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A. Calcium
oxalate and urate stones are the commonest kinds of kidney stones.
Before you hang the rap on oxalate I hope your pathologist has properly
identified your stone as oxalate and not urate.
My question
now is what other plant sources of protein I should turn to. I have
never been overly fond of beans in general, which is partly why
I concentrated so heavily on soy foods (that and all the coverage
about how good soy is for you!). I enjoy tabouli salad and Thai
dishes based on wheat gluten and wonder whether there are similar
(presumably low-oxalate) avenues, in addition to the beans I realize
I'll have to start eating more of, that I can pursue.
Actually, beans
contain purines and since that substance breaks down to uric acid,
beans are considered more of a risk for gout and urate renal stones
than for oxalate stones although in my experience they cause neither.
However, one can get along perfectly well without beans. The basis
for a healthy vegan diet should be fresh vegetables, (particularly
leafy greens), and fruit, with Calorie needs filled in by raw seeds,
nuts, avocados, grains, starches, beans and whatever other whole
plant food agrees with you.
However, your
question inspired me to a web search and some USDA nutrient data
on oxalate. I downloaded it and sorted from high to low oxalate
values. Here it is:
"http://www.nal.usda.gov/fnic/foodcomp/Data/Other/oxalic.html
Oxalic Acid
Content of Selected Vegetables
This table was
originally published in Agriculture Handbook No. 8-11, Vegetables
and Vegetable Products, 1984.
Vegetable Oxalic
acid (g/100 g)
Parsley 1.70
Chives 1.48
Purslane 1.31
Cassava 1.26
Amaranth 1.09
Spinach 0.97
Beet leaves 0.61
Carrot 0.50
Radish 0.48
Collards 0.45
Beans, snap 0.36
Brussels sprouts 0.36
Garlic 0.36
Lettuce 0.33
Watercress 0.31
Sweet potato 0.24
Turnip 0.21
Chicory 0.21
Broccoli 0.19
Celery 0.19
Eggplant 0.19
Cauliflower 0.15
Asparagus 0.13
Endive 0.11
Cabbage 0.10
Tomato 0.05
Pea 0.05
Turnip greens 0.05
Potato 0.05
Onion 0.05
Okra 0.05
Pepper 0.04
Parsnip 0.04
Rutabaga 0.03
Squash 0.02
Kale 0.02
Cucumbers 0.02
Corn, sweet 0.01
Coriander 0.01
It would appear
that somebody gave you a bum rap on eggplant. I wasn't able to find
acceptable references to the oxalate content of soybean and it doesn't
appear in the above list. There was some chatter about tofu being
a risk for kidney stone but it seemed to be based on calcium content.
While some tofu is soybean soup, precipitated with calcium chloride
or sulfate (and thus has a high calcium content), soybeans per se
don't make the calcium/Calorie sort until #486 in the USDA SR13
database. Most likely they are a poor source of both calcium and
oxalate. Taro leaf, undoubtedly the grand champ for oxalate content,
also does not appear in the list.
I was an ER
physician for 30 years in Honolulu, surely the kidney stone capital
of the world. Our urologists didn't think diet had anything to do
with stone formation. However, to the persevering patient I would
confide that in my opinion the best way to avoid kidney stones was
to avoid organ meats and dairy, thus cutting the risk for both urate
and calcium stones respectively, and to drink lots of water, thus
diluting whatever bad humors in the urinary tract were still likely
to precipitate and form stones.
Here are two
references:
Good luck,
-William Harris,
M.D.
*****************
Urol Int 1982;37(6):394-9
The pattern
of urinary stone disease in Leeds and in the United Kingdom in relation
to animal protein intake during the period 1960-1980.
Robertson WG,
Peacock M
Studies on the
occurrence of urinary stone disease in Leeds between 1960 and 1980
show that there was an increase in the number of stones formed during
the period 1960-1970, a fall between 1972 and a subsequent rise
between 1977 and 1980. The fluctuations in stone incidence were
accounted for almost entirely by changes in the number of 'pure'
calcium oxalate stones and, to a lesser extent, the number of uric
acid stones produced. The incidence patterns of these types of stone
closely reflected changes in the consumption of animal protein in
the population as a whole during the same period. There were no
parallel changes either in the number of stones consisting of a
mixture of calcium oxalate and calcium phosphate or in the number
of infection stones.
PMID: 7179602,
UI: 83094692
Eur Urol 1982;8(6):334-9
Prevalence of
urinary stone disease in vegetarians.
Robertson WG,
Peacock M, Marshall DH
A study was
carried out to determine the effect of a low animal protein diet,
such as taken by vegetarians, on the risk of urinary stone disease.
A nation-wide survey of vegetarians in the UK showed that the prevalence
of urinary stone formation is 40-60% of that predicted for a group
of individuals taken from the general population and matched for
age, sex and social class with the vegetarians. The findings support
the hypothesis that a diet low in animal protein reduces the risk
of urinary stone formation.
***********
Here's your
American Chemical Society reference. Note that no data is given
here on the oxalate content of soybeans, only on the content of
processed and usually concentrated soy products :
September 4,
2001
Source: American
Chemical Society (http://www.acs.org/)
Date: Posted 8/29/2001
Too Much Soy
Could Lead To Kidney Stones
New research
indicates that soybeans and soy-based foods, a staple in the diets
of many health-conscious consumers, may promote kidney stones in
those prone to the painful condition. The finding will be published
in the September issue of the Journal of Agricultural and Food Chemistry,
a peer-reviewed journal of the American Chemical Society, the world's
largest scientific society. The researchers measured nearly a dozen
varieties of soybeans for oxalate, a compound that can bind with
calcium in the kidney to form kidney stones. They also tested 13
types of soy-based foods, finding enough oxalate in each to potentially
cause problems for people with a history of kidney stones, according
to Linda Massey, Ph.D., at Washington State University in Spokane.
The amount of oxalate in the commercial products easily eclipsed
the American Dietetic Association's 10 milligram-per-serving recommendation
for patients with kidney stones, with some foods reaching up to
50 times higher than the suggested limit, she noted.
"Under
these guidelines, no soybean or soy-[based] food tested could be
recommended for consumption by patients with a personal history
of kidney stones," she said.
No one had previously
examined soy foods for oxalate, thus the researchers are the first
to identify oxalate in store-bought products like tofu, soy cheese
and soy drinks. Other foods, such as spinach and rhubarb, also contain
significant oxalate levels, but are not as widely consumed for their
presumed health benefits, Massey said.
During their
testing, the researchers found the highest oxalate levels in textured
soy protein, which contains up to 638 milligrams of oxalate per
85-gram serving. Soy cheese had the lowest oxalate content, at 16
milligrams per serving. Spinach, measured during previous research,
has approximately 543 milligrams per one-cup (2 oz. fresh) serving.
Soy, a natural
source of protein, fiber and healthy oils, is used to enhance a
myriad of foods, ranging from hamburgers to ice cream. It can be
ground into flour and used in a variety of grain products, or formed
into chunks and ground like meat. Soy is also being studied for
its potential to lower cholesterol, reduce bone loss and prevent
breast cancer. The U.S. Food and Drug Administration recently approved
a new label on foods containing at least 6.25 grams of soy protein
per serving that boasts of a reduced risk of cardiovascular disease.
Oxalate, however,
cannot be metabolized by the body and is excreted only through urine,
Massey said. The compound has no nutritional value, but binds to
calcium to form a mass (kidney stones) that can block the urinary
system, she said. Further research is needed to find types of soybeans
with less oxalate, or to develop a processing method to remove the
compound before it reaches consumers, she added.
No one knows
precisely why kidney stones occur in particular individuals. But
Massey said high levels of oxalate in the urine increase the risk
and those with a family history of the ailment are more likely to
suffer from the condition; individuals with a low probability of
kidney stones are unlikely to be affected by oxalate in soy-based
foods.
More than one
million people were diagnosed with kidney stones in the United States
in 1996, the most recent available data, according to the National
Institutes of Health. Stones can range in size from the diameter
of a grain of rice to the width of a golf ball. An estimated 10
percent of the U.S. population, mostly men, will develop a kidney
stone at some point in their lives, according to the NIH.
********************
American Chemical
Society -- connected to National Cattlemen's Beef Association? http://www.beefnutrition.org/media/press_050201.shtml
Also...see the
American Chemical Society website - http://membership.acs.org/C/CentralArizona/014Newsletter.htm
"Cattlemen's
Association Barbecue" -- among the "events" listed.
Someone suggested
tainted research but neither of these URLs are presently available
online.
 William
Harris MD received a degree in physics from the University of
California Berkeley, where he earned Phi Beta Kappa honors. He received
his degree in medicine from the University of California at San
Francisco, and received his postgraduate training at San Diego County
Hospital. He holds a Medical License in the State of Hawaii. He
has been an Emergency Department physican since 1963, and the Director
of the Kaiser Permanente Vegan Lifestyle Clinic on Oahu until his
retirement in 1998. Dr. Harris is the author of The Scientific Basis
of Vegetarianism.
In addition, he was the 1950 Big Ten Trampoline Champion, is
an accomplished hangglider and commercial pilot, and at age 70 became
a skydiver with 108 jumps to date. Dr. Harris has been vegetarian
since 1950, and vegan since 1963.
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