You may have heard that there are particular foods that cause kidney stones. Whilst this is not technically correct (the foods themselves do not cause the stones to form), certainly limiting these foods can help to prevent kidney stones from forming.
You may have heard that there are particular foods that cause kidney stones. Whilst this is not technically correct (the foods themselves do not cause the stones to form), certainly limiting these foods can help to prevent kidney stones from forming.
Kidney stones can form when certain chemicals that are found in the urine become highly concentrated; enough so that they come together to form crystals, which can then become stuck along the urinary tract. Kidney stones can cause excruciating pain if they block the flow of urine.
Are there foods that cause kidney stones to form?
In terms of foods that cause kidney stones, or rather, that can contribute to the formation of kidney stones, most kidney stones occur when calcium combines with oxalate. They can also form from excessive uric acid in the urine. These two types of stones can be influenced by dietary choices. Other types of kidney stones (including cystine and struvite stones) are not typically related to foods.
When there is too much calcium, oxalate or uric acid in the urine, crystals form, which condense to form kidney stones. It could also be that the urine doesn’t contain enough of the substances that prevent the crystals from sticking together. These two factors can then create an ideal environment for kidney stones to form.
Once you have had kidney stones once, your chances of developing another stone is around 5-10% each year, with some people experiencing recurring stones throughout their lives.
What are the types of foods that cause kidney stones, or contribute to their formation?
If you have had kidney stones in the past, your doctor may recommend that you avoid or limit foods that cause kidney stones to form, or contribute to their formation.
If you have had calcium-oxalate stones, your doctor might advise that you limit foods that contain high levels of oxalate, such as:
- Beets
- Spinach
- Rhubarb
- Nuts (almonds and cashews particularly)
- Chocolate
- Black tea
Oxalates are found naturally in many plants, as well as being produced by the liver, so it is not possible to avoid them all together. Trying to limit high-oxalate foods can help.
Consuming too much animal proteins (such as meats, poultry, eggs and seafood) can increase the level of uric acid in the bloodstream, which may lead to the formation of kidney stones. Animal proteins are also considered to be foods that cause kidney stones (or contribute to their formation), since high protein diets tend to be associated with lower levels of urinary citrate. Citrate is a chemical in the urine that helps to prevent stones from forming. Hence lower levels of urinary citrate can lead to an increased risk of kidney stones.
Sodium and how it relates to foods that cause kidney stones
Consuming a high sodium (salt) diet can trigger the formation of kidney stones because it increases the amount of urinary calcium. Reducing the amount of salt in your diet is also beneficial for the health of your heart and blood pressure. Foods that commonly contain high levels of sodium include:
- Canned foods
- Processed or packaged meats
- Fast foods
- Condiments
Milk is not amongst the foods that cause kidney stones
On the contrary, consuming a moderate amount of calcium may help to prevent kidney stones. Dietary calcium binds to oxalates within the intestine, therefore decreasing the amount of oxalate that makes it into the bloodstream and then eventually into the urine. This means that there is less oxalate free to bind with urinary calcium, leading to a decreased risk of kidney stones. It is important to have calcium in your diet otherwise you may develop other health problems including osteoporosis (weak bones).
Limit foods that cause kidney stones and drink plenty of water
Drinking plenty of water is vital to the overall health of your urinary system and is an important part of preventing kidney stones. Drinking extra water helps to dilute the chemicals in the urine that clump together to form kidney stones. Limiting the foods that cause kidney stones and making sure to drink plenty of water may help to prevent formation or recurrence of kidney stones in the future.
Written by Dr. Shekib Shahbaz and Dr. Tony de Sousa