Kidney Stones: The Basics

green-healthy-foodUreterolithiasis, renal calculi, nephrolithiasis and kidney stone all mean the same thing:  agony.  The nurse told us the pain is equivalent to passing a five-pound canned ham through the southern end of the digestive system, with the lid opened.  If you’ve never experienced the long road to relief, thank the Creator for being excused.

What causes kidney stones?

There is no single cause, but a combination of factors.  The wrong balance of fluids, minerals and acids can put you on your knees faster than being knighted.  If urine has more crystal-making elements than the fluid can dilute, bingo, you have the makings of a stone…or stones.  In looking for a definitive cause, science has left no stone unturned.  No pun intended.  Beneath one of those stones is fluoride, having been fingered as causative a decade ago, but only in those with symptoms of skeletal fluorosis and the propensity to form stones in the first place (Singh, 2001).  That rules lots of us out.  Whether or not high doses of vitamin C are implicated in the formation of stones is debatable and based on the status of other nutrients.  By itself, vitamin C, chemically known as ascorbic acid, is able to be converted by the body into oxalates, which increases the likelihood of making oxalate stones among stone formers who take more than the recommended upper limit of 2000 mg of vitamin C a day (Massey, 2005). But you gotta be a stone former.  Is that like a mason?   Earlier research found that high intake of vitamin B6, pyridoxine, reduces the risk of stone formation from unrestricted doses of ascorbic acid (Curhan, 1999).   Up to 500 mg of pyridoxine a day was found to be useful in the control of elevated urinary oxalates (Mitwali, 1988).  In a study reported in the New England Journal of Medicine in the dark ages of the last century, the degree of oxaluria dictates the dosage of vitamin B6.  But the degree of supplementation depends on how much B6 comes from food (Yendt, 1985).

What are they made from?

Most stones (~80%) are calcium oxalate calculi, which crystallizes in a hurry.  It’s the stuff that forms a needle-like crust on the inside of a brewery container.  If you swallowed this material, you’d get really sick, and maybe die.  Calcium oxalate crystal formation is one of the effects of ingesting antifreeze.  A small dose of calcium oxalate will make your tongue burn and swell your throat shut.  This is what happens when the cat chews on a Dieffenbachia leaf in the living room window, and then requires a trip to the vet.

Some plants, including spinach, contain calcium oxalate in their leaves. If you’re a stone former, you might choose to avoid, or at least limit, raw spinach salads, although some researchers say it doesn’t matter, as long as you’re amply hydrated and your diet is sufficiently balanced to provide calcium and vitamin B6, both of which are found in spinach (Curhan, 1999).  A little baffling, huh?  After a stone passes through the urine and gets collected in that little strainer that painters use to get the globs out of a gallon of linen white, you’ll be asked to take that stone to the doctor so he can determine its makeup.  Then he’ll know what course of action to give you.

How do I prevent kidney stones?

If ever the proverbial ounce of prevention is worth a lot, this is the place.  Most experts agree that drinking fluids is the key.  Believe us when we say that a stone former is more than willing to increase his water intake, despite its lack of flavor.  If you need flavor, try lemon juice.  Counseling in this area is simple:  if you don’t drink enough water, you’ll experience this again.  That means you have to drink even when you’re not thirsty (McCauley, 2012).  Swapping soft drinks for water is prudent (Fink, 2009).

Increasing dietary calcium intake is inversely related to stone formation.  Supplemental calcium, on the other hand, may increase risk.  Dietary calcium blocks the amount of oxalates absorbed by the body, while supplements, especially if taken between meals, spill too much of the mineral into the urine.  If calcium supplementation is needed, take it with a meal to improve absorption.  We’re cautioned not to take more than 500 mg at a time, anyway.  It’s all about the timing (Curhan, 1997).

It’s believed that most stones form in the summer, when people are more likely to get dehydrated, so we’re admonished to drink ten to twelve glasses of water a day.  Other beverages, though, fare well in the prevention category.  Caffeinated and decaffeinated coffee, tea, and wine accounted for a decreased risk of stone formation, according to the Brigham and Women’s Hospital study of the 1990’s (Curhan, 1998).

Obesity increases the risk of kidney stones, but drastic weight loss measures that rely on high protein intake can stymie the good intentions.  So, too, can laxative abuse, rapid loss of lean tissue and, naturally, poor hydration.  A diet high in fruits and vegetables can alkalize urine enough to offset oxalate and uric acid stone formation ( Frassetto, 2011).  Produce is known for its magnesium content.  Intake of magnesium is related to reduced stone manufacture, and has been a recommendation since the 17th century.  Even without overt deficiency, magnesium intake, at 500 mg a day in the form of magnesium hydroxide, was shown to decrease stone formation, and it has no adverse side effects as long as it’s not overzealously done (Johansson, 1980 and 1982).  Too much magnesium may induce laxation.  That’s an individual response.   Later study learned that magnesium combined with vitamin B6 offered a substantial decline in the risk for oxalate stones (Rattan, 1994)

Kale, turnip greens, radishes, chard and other leafy greens, broccoli, Brussels sprouts, and cabbage are good sources of dietary calcium.  Almonds and cashews, pumpkin seeds, barley, quinoa, leafy greens, white and black beans are a few good sources of magnesium.  Since calcium and magnesium compete for occupancy in the body, with calcium the winner, magnesium supplementation is a good idea.  An Epsom salts bath allows magnesium levels to increase transdermally…and it’ll help you fall asleep.  Drink water.  Prevent stones.

References

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