Tea, coffee, wine (and more), and kidney stones

Saw an article about sugary drinks, tea drinking and kidney stones in World Tea News,* so I thought I might go back to the original paper on which it was based. 

An amazing photo from Wikipedia by GrammarFascist:
"The yellow object in the center of the image is a kidney stone composed of calcium oxalate. The sharp edges which cause pain and bleeding as such stones pass through the ureter are visible. The green stone at right is a sail-cut chrome tourmaline gemstone, and the kidney stone and gemstone are resting on a synthetic whetstone."

The article by Ferraro and colleagues** presents yet another analysis of the long-term data from the Nurses’ Health Studies I and II, and the Health Professionals Follow-Up Study. The focus of their analysis was the relationship of consumption of beverages of all kinds to the development of kidney stones. The usual recommendation to people with kidney stones is to drink plenty of fluids. The question is then: which fluids?

Turns out that plain water drunk more than once a day is protective, a good choice, but there are (possibly) better ones. So what are they?

Not tea, really — if you drink more than one cup a day, it may have a small effect (at least if you are a nurse or a physician).  In their discussion in the paper, the authors extol the virtues of tea, but the data only bear out an effect with more than one cup a day, and a slight effect at that. 

But coffee, yes, both caffeinated and decaffeinated, though caffeinated is better; and wine, both red and white, and beer.

Juices (apple, grapefruit, tomato juice, orange juice) and milk (whole and skim) are fairly neutral.

The baddies: sugared sodas and punch—they increase the risk!  Nothing said about sweet tea, but a good guess is that it may be like the sodas.

One of the questions not asked: relationship of fluid type to type of kidney stones—oxalate stones are the most common, but uric acid stones, associated with gout, can be made worse, not better, with alcohol. And of course the populations studied were limited demographically.

My bottom line: enjoy your tea, but don’t expect it to protect you from kidney stones…or cause kidney stones, either.

* http://worldteanews.com/tea-health-education/avoid-kidney-stones-skip-sugary-drinks

** Ferraro PM1, Taylor EN, Gambaro G, Curhan GC. Soda and other beverages and the risk of kidney stones. Clin J Am Soc Nephrol. 2013 Aug;8(8):1389-95. doi: 10.2215/CJN.11661112. Epub 2013 May 15.