Kidney stones are small, hard deposits that form in the kidneys. They develop when there is a decrease in urine or an increase in certain substances, such as minerals and salts. Changes in diet can help prevent them.
In this article, we outline some of the dietary choices a person can make to reduce the risk of developing kidney stones, including foods to eat and avoid.
People who wish to prevent kidney stones developing for the first time or reduce the risk of recurrence if they have already had stones should follow these main steps:
- drink plenty of water
- limit their intake of salt and animal protein
- restrict foods that contain high levels of oxalates
- get enough calcium
There is no single diet plan for all types of kidney stones, as they can form due to a buildup of several different minerals in the body. However, many dietitians and doctors who specialize in kidney diseases, or nephrologists, recommend the Dietary Approaches to Stop Hypertension (DASH) diet for people with kidney stones.
This diet has demonstrated the ability to reduce the risk of kidney stone formation and improve other elements of overall health, such as lower blood pressure and a reduced risk of heart disease, stroke, and cancer.
The DASH diet encourages people to consume vegetables, fruits, whole grains, and low-fat dairy. The plan also suggests limiting the intake of salt, sugar, and red meat.
However, dietary changes mainly affect people at risk of the following types of kidney stone:
- calcium oxalate stones
- calcium phosphate stones
- uric acid stones
- cystine stones
People should speak with their healthcare provider to work out which type of kidney stones they have had, if any, to support effective dietary choices. The National Kidney Foundation recommend cutting back on sodium in the diet rather than reducing calcium intake.
Because kidney stones vary according to the minerals they contain, dietary recommendations will also vary.
A person should talk to their doctor about which foods cause stones to help them determine what they should and should not eat to help avoid the formation of stones in the future.
The following are some suggestions on what to include in a diet to avoid the formation of kidney stones.
Including extra water in the diet can help prevent kidney stones, as they often occur due to dehydration. The National Institute for Diabetes and Digestive and Kidney Diseases (NIDDK) recommend drinking 6–8 glasses every day.
Drinking some other fluids as well as water is acceptable. However, it is important to check sodium levels in the beverage, as many drinks have a high salt content.
It is also best to avoid particularly sugary drinks, such as sweetened juices and sodas.
Calcium and oxalate-rich foods
A person should include foods rich in calcium, especially if they consume many foods that are higher in oxalate, such as spinach. A diet low in calcium increases the risk of developing kidney stones. Calcium and oxalate bind together in the intestines, interrupting the formation of stones.
Some foods to include are:
- low-fat or fat-free milk products
- calcium-fortified foods, such as cereals, bread, and juices
- calcium-rich vegetables, such as broccoli
- seaweed, such as kelp
Fruits and vegetables
Fruits and vegetables are a necessary part of any diet. Increasing the number of vegetables in their diet can help a person prevent stone formation. Fruits can be dried, frozen, or fresh.
People should become familiar with fruits and veg that have high oxalate content, including spinach, and try to limit the amount in the diet. Alternatively, people can combine them with foods that contain high amounts of calcium.
Small amounts of animal-based proteins are safe to consume. However, too much animal protein can increase a person’s risk of kidney stones.
Dietitians encourage the inclusion of plant-based protein sources in a kidney stone diet. Examples include beans, peas, and lentils.
People should discuss their individual protein needs with a doctor or a dietitian, as the requirement will vary from person to person.
Choosing which food to limit depends on the type of stone developing in a person’s body.
Foods to limit, include:
- high-sodium foods, including processed, packaged foods as well as meals from fast food establishments
- certain animal proteins, including eggs, fish, pork, and beef
If a person has had calcium oxalate stones, they may wish to restrict their intake of the following foods, which are high oxalate and may increase the risk of recurrence:
- wheat bran
Every person is different, and individual needs and dietary requirements will vary.
The most important aspect of managing diet when looking to prevent recurrent kidney stones is speaking to a doctor or dietitian. They will be able to identify the type of kidney stone that is developing and ways to slow or stop its development.
Kidney stones form when a person’s urine output decreases, and when the kidney contains large numbers of certain minerals that stick together and form stones.
Common kinds of kidney stones include:
- calcium oxalate stones
- calcium phosphate stone
- struvite stones
- uric acid stones
- cystine stones
A range of factors can cause kidney stones, including the following dietary factors:
- high oxalate intake from certain foods
- a high protein diet
- too much sodium
- dehydration or low fluid intake
High oxalate foods, such as nuts, seeds, beets, spinach, and buckwheat flour, can contribute to calcium oxalate stones, although this does not mean that people need to exclude them from the diet completely.
A high protein diet can contribute to the formation of calcium phosphate stones. A high sodium intake and dehydration can contribute to uric acid and cystine stones.
Some foods contain certain chemicals or compounds that can influence the production of kidney stones, particularly if a person regularly eats them in high amounts.
By limiting the intake of these foods, the risk of kidney stones reduces.
For some people, dietary changes may be enough to prevent kidney stones from occurring.
In other cases, additional treatment may be necessary, including medication to break the stones up or surgery to remove the stones.
If stones become extremely painful, it is best to seek consultation with a doctor or nephrologist so they can recommend the best course of action.