Impact of Soy Milk on Calcium Oxalate Kidney Stones: What You Need to Know

Q: Impact of Soy Milk on Calcium Oxalate Kidney Stones: What You Need to Know

Hello： The article mentions, "This is another good reason to keep dietary oxalate low – 50 to 100 mg if possible." This means that for patients prone to kidney stones, it is advisable to maintain dietary oxalate intake below 100 mg. <br>A cup of soy milk contains approximately 20

How does soy milk affect calcium oxalate kidney stones?

I have some questions for the doctor.
I have a history of kidney stones, and recently I researched dietary considerations for kidney stones online.
I found some articles stating that soy milk, unlike other soybean products, has a very low oxalate content, while other articles claim that the oxalate in soy milk can bind with its calcium, making it less absorbable.
Some even state that drinking "red tea with soy milk" can allow the calcium from soy milk to counteract the oxalate from red tea, thus not increasing the risk of stone formation.
However, an article from the University of Chicago titled "How To Eat A Low Oxalate Diet" (https://kidneystones.uchicago.edu/how-to-eat-a-low-oxalate-diet/) includes a food oxalate reference chart based on certain experimental results, indicating that soy milk is classified as "very high" in oxalate content, with 20 mg per cup (originally considered "low"), and the article does not recommend its consumption.
The sources I found online claiming low oxalate content in soy milk are quite outdated.
Should I reduce my soy milk intake? Additionally, some articles suggest that certain food combinations can form calcium oxalate in the intestines, preventing oxalate absorption, but they do not consider the differences in oxalate and calcium quantities (for example, vegetable and tofu soup, or consuming oxalate-containing foods while supplementing with calcium).
Should I avoid those foods, or should I evaluate how much oxalate or calcium remains after the chemical reaction? Is there a way to determine what type of stone I have if I currently do not have a stone sample? Thank you!

Mr. Chen, 20~29 year old female. Ask Date: 2018/09/17

Dr. Wu Hongjie reply Internal Medicine

Hello: The article mentions, "This is another good reason to keep dietary oxalate low – 50 to 100 mg if possible." This means that for patients prone to kidney stones, it is advisable to maintain dietary oxalate intake below 100 mg.
A cup of soy milk contains approximately 20 mg of oxalate.
If soy milk is your only source of oxalate and your daily intake does not exceed this amount, you are unlikely to exceed the limit, unless you are also consuming other oxalate-rich foods.
If you might exceed the limit, it is important to be cautious to avoid stone formation.
After passing a stone, it is essential to analyze its composition to understand its makeup.
Otherwise, it is not possible to determine the food combinations that lead to calcium oxalate formation, which can bind in the gastrointestinal tract and be excreted in feces.
If you have had bowel surgery or other reasons that shorten the intestines, the amount of oxalate in the urine may increase.
The most critical factors influencing stone formation are daily water intake and urine volume, followed by calcium and oxalate levels, as well as urine pH.
Therefore, correcting dietary and hydration habits should be the primary goal.
Wishing you health and safety.

Reply Date: 2018/09/17

More Info

When it comes to managing kidney stones, particularly calcium oxalate stones, dietary choices play a significant role. Your inquiry about soy milk and its relationship with calcium oxalate stones is quite pertinent, especially given the conflicting information available online.

Firstly, it is essential to understand the composition of soy milk. Soy milk is derived from soybeans and is often considered a good alternative to dairy milk for those who are lactose intolerant or prefer plant-based diets. The nutritional profile of soy milk can vary, but it typically contains lower levels of oxalate compared to other plant-based beverages. However, the oxalate content can differ based on the processing methods and the specific brand of soy milk.

Regarding the interaction between oxalate and calcium, it is true that when calcium and oxalate are consumed together in the gastrointestinal tract, they can bind to form calcium oxalate, which is then excreted in the feces. This process can potentially reduce the amount of oxalate that is absorbed into the bloodstream and subsequently filtered by the kidneys. Therefore, consuming calcium-rich foods or beverages alongside oxalate-rich foods can be beneficial in reducing the risk of stone formation.

The idea that soy milk can mitigate the effects of oxalate from beverages like red tea is based on this principle. However, it is crucial to consider the actual amounts of calcium and oxalate present in the foods you are consuming. If the calcium content in soy milk is not sufficient to bind with the oxalate from red tea, the risk of absorption and subsequent stone formation may still be present.

As for the varying reports on the oxalate content in soy milk, it is essential to rely on recent and credible sources. The article from the University of Chicago you mentioned indicates that soy milk may have a higher oxalate content than previously thought. This discrepancy highlights the importance of staying updated with current research, as dietary recommendations can change as new data emerges.

In terms of your dietary choices, moderation is key. If you enjoy soy milk, it may not be necessary to eliminate it entirely, but you should be mindful of your overall oxalate intake from all sources. It would be prudent to balance your diet with low-oxalate foods and ensure adequate calcium intake from various sources, including dairy or fortified alternatives, to help mitigate the risk of stone formation.

Regarding your question about identifying the type of kidney stones you have had in the past, this typically requires analysis of the stone itself. If you do not have a stone sample, your healthcare provider may suggest imaging studies or urine tests to assess your risk factors and help determine the type of stones you may be prone to developing.

In conclusion, while soy milk can be part of a balanced diet, it is essential to consider its oxalate content and how it fits into your overall dietary pattern. Consulting with a healthcare professional or a registered dietitian who specializes in kidney health can provide personalized recommendations tailored to your specific needs and history of kidney stones. Staying hydrated and maintaining a balanced diet rich in fruits, vegetables, and adequate calcium can significantly contribute to reducing the risk of kidney stones.

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