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Does a Bone Healthy diet contribute to Kidney Stones?

Recently a follower of my Eating Plan expressed concern that foods that are good for your bones might also contribute to kidney stone formation. I do not believe a bone healthy diet will contribute to kidney stone formation. There is evidence that calcium supplements contribute to kidney stones but not calcium rich foods.

Here is some advise from the National Kidney Foundation on diet and kidney stones that helps clarify how the 2 dietary approaches compare:

  • One of the most important things you can do is to drink plenty of water.
  • Oxalate is naturally found in many foods, including fruits and vegetables. Peanuts, rhubarb, spinach, beets, chocolate and sweet potatoes are high in oxalate. People who form calcium oxalate stones, the leading type of kidney stones, may benefit from moderating (not eliminating) their intake of these foods. A common misconception is that cutting the oxalate-rich foods totally from your diet will reduce your chances of forming calcium oxalate kidney stones, however omitting these foods from your diet causes you to miss out on some healthy foods. Most kidney stones are formed when oxalate binds to calcium while urine is being produced by the kidneys. So a better approach is to consume calcium and oxalate-rich foods together during a meal so that oxalate and calcium are more likely to bind to one another in the stomach and intestines before the kidneys begin processing it, making it less likely that kidney stones will form.
  • According to the National Kidney Foundation, “Calcium is Not the Enemy”, but there is a misunderstanding, even among some health professionals, that calcium is the main culprit in the formation of calcium-oxalate stones. According to Nephrologist Dr. Roy Jhagroo, “A diet low in calcium actually increases one's risk of developing kidney stones”. So don't reduce your calcium intake but do look at the sodium in your diet and cut back if it is high.
  • Another common type of kidney stone is a uric acid stone. Red meat, organ meats, and shellfish have high concentrations of a natural chemical compound known as purines. A high purine intake can result in a higher production of uric acid and ultimately make it easier for uric acid stones to form. To reduce your chances of uric acid stones, cut down on high-purine foods such as red meat, organ meats, and shellfish, and follow a healthy diet that contains mostly vegetables and fruits, whole grains, and low fat dairy products. Limit sugar-sweetened foods and drinks, especially those that contain high fructose corn syrup. Limit alcohol because it can increase uric acid levels in the blood and avoid crash diets since they can also increase uric acid levels. Eat more fruits and vegetables, and less animal protein to reduce the chance of stone formation.

So a bone healthy diet and a kidney stone preventing diet are very similar in that they both promote lots of fruits and vegetables and moderate amounts of animal protein. To reduce your chances of kidney stones just be sure to combine high oxalate foods with calcium foods in the same meal, watch your sodium and drinks lots of water.  If you want more details go to www.kidney.org or talk to your nephrologist or a dietitian/nutritionist who specializes in this area.

Photo used with permission from the Journal of the Academy of Nutrition and Dietetics.
Photo taken by Kristen Keith RD, LD, MS 

posted 12/18/2018