This post was originally written during my 2 1/2 year tenure as a blogger for Health Goes Strong. This site was deactivated on July 1, 2013, but you can read the post here.
RESEARCH SHOWS CONNECTION BETWEEN DIETARY CALCIUM AND KIDNEY STONES IS BENEFICIAL, DOES NOT CAUSE KIDNEY STONES
The one thing everyone agrees with when discussing kidney stones is how painful they are. Having had them twice in my life I can confirm all reports about how excruciating they are. Childbirth was easier.
What is not so clear is the connection between calcium and kidney stones.
Some new research provides much needed insight into the causes of kidney stones and what we can do to prevent the pain that goes with them.
What Are Kidney Stones?
The most common types of kidney stones are composed of either calcium oxalate or calcium phosphate. Calcium, oxalate and phosphate are all minerals that are part of a healthy diet and are normally dissolved in the urine. Under certain conditions, however, they can precipitate out of solution and form small insoluble stones that are passed through the urinary tract unnoticed.
The biggest contributor to the formation of these stones is not drinking enough fluids. The more fluids we drink the more urine we produce, and the more urine we produce the more diluted the minerals will become in our urine.
Another contributor is a high salt diet. When we have excess sodium in our bodies the kidneys must use all available fluids to dilute the sodium so it can be excreted in the urine. That increases the risk that other minerals will precipitate and form stones.
If stones do form and they become too big to pass easily, they can cause the notorious back pain. This, along with the other tell-tale signs of a kidney problem blood such as blood in the urine and pain while urinating, should send you straight to the doctor.
Does Calcium Cause Kidney Stones?
Even though too little fluid and too much sodium are the leading causes of kidney stones, it was widely believed that calcium was the problem since most kidney stones contain calcium. But studies have shown calcium is not the culprit.
People who have the most calcium in their diets are much less likely to suffer from kidney stones than those who eat very few calcium-rich foods. Here’s why.
We need calcium to remove oxalate, the other half of what makes up most kidney stones. Oxalate is found in many fruits, vegetables, nuts, grains and soy products, plus cocoa and black tea. There’s really no avoiding it and maintaining a healthy diet. But the more calcium we have in our digestive tracts, the more it can bind with oxalate and remove it from the body before it can settle in the kidneys.
If we cut back too much on calcium, oxalate can accumulate in the kidneys and create stones with the available calcium.
The key here is that it is dietary calcium that helps, such as that found in dairy products and other calcium-rich foods. Calcium supplements are not as effective and may contribute to stone formation if taken in large quantities.
What Else Can Cause Kidney Stones?
The National Institute of Diabetes and Digestive Diseases and Kidney Diseases (NIDDK) has an Information Clearinghouse that answers all of the questions you may have about kidney stones, and more. The key takeaways for anyone wondering what their risk might be are these:
- Family history of hypercalciuria, a condition of high calcium levels in the urine
- Personal history of kidney stones
- Personal history of gout or high uric acid levels in blood or urine
- Regular use of diuretics (medications to help the kidneys remove fluids from the body)
- Regular use of calcium-based antacids
- High dose calcium supplements in people who don’t have osteoporosis (more than 2000 mg/day)
- High dose vitamin D supplements in people who are not deficient (more than 2000 I.U/day)
Check back here for my next blog about another stony issue, gall stones.