Weight Loss Surgery Can Lead to Kidney Stones

Obesity is a significant problem in our community and throughout the United States.

Most people can, with perseverance, lose weight by watching their diet and exercising regularly. Others find programs such as Weight Watchers® to be helpful. Sometimes, however, patients fail traditional weight loss methods, and go on to require weight loss, or bariatric, surgery. Unfortunately, patients who undergo bariatric surgery have, over time, an increased rise of developing kidney stones.

Stuck Between a Rock and a Hard Place

Calcium and oxalate are naturally absorbed by the gastrointestinal or GI tract. Following  weight loss surgery, patients tend to absorb less calcium from their GI tract. The end result is that higher levels of oxalate tend to occur in the urinary tract. Under the right circumstances, the oxalate will form crystals, which in turn can aggregate to form kidney stones.

5 Tips for Kidney Stone Prevention 

1.  Drink Up! 

Water is very important in kidney stone prevention. Weight loss surgery patients are taught to sip fluids throughout the day.

A general recommendation is consume at least 6-8 glasses of water each day. Water helps dilute oxalate in the urinary tract and prevent it from forming into crystals and stones.

2.  Limit Oxalate Containing Foods  

Black teas, nuts, and dark leafy greens contain significant amounts of oxalates.  Consumption of these types of high oxalate-containing foods should be limited. In addition, nuts are high in calories which can defeat your weight loss efforts.

3.  Decrease Sodium

Reducing sodium intake is important. In addition to setting the salt shaker down, reducing sodium can be accomplished by eating less processed meats and packaged foods. Limiting sodium to 1500 mg or less daily is a good start. You can learn about how much sodium a given food contains by referring to the product’s nutrition label.

4. Cut out Red Meat

Limiting animal protein consumption can be helpful. Following weight loss surgery, protein is emphasized as a high priority food, but that doesn’t mean that you are on a high protein diet. Most patients who have undergone weight loss surgery cannot eat large portions of animal protein. Therefore, exploring more plant-based protein like legumes (beans) isn’t a bad idea, and they tend to be tolerated well after weight loss surgery.

5.  Other Dietary Suggestions

Much of what is a written about kidney stone prevention is centered around foods to be avoided. I asked my friend, Erica Phelps, a registered dietician, for some meal suggestions that might be low in oxalate. Here are some of her suggestions:

•  A bowl of bean or lentil soup or vegetarian chili
•  Homemade  bean burgers 
  
•  Mixed dishes of brown rice or quinoa tossed with beans, diced peppers, and onions 
•  Lettuce salad topped with garbanzo beans (chickpeas), cucumbers, tomatoes, and a vinaigrette dressing. 

Most people don’t have the time to prepare dry beans from scratch. Canned beans can be a healthy option. Rinsing canned beans before using can significantly reduce their sodium content.

Lettuce salads, cabbage, cauliflower, asparagus, green beans, peppers, and all squash are low oxalate vegetable choices. Finally, green tea is a low oxalate alternative to black tea.

Enjoy a nice warm bowl of  vegetarian chili or bean soup.

Putting It All Together 

Oxalate stones are a potential side effect of gastric bypass surgery. Consuming water throughout the day, limiting your sodium intake, and eating a diet rich in plant-based protein are all healthy strategies that can help you manage your weight, and prevent kidney stones.