About twenty years ago, when I was suffering from recurrent kidney
stones, I researched this exact question. Since I didn't have the
Internet as a search tool then, I found the answer in an old-fashioned
sit-down library.
Calcium oxalate is the reason for draft beer being on the "to be
avoided" list for kidney stone patients. Many (though not all) kidney
stones are composed of calcium oxalate. Beer is a source of calcium
oxalate, and draft beer typically has a higher oxalate level than
other beers. Although reducing dietary intake of oxalates will not
necessarily prevent further stone formation, it is a precautionary
step that most physicians recommend. This doesn't mean that all the
foods which are on the no-no list must be avoided entirely, just that
moderation should be observed, and the daily intake of oxalates should
be minimized. If you choose to drink beer, you're probably better off
with bottled or canned beer.
Interestingly enough, calcium oxalate buildup during the brewing
process causes the formation of mineral deposits inside the brewing
equipment. This crystalline deposit is called "beerstore." It is
chemically quite similar to calcium-oxalate kidney stones (and, like
kidney stones, it can impede the proper operation of the plumbing).
"One of the most serious problems when brewing beer is calcium oxalate
formation in the beer. It causes scale on the process pipes and heat
exchangers, resulting in diminished efficiency of the heat exchangers
and elevated energy costs."
Novozymes: Calcium oxalate formation
http://www.novozymes.com/terms/TermsExplained.asp?termID=313
"Depending on stone composition, doctors can make dietary
recommendations, such as foods to avoid in the future, and set up
nutritional guidelines that fit the patient's lifestyle. For example,
calcium oxalate is the most common crystal found in stones. When too
much calcium oxalate accumulates in the urine, crystals form and a
kidney stone can develop. Doctors have found that patients who are
already susceptible to forming stones should limit intake of foods
high in oxalate--such as broccoli, spinach, asparagus, rhubarb,
oranges, various berries, apples, grapes, pineapples, beer, coffee,
tea, cocoa, cola drinks, and pepper, among other foods."
University of Chicago Hospitals: Kidney Stone
http://www.uchospitals.edu/specialties/kidney-stone/why-choose-us.html
Here is a good article that describes a low-oxalate diet:
Drugstore.com: Low-oxalate Diet
http://www.drugstore.com/qxc40738_333181_sespider/low_oxalate_diet/low_oxalate_diet.htm
This comes from the archives of the Homebrew Digest:
"Beer, it is true, may be harmful to stone formers or those
pre-disposed to form stones because of its oxalate content... Seeds in
general are a rich source of oxalate which is important for their
germination. Barley is no exception, although it has less oxalate than
wheat. Stout is around 10 mg/100 ml, so there are 30 odd mg in a
bottle... Not all calcium oxalate stone formers need avoid oxalate and
beer would not be a problem as they absorb very little oxalate from
the diet. The others who could potentially have a problem because they
absorb more oxalate from their diet, should be wary. Not a great deal
is known about how well oxalate in beer can be absorbed. The content
of calcium, magnesium and other ions could affect how available it is
for absorption. Transit time through the small intestine is another
factor to consider and perhaps beer is less harmful when consumed on
an empty stomach rather than with food, as it may pass thru quicker.
There are lots of unknowns..."
Homebrew Digest: Beer and oxalates
http://hbd.org/hbd/archive/2492.html#2492-13
My Google search strategy:
Google Web Search: "kidney stones" beer oxalate
://www.google.com/search?hl=en&q=%22kidney+stones%22+beer+oxalate
Google Web Search: beerstore OR "beer-store" oxalate
://www.google.com/search?hl=en&q=beerstore+OR+%22beer-store%22+oxalate
I hope this is helpful! If anything is unclear or incomplete, please
request clarification; I'll be glad to offer further assistance before
you rate my answer.
Best regards,
pinkfreud |
