Oxalates are natural compounds found in many plant-based foods. When you eat high oxalate foods, your body absorbs them in the digestive tract. Once in the bloodstream, minerals like calcium bind oxalates to form crystals that are excreted in urine. For some people, however, oxalates may build up and contribute to the formation of kidney stones.
Calcium oxalate stones are the most common type of kidney stone.
Calcium is vital for bone health and body function. However, sharp stones may form in the kidneys when calcium combines with oxalates.
Why Do Calcium Oxalate Stones Form?
Several factors contribute to the development of calcium oxalate stones:
- Not drinking enough water leads to concentrated urine. Being dehydrated makes it easier for calcium and oxalate to crystallize.
- Calcium binds to oxalates in the digestive tract, reducing their absorption into the bloodstream. Although it may seem counterintuitive, too little dietary calcium can raise oxalate levels.
- Some individuals naturally produce more oxalate in their bodies, which can contribute to stone formation. Conditions like excess oxalate in the urine, called hyperoxaluria, also increase the risk.
What Are High Oxalate Foods?
Certain foods contain significantly higher oxalate levels than others. If you're watching your intake, these are some of the highest sources:
- Vegetables: spinach, beet greens, Swiss chard, rhubarb, and okra
- Nuts and Seeds: Almonds, cashews, peanuts, and walnuts
- Grains: Whole wheat, quinoa, and buckwheat
- Fruits: Figs, raspberries, and dates
- Dark chocolate and cocoa powder
- Black tea
You don't have to cut foods from the list entirely. Instead, control your portions and pair them with calcium-rich foods. This way, you can lower the risk of stone formation.
If you're looking to reduce your oxalate intake, consider including more of these low-oxalate foods in your diet:
- Vegetables: Cabbage, cauliflower, cucumbers, zucchini, iceberg lettuce, and mushrooms
- Dairy and protein: Milk, yogurt, cheese, eggs, and lean meats
- Fruits: Apples, bananas, grapes, melons, and peaches
- Grains and starches: White rice, pasta, white bread, and corn-based products
The Role of Vitamin C in Oxalate Formation
Vitamin C helps with your immune function and adds antioxidant protection against free radicals. However, consuming it excessively, especially in supplement form, can increase oxalate levels in the body. This happens because your body converts excess vitamin C into oxalate. The oxalates are then excreted through urine, raising the risk of kidney stone formation.
Will I Know If I Have A Kidney Stone?
When calcium oxalate stones are small, they may pass unnoticed. However, larger stones can cause recognizable symptoms, including:
- Severe, sharp pain in the lower back, side, or abdomen
- Pain that radiates to the groin
- Blood in the urine
- Frequent or painful urination
- Nausea and vomiting
Managing oxalate intake is just one part of maintaining kidney health. If you've experienced kidney stones in the past or are at risk of developing them, it's important to talk to a urologist. A urologist can assess your risk and recommend dietary changes. They can also provide both preventative and treatment options if needed.
Schedule an appointment with one of our specialists to learn more.