and drinks, especially those that have high fructose corn syrup. Limit alcohol because it can increase uric acid levels in the blood and avoid short term diets for the same reason. Decreasing animal-based protein and eating more fruits and vegetables will help decrease urine acidity and this may help reduce the chance for uric acid stone formation.
General Diet Recommendations for Kidney Stones:
Drink plenty of fluid: 2-3 quarts/day
This includes any type of fluid such as water, coffee and lemonade which have been shown to have a beneficial effect with the exception of grapefruit juice and soda. This will help produce less concentrated urine and ensure a good urine volume of at least 2.5L/day.
Limit foods with high oxalate content
Spinach, many berries, chocolate, wheat bran, nuts, beets, tea and rhubarb should be eliminated from your diet intake.
Eat enough dietary calcium
Three servings of dairy per day will help lower the risk of calcium stone formation. Eat with meals.
Avoid extra calcium supplements
Calcium supplements should be individualized by your physician and registered kidney dietitian.
Eat a moderate amount of protein
High protein intakes will cause the kidneys to excrete more calcium therefore this may cause more stones to form in the kidney.
Avoid high salt intake
High sodium intake increases calcium in the urine which increases the chances of developing stones. Low salt diet is also important to control blood pressure.
Avoid high doses of vitamin C supplements
It is recommend to take 60mg/day of vitamin C based on the US Dietary Reference Intake Excess. Amounts of 1000mg/day or more may produce more oxalate in the body.
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