The occurrence of kidney stones has been on the rise over the past ten years, it's estimated that one in eleven people will suffer from kidney stones in their lifetime, with 50% of them experiencing a recurrence.
There are many different forms of kidney stones, but calcium oxalate stones are by far the most common, accounting for nearly 70-80% of all kidney stones.
Oxalates, also known as oxalic acid, are naturally occurring compounds in plant-based foods such as vegetables, nuts, legumes, grains, and fruits. They can also be produced by our bodies as a byproduct of metabolism.
Usually, oxalates have no effect on the body and are excreted in the urine. However, In certain people, oxalates in the urine can combine with calcium to form crystals, which can ultimately develop into kidney stones.
In this regard, the greater the amount of oxalate excreted in the urine, the higher the risk of kidney stone formation.(1)
Quick Facts
# Stone formers are believed to be born with a 50% higher rate of intestinal absorption of oxalates than non-stone formers.
# Vegetarians are less likely to develop kidney stones than meat eaters.(2)
# Cutting back on animal protein can help reduce the risk of kidney stones by half.
# Spinach accounts for 40% of oxalate intake in the United States.(3)
# Oxalate in water or juice is easier to absorb than oxalate in solid food.
# Men and older women who consumed spinach eight or more times a month had approximately a 30% higher risk of developing kidney stones.
Symptoms of Hyperoxaluria
Hyperoxaluria occurs when there is an excessive amount of oxalate in the urine. This condition can be caused by various factors, one of which is the consumption of high-oxalate foods.
While most individuals tolerate oxalates well, some people, particularly those with a history of kidney stones (stone formers) may experience specific symptoms if they routinely eat high-oxalate foods such as spinach and almonds.
Excessive oxalate levels can induce pain and inflammation in different parts of the body, especially in the joints. In addition, it can cause burning sensations, eye and skin irritation, and contribute to the formation of oxalate calcium kidney stones.
Symptoms of kidney stones
Symptoms of kidney stones can include:
- Severe or sudden pain on either side of the lower back, below the ribs
- Pain that radiates to the lower abdomen and groin
- Pain that comes in waves and fluctuates in the intensity
- Nausea/vomiting
- Sweating/agitation
- Urine that smells bad or looks cloudy
- Blood in the urine
- Frequent urge to urinate
- Painful urination
- Chills/fever
Keep in mind that these symptoms may not occur until the stones start moving down the ureters.
Kidney Stone Diet
A high oxalate diet, excessive intake of vitamin C, long-term use of antibiotics, obesity, fat malabsorption, and bariatric surgery, are among the factors that increase the risk of developing kidney stones.
If you have a history of kidney stones or are prone to them, there are a few precautions you should take to prevent kidney stones from forming.
A kidney stone diet includes several dietary guidelines, which we will discuss in detail in the ongoing paragraph.
1. Drink more water
Kidney stones form when the fluids in your body become oversaturated, and the optimum way to prevent this supersaturation is by maintaining proper hydration through daily water intake. Drinking plenty of water helps prevent the formation of kidney stones.
You should strive for at least 2.5 liters of fluid each day. Water is always recommended, but you can also increase your fluid intake with natural juices, coffee, tea, fruits and vegetables, and so on.
In addition to preventing kidney stones, keeping your body hydrated has countless other health benefits, including enhanced cognitive function, digestive and heart health, regulating body temperature, and combatting infections.
2. Limit foods high in oxalates
To prevent the formation of oxalate calcium stones, cutting down oxalate-rich foods seems like a good start.
A typical diet provides 200-300 mg of oxalates. However, for individuals prone to kidney stones, most healthcare experts recommend restricting their intake to below 100 mg, with an optimal intake being less than 50 mg.
Foods high in oxalates include spinach, black tea, almonds, chocolate, sweetened sodas, sweet potatoes, soybeans, tofu, cranberry juice, sesame seeds, and rhubarb.
3. Combine calcium with oxalate-rich meals
It may seem logical to believe that consuming more calcium will cause more calcium oxalate stones to form, but this is not the case. In fact, when calcium-rich foods, such as dairy, are consumed at the same time as high-oxalate foods, the calcium binds with oxalate in the digestive system, allowing less oxalates to be absorbed into the blood and end up in the kidney, that is why some cultures add cheese when cooking spinach.(4)
If you're a stone former, eating more calcium-rich foods helps reduce the chance of developing kidney stones, however, if the dietary calcium cannot be increased, we recommend taking 200-400 mg of calcium citrate alongside an oxalate-rich meal rather than separately.
4. Include citrates in your diet
Urinary citrates are a significant factor in the development of oxalate calcium stones, indeed, most people who are susceptible to kidney stones are citrates deficient, they also have higher organic acid levels and lower urinary PH.(5)
Citrates help to raise urinary PH, the higher the dietary acidity load, the greater the risk of developing kidney stones, which is why diets high in animal protein are associated with an increased risk of stone formation.(5)
Additionally, citrates can also combine with calcium in the urine and prevent it from binding with oxalates, which helps to avoid the formation of calcium oxalate stones.
Furthermore, it is believed that citric acid can dissolve small kidney stones by forming soluble citrate salts, which then bind to calcium and help pass kidney stones. Citric acid is naturally present in fruits and vegetables.
To increase citrate levels naturally, you can try incorporating a cup of lemon juice into your diet or consuming fruits and vegetables rich in citric acid. Another option is to take supplements such as potassium citrate or calcium citrate, which provide citrates in concentrated forms.
Other Dietary Guidelines to Consider
# Eat more fiber
Besides calcium and citrates, other nutrients are thought to contribute to a reduced risk of calcium-oxalate stone formation. According to a Pubmed study, increased fiber intake has been linked to a lower risk of kidney stones as it helps decrease urinary calcium and oxalate excretion.
The same study claims that postmenopausal women who ate a diet high in fiber, fruits, and vegetables had a lower incidence of kidney stones.
Fruits and vegetables with the lowest oxalate content include avocado, mushrooms, white potatoes, radishes, Brussels sprouts, banana, cherries, grapes, apples, among a variety of other options.
# Explore this article for a more detailed list of oxalate-low foods
# Improve gut health
Calcium-oxalate stones have a bit to do with gastrointestinal status; specific bacteria in the gut are thought to be able to break down dietary oxalate, opening up the possibility of using probiotics to improve gut health in the hopes of preventing stone formation.
Oxalobacter formigens is a friendly anaerobic bacterium that has the ability to degrade oxalates and make them less available for absorption. Unfortunately, certain antibiotics, like as cipro, can destroy and disrupt this microbial function.
To support a healthy gut and potentially reduce the risk of stone formation, it is advisable to be cautious with antibiotic use and prioritize a well-balanced diet that includes fiber-rich foods, plant-based foods, and fermented foods that contain probiotics.(6)
# Electrolyte balance
Ultimately, kidney stones are the result of an electrolyte and chemical imbalance. Calcium is most involved, but maintaining proper levels of other electrolytes such as magnesium, potassium, and sodium is thought to help prevent stone formation.
When it comes to sodium, one teaspoon of salt a day is considered safe; otherwise, excess sodium can cause more calcium to leave the body and build up in the kidney.
Some studies suggest that vitamin K2 inhibits the growth of calcium oxalate crystals, implying that a deficiency in vitamin K2 could be a contributing factor in the development of kidney stones, but further research is needed to support these findings and establish a definitive link.
What foods are high in oxalates?
Because oxalates are present in a wide variety of foods, we cannot completely eliminate our intake without risking nutrient deficiencies. The good news is that you don't have to eliminate oxalate-rich foods from your diet; rather, if you're prone to kidney stones, you should limit your consumption.
It’s important to remember that including calcium-rich foods like milk and cheese in your meals can significantly reduce the formation of calcium oxalate stones. Calcium binds to oxalates, making them less available for absorption. Developing the habit of consuming calcium-rich foods with meals is highly beneficial, particularly for individuals who have a history of kidney stones or are prone to their formation.
Another important point to keep in mind is that the formation of stones is not solely determined by the overall oxalate content of foods, but also by their bioavailability, which refers to how easily the oxalate in these foods is absorbed by the body.
The foods highest in oxalates include, among many others:
- Spinach, rhubarb, beets (roots and greens), Swiss chard
- Chaga Mushroom Powder
- Almonds, cashews and peanuts
- Star fruit (carambola)
- Wheat bran
- Dark chocolate
- Excessive tea consumption, especially instant tea, which increases urinary oxalate four times more than brewed tea
# Explore this article for a more detailed list of oxalate-rich foods
The Outlines
1. Limit the consumption of oxalate-rich foods
2. Consume calcium-rich foods alongside your oxalate-rich meals
3. Include citrates in your diet (water lemon juice)
4. Maintain hydration by consuming at least 2.5 liters of fluids per day
5. Reduce your intake of animal protein and salt, and incorporate more vegetarian foods
6. Be mindful of antibiotic usage
7. Promote a healthy gut
8. Ensure your electrolytes are properly balanced
9. Increase your intake of fiber and magnesium
10. Maintain a well-balanced diet