5 Nutrition Tips for Preventing Kidney Stones

Written by: Emily Russo, MS, RD, CDN

If you’ve ever had a kidney stone – or know someone who has – check out these nutritional tips to help stay stone-free this year!

If you’ve ever had a kidney stone – or know someone who has – check out these nutritional tips to help stay stone-free this year!

Most of us know someone who has had a kidney stone. In fact, 1 in 10 people will have one in their lifetime with accompanying pain often compared to childbirth – ouch!

For those who have had kidney stones or are at high risk for developing them, lifestyle modifications are usually the first line of defense. So, below are five nutrition practices that can give your kidney a better shot at staying stone-free!

But first a few quick basics on kidney stones…

  • A kidney stone is formed from minerals and salts in the urine that crystallize and stick together. A stone can be so small it’s hard to see, or in rare cases as large as a golf ball! The pain results when the stone tries to pass through the small passage of the urinary tract.
  • Once a stone is passed, it/they should be collected to determine which type of kidney stone it is. Typically, patients are given a special container to catch them on the way out.
  • There are four types of kidney stones – the most common is calcium-oxalate (80% of all stones), followed by uric acid, and less commonly struvite (from infection), and cystine. Each stone will have its own variation of treatment plans, so that’s why it’s important to identify the type.
  • Those who have had a stone previously are more likely to have another one. Others at higher risk for developing stones include those with a family history, who take certain medications, or who have other medical conditions. Lifestyle factors, such as low fluid intake (more on that below), also play a role.
Of note, most research studies on kidney stone intervention are done on those at high risk for stone development or recurrence, and so this advice is most applicable to that population.

If there’s one takeaway here, this is the most important.

Drink fluid and stay hydrated. Fluid dilutes the urine and offers protection against stones, which are more likely to form in concentrated urine.

How much fluid do we need to drink?
This will vary for individuals and depends on the season. There is not one prescribed level. Meeting fluid needs is often most challenging at the beginning of summer when we start to sweat, and telltale signs we need to drink more (beyond feeling thirsty) include dry skin and mouth, dark yellow urine, decreased urine output, and reduced frequency of urination.

Does it matter which kind of fluids we drink?
Water is a great choice, but for some that can get monotonous. Flavor water with fresh fruit, cucumber slices, or a splash of lemonade to mix things up. Fresh fruit or ice pops also have high percentage water and are good ways to maintain hydration.

For those who need to manage blood sugar, fruit juice is higher in carbohydrate and not a great choice to drink in large volumes. And while cranberry juice in particular is often regarded as a good way to maintain kidney health, it will not prevent recurrence of kidney stones.

Additionally, some studies show that drinking soda may have an impact on kidney stone recurrence. The mechanism of this is unclear because there are a few variables to consider. In theory, it could be related to the phosphorus (although that’s only found in darker sodas) or the fructose (but that wouldn’t be the case for artificial sweeteners) because these may increase the urinary excretion of stone-forming minerals.

Some studies show coffee and tea are associated with decreased recurrence of kidney stone formation. This could be due to a diuretic effect or because of the phytochemicals present. It is unclear because results have been shown with caffeinated and decaffeinated varieties, but there are no direct conclusions.

For those who drink alcohol, some studies show an association between beer and wine drinkers and a decreased incidence of stone recurrence. The association could be related to increased fluid intake, increased output, or something else all together.

Some physicians will prescribe potassium citrate, or citrate in some form, for those at risk for stones. The idea is that this can increase urine citrate (which can prevent calcium stones) and increase pH levels for uric or cysteine stones. But, this will depend on the individual’s history, type of stone, and tolerance to the medication – it can cause stomach upset.

Instead, drinking straight lemon juice, also referred to as unsweetened lemonade, has become a popular practice to up citrate intake and can also help meet fluid needs. Some studies show drinking the juice of about four lemons daily may have a similar effect, but it’s not guaranteed. It’s worth noting that lemon juice can also cause tooth enamel erosion and stomach discomfort, especially when ulcers are present, so this is not a perfect plan either.

We are already tuned in to eating fruits and vegetables for overall health, so this is likely consistent with our everyday planning. Consider mixing in a variety of citrus fruits, which as noted above, may raise urine citrate levels.

For those with calcium-oxalate stones, oxalate-heavy fruits and vegetables may need to be monitored more closely. Because oxalates are a bit niche, not many of us can rattle of a high-oxalate food list. But some examples include beets, rhubarb, and Swiss chard.

Noted in detail below, these foods do not need to be avoided, simply accounted for.

A moderate dietary salt restriction is useful in limiting urinary calcium excretion, which may be helpful in preventing stone recurrence. Those with higher blood pressure, kidney, or heart disease may already be moderating dietary sodium intake.

This doesn’t mean salt needs to be avoided completely and will depend on the individual’s needs. But a good first step to keep from overdoing it on sodium is to be cautious with the saltshaker after food is prepared. A mere one teaspoon of table salt is about 2300mg of sodium and is more than most of us need in a whole day!

Sodium in packaged foods can be more easily monitored using the nutrition labels, just remember to calculate total sodium per serving. Meaning, if the serving size is 5 crackers, for example, and someone eats 10, the amount of sodium listed on the nutrition label needs to be doubled.

One of the biggest misconceptions about kidney stones is that you have to completely avoid certain food groups. For example, because the most common kidney stone is calcium-oxalate, we may assume that avoiding all calcium and oxalate foods is the way to go. But calcium is vital to our health and oxalates are found in many nutritious produce, so this is not appropriate.

The recommendation is actually to meet standard calcium requirements, because calcium actually helps to bind oxalate in the gut before the kidneys begin processing. This makes it less likely that kidney stones will form. Perhaps counterintuitively, a diet low in calcium increases the risk of developing kidney stones. If concerned about foods with high calcium or oxalates, the best bet is to pair calcium-rich foods with oxalate-rich foods in the same meal.

Only those with uric acid stones (a smaller subset) may be advised to reduce intake of high purine foods, which can lead to higher production of uric acid, potentially spurring on recurrence. This is similar to dietary guidelines for another condition called gout. A few main examples of high purine foods include meat, shellfish, and alcohol.

There are four different types of kidney stones and a multitude of reasons why they may develop or recur. Physicians will make an individualized plan based on a person’s full medical history and any comorbidities.

Because of this, it could be counterproductive, even dangerous, to take generic advice from friends and other sources, or to take vitamin supplements or “kidney health” drinks and powders until speaking with your doctor.

Kidney stones are complicated and require individual attention. Treat them as such by limiting generic advice from friends or through media channels.

Adequate fluid intake is most important in preventing recurrence of kidney stones and is especially vital as the weather gets warmer.

🧡 As always, please share any questions or comments about kidney stones below. We love hearing from readers!

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