Claim: Soda causes kidney stones

This is junk science because…

… the statistical associations of interest are weak, but most tellingly the association for the highest exposure category (i.e., one or more sodas consumed per day) is NOT statistically significant when adjusted for confounding risk factors. So the more kidney stone risk factors are considered, the weaker the association with soda becomes.

Also, the study relies on sporadic, self-reported data (i.e., let’s see, hmmm… how much soda did I drink four years ago). So the researchers really don’t know how accurate their exposure data are.

The study also involves multiple comparisons and the perpetual junk science machine known as the Nurses Health Study (i.e., secret data of dubious quality that is never verified).

The media release is below.

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Sugar-sweetened beverages associated with increased kidney stone risk

New research from Brigham and Women’s Hospital finds that some beverages may be more helpful than others when it comes to preventing recurrent kidney stones

Boston – Twenty percent of American males and 10 percent of American females will experience a kidney stone at some point in their lifetime. Often, these patients will be advised to drink more fluids as a way to prevent future stone formation. Now, new research from Brigham and Women’s Hospital finds that some beverages may be more helpful than others when it comes to preventing recurrent kidney stones. In a study published online May 15, 2013 in the Clinical Journal of the American Society of Nephrology (CJASN), researchers report that the consumption of sugar sweetened soda and punch is associated with a higher risk of stone formation.

“Our study found that the relation between fluid intake and kidney stones may be dependent on the type of beverage consumed,” explained Gary Curhan, MD, ScD, a physician in the Channing Division of Network Medicine at BWH and senior author of this study. “We found that higher consumption of sugar-sweetened drinks was associated with a higher incidence of kidney stones.”

The researchers analyzed data from three ongoing cohorts, the Health Professionals Follow-Up Study (HPFS), and both the Nurses’ Health Study I (NHS I) and II (NHS II). The total analysis involved 194,095 participants over a median follow-up of more than 8 years. Participants in all the three cohorts had been asked to complete biennial questionnaires with information on medical history, lifestyle, and medication. Questions on diet were updated every four years. They found that participants who consumed one or more sugar-sweetened cola servings per day had a 23 percent higher risk of developing kidney stones compared with those participants consuming less than one serving per week. This was true for consuming sugar-sweetened non cola as well, such as punch. They also found that some beverages, such as coffee, tea and orange juice, were associated with a lower risk of stone formation.

“Our prospective study confirms that some beverages are associated with a lower risk of kidney stone formation, whereas others are associated with a higher risk,” explained Pietro Manuel Ferraro, MD, a physician at the Catholic University of the Sacred Heart of Rome and corresponding author of this study. “Although higher total fluid intake reduces the risk of stone formation, this information about individual beverages may be useful for general practitioners seeking to implement strategies to reduce stone formation in their patients.”

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4 responses to “Claim: Soda causes kidney stones

  1. What about diet sodas and sugar sweetened tea or coffee?

  2. With a certain degree of confidence (as I helped Dr. Yasushi Nakagawa identify the genetic code for the kidney stone inhibitor he discovered) I can tell you that the only cause of kidney stones in mammals is the absence of said inhibitor (which happens to be a short splice variant of uromodulin).

    The prevalence of kidney stone disease in genetically diverse human populations (think U.S.), is about 6-7% (iirc). It is much higher in inbred populations, almost reaching Mendelian proportions. Those who don’t have the gene or fail to express it develop troublesome kidney stones sooner or later. Sooner, if they are vegetarians drinking hard water.

    “Our study found that the relation between fluid intake and kidney stones may be dependent on the type of beverage consumed.”

    Maybe. We know that Pepsi is a rich source of calcium.

    The best beverage, if you have this genetic defect, is distilled water. It is also important that you don’t consume foods high in citric or oxalic acid (which rules out things like lemons, oranges, tomatoes, and spinach — among many other things).

    There is only one cause of kidney stones: citrates and oxalates of calcium form crystals that are not soluble in water. Everybody has these crystals in his urine, but those of us who have a functional kidney stone inhibitor are able to limit the size of those crystals and they never grow enough to block renal tubules.

  3. My daughter developed kidney stones as a result of school bullying.
    She became terrified of being caught in the school restroom, so she abstained from drinking (water, sodas or anything else!) until after school, so she would not have to pee.
    Because of chronic *dehydration* her body would reabsorb water in her kidneys, forming calciferous kidney stones.

    • Oh dear. Has she recovered?

      When I was in school, I think I could count the number of times I visited its restroom. Not that anybody limited my access to it; I could just go for days without needing one. And I did not limit my water intake in any way; on the contrary, I received warnings from doctors and concerned relatives about the dangers of drinking too much (which I ignored). Whenever I did get to pee in a civilized restroom and cared to pay attention, I would often note scarce and very dark urine. My theory was that I lost more water through breathing and perspiration than through my kidneys. I never worried about being properly hydrated; I drank all I could when I had access to water but did not worry much when it was not available. Whether I had to pee ten times a day or once in a couple days, it always seemed to be a different shade of normal. It never hurt.

      So I’m surprised to hear that reabsorption can hurt, although it makes perfect sense.

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