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Having IBD can make us question a lot of things, especially our nutrition intake.  A common question that we get as IBD dietitians is if a low oxalate diet is suitable and recommended for a patient with IBD.  Continue to read on for more information!

What are oxalates?

Oxalates are compounds that bind to minerals and can be found in foods naturally.  Oxalates tend to have a bad rep because they are known for increasing the risk of kidney stones.  It is important to note that dietary consumption of oxalates is not always comparable to stone formation.  It can be difficult to know exactly how much dietary oxalate is consumed in relation to a specific kidney stone formation. 

What role do oxalates have in the digestive tract?

Oxalates contributing to kidney stones can be decreased with the help of oxalate-degrading bacteria found in the gut.  Furthermore, research has shown that up to 40% of these gut-containing bacteria can decrease oxalates (1).

Certain bacterial strains including Lactobacillus and Bifidobacterium can help absorb oxalates, thereby decreasing kidney stone formation.  The same goes when there is an insufficient amount of these oxalate degrading bacteria in the digestive tract, there is an increased risk of kidney stones. 

Oxalobacter Formigenes, a type of oxalate-degrading bacteria found in the digestive tract, is lower in individuals that have a history of kidney stones and taking antibiotics compared to those without kidney stones.  Interestingly, those who take an O. Formigenes probiotic and have a history of kidney stones respond poorly to this type of probiotic. (1)

Research has shown that taking generous amounts of antibiotics and having a  dietary intake that is high in sugar and fat can decrease these helpful oxalate-degrading bacteria sources making it more difficult for oxalates to be metabolized.  Furthermore, consuming prebiotics including inulin, can help break down oxalates. (1)

  • Foods rich in inulin include: asparagus, banana, artichoke, leeks, onion, garlic
  • Favorite supplement form of Inulin: Olipop (prebiotic soda), use code GUTLOVE for 15% off

Should IBD patients avoid oxalates?

Firstly, oxalates cannot be avoided entirely since a lot of our nutritious foods, including vegetables, have oxalates in them.  Secondly, while people with IBD have a higher risk of developing kidney stones, it doesn’t mean we need to follow a low oxalate diet.  We also know that a low oxalate diet is used cautiously in certain populations where people have a history of kidney stones.  Lastly, many nutrient-dense foods are beneficial for the digestive tract and contain higher levels of oxalates (spinach, dark chocolate, almonds, soy, avocados, etc.).  These plant-based foods are also important for our microbiome in helping to produce healthy bacteria and are abundant when consuming a diverse diet.  Remember to avoid restricting or eliminating an entire food group without discussing it with your dietitian.  There may be no reason to eliminate these foods and can create more harm than good.

Bottom Line

IBD patients who avoid high oxalate foods may be missing out on key nutrients.  It is common for IBD patients to avoid these foods due to fear of kidney stones.  At this time, it is not recommended to avoid high oxalate foods since they are not always the cause for kidney stones.  If you have a history of kidney stones, it’s important to speak with your healthcare team to explore other options besides restricting your diet.  Focus on expanding your diet and avoid unnecessary restrictions. 

Written by: Rebecca Goodrich, MS, RD, LD & Ashley Hurst, MS, RD, LD

Karamad D, Khosravi-Darani K, Khaneghah AM, Miller AW. Probiotic Oxalate-Degrading Bacteria: New Insight of Environmental Variables and Expression of the oxc and frc Genes on Oxalate Degradation Activity. Foods. 2022; 11(18):2876.