Can Tofu and Spinach cause Kidney Stones?

When you have kidney stones, you may need to make major adjustments to your diet. Foods you may have eaten for years and considered healthy are suddenly off limits. Tofu and spinach are examples of supposedly healthy foods that must be re-examined. Let’s look at why you may need to remove these items from your diet.

The Spinach and Tofu Kidney Stones Connection

Why would either spinach or tofu be harmful to people with kidney stones? Based on its rich nutritional profile, you might think spinach is good for the kidneys. Tofu is also widely recommended as a high-quality plant-based protein. The reason has to do with oxalates, a term you may have learned if you’ve been diagnosed with calcium oxalate stones.

Calcium oxalate stones form when calcium binds with compounds known as oxalates, which are present in many foods. A tricky point about oxalates is that foods normally labeled as healthy can be high in oxalate. Spinach, along with other green leafy vegetables, falls into this category. Soy products, including tofu, soy milk, and soy-based veggie burgers, are also high in oxalate.

Spinach is one of the foods at the top of the high oxalate list. A single serving of 3.5 ounces or 100 grams can contain over 600 milligrams of oxalate. To put this into perspective, if you are on a low oxalate diet, you should not be consuming more than 100 milligrams of oxalate daily. Some low oxalate diets even recommend fewer than 50 milligrams daily. Raw spinach is especially high in oxalate. Cooked spinach reduces the oxalate content by about 50%. However, even this is too high if you’re on a low oxalate diet.

Soy products such as tofu, while not as high in oxalate as spinach, are also foods to avoid if you have calcium oxalate stones. A 3-ounce serving of tofu contains over 200 milligrams of oxalate, still more than you should be consuming all day with calcium oxalate stones. A cup of soy milk or soy yogurt has even more, around 300 milligrams. A dish such as stir-fried tofu with spinach, while it may sound healthy, is one of the worst things to eat for anyone on a low oxalate diet.

Guidelines For a Calcium Oxalate Kidney Stones Diet

Following a low oxalate diet is about more than avoiding a couple of foods. You need to get familiar with the oxalate content of all the foods you typically eat. The following are more examples of common foods that are high in oxalate.

Swiss Chard
Chocolate
Almonds
Rhubarb
Raspberries
Beets
Textured Vegetable Protein or TVP, often used as a meat substitute.

Does Spinach Cause Kidney Stones?

Research is clear that spinach and other high oxalate foods should be avoided if you already have kidney stones. However, there is no evidence that spinach causes kidney stones. One study found that eating more spinach does not increase your risk of developing kidney stones. Overall, spinach is nutritious and healthy, as long as you don’t have calcium oxalate kidney stones. If you’ve had calcium oxalate stones in the past, however, you may want to limit spinach and other oxalate-rich foods.

The Best Diet For Uric Acid Stones

Next to calcium oxalate stones, the most common variety is uric acid stones. These require a different type of diet. Rather than avoiding oxalate, you have to watch for foods that increase acidity in the urine. The main culprit in this area is animal proteins such as meat and seafood. Alcoholic beverages also increase acidity.

Food to eat in acidity-based diets includes fruits and vegetables, whole grains, and limited fats and carbohydrates. You don’t have to worry about oxalate content, so foods such as spinach, other leafy greens, and soy products are fine.

For all types of kidney stones, it’s important to drink plenty of water. Hydration flushes your kidneys, making it easier to pass any kidney stones that may have formed.

Eat the Right Diet For Kidney Stones

Depending on the type of kidney stones you have, you may need to eliminate foods such as spinach, tofu, and others. Be sure to get an accurate diagnosis and find the diet that’s appropriate. You’ll be able to get rid of kidney stones faster if you avoid foods that contribute to their formation.