In our day to day lives, kidney stones are not a common topic of conversation. But high oxalate levels, which can increase the risk of kidney stones, is more common than we think. And unfortunately, the kidneys are not the only tissues that can be affected: high oxalate levels may contribute to body pain, thyroid issues, bladder symptoms and more. Thankfully, understanding what leads to high oxalates helps to inform our daily habits, manage healthy oxalate levels and build resilience in our health.

In North America, the risk of getting kidney stones for men is close to 20% and almost 10% in women. Maybe the most well-known aspect of kidney stones are the excruciating pain that some experience while passing the stone. Last week, the actor, Liam Hemsworth described his experience being hospitalized for a kidney stone as “one of the most painful weeks of my life.” He attributed the formation of the kidney stone to his diet.

What are kidney stones and oxalates?
There are multiple different types of kidney stones with 80% of them being calcium oxalate stones. Since this is the most common type of stone, I will focus today’s discussion on oxalate types. Oxalates are compounds in plant foods like vegetables, nuts and beans. And once eaten and absorbed, oxalates circulate in our blood. Due to the pH of our blood, oxalate molecules have a -2 charge to it. That means it’s ready to bind to minerals that have a +2 charge (like calcium, zinc, magnesium and many other minerals) and form crystals like calcium oxalate crystals, or if larger, stones. The body regulates calcium levels in the blood quite strictly so calcium oxalate crystallization is mostly driven by how high the oxalate levels are.

Although the pain of kidney stones is quite well known, the negative health impacts of high oxalate levels are rarely discussed. Oxalate crystals may also contribute to muscle aches, joint pain, bladder symptoms, groin pain, thyroid dysfunctions and even eye or mood issues.

How do oxalate levels increase?

  1. Diet – largest exposure
  2. Yeast/Fungus – like Candida or mold colonization
  3. Metabolic imbalances
    1. Like Vitamin B6 deficiency
    2. Rare genetic enzyme defects

How can I reduce the risk of kidney stones and high oxalates?

Stay well hydrated Drink water throughout the day. Volume of water (in ounces) to drink: about  ½ your body weight in pounds. And avoid pop as this has been linked to increased risk of stone formation.

Whole foods diet with a variety of fruits and vegetables Although the largest exposure of oxalates are from dietary plant foods, we know that eating more fruits and vegetables reduces our risk of kidney stones compared to eating lots of animal protein. So it’s important to keep plant foods in our daily diet. Mr. Hemsworth reported that he was eating “5 handfuls of spinach” in a daily morning smoothie. We certainly don’t know if this was the cause of his kidney stone, but in general, eating a variety of foods (ie. choosing what’s in season or choosing different leafy green vegetables each time we go shopping) is a great way to prevent nutrient deficiencies and excess oxalate intake. Whole foods diet also helps to avoid excess salt from processed foods. If you know you have high oxalate levels, be aware of which foods contain high levels of oxalates so you can make sure to avoid consuming large amounts of them every day.

Some high oxalate foods:

Swiss chard
Parsley, raw
Sweet potatoes
Lemon & Lime peel
Soy protein, Tofu
Black pepper
Instant coffee
Tea, black & rosehip
Wheat germ

Continue to eat calcium rich foods
When hearing that kidney stones are composed of calcium oxalate, some people worry about too much calcium in their diet. Calcium is not only crucial for bone health, calcium in your food actually helps to prevent high oxalates in the blood. And low calcium intake may actually increase the risk of stone formation. Green vegetables, sesame seeds and dairy are good sources of calcium.

Balance gut flora and Vitamin B6 An overgrowth of yeast, fungus and/or mold can increase the risk of high oxalates. This is made worse by Vitamin B6 deficiency. These are often difficult to identify without specialized tests.

If you have a history of kidney stones or have been told you have oxalates in your urine, you may already be hydrating and avoiding high oxalate foods (or even following a low oxalate diet). But for some people this isn’t enough. Knowing what your oxalate levels are and where they are coming from can help to finally reduce the pain and symptoms. Specialized testing helps to measure oxalate levels and identify contributing factors like yeast/mold overgrowth, dietary oxalates and vitamin B6 deficiency.

Oxalates are a naturally occurring compound in many nutritious plant foods. Staying hydrated, emphasizing variety in a whole foods diet and addressing vitamin and gut flora imbalances help to maintain healthy oxalate levels, avoid pain and allow smooth functioning of the body.

Stay safe and healthy,
Dr. Carin