Low Carb diet & kidney stones?TIME article : LC Research/Media Forum : Active Low-Carber Forums

#1 ^

Thu, Aug-29-02, 21:50

exba

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Low Carb diet & kidney stones?TIME article

I was interested to see the thread related to the recent TIME magazine article. What struck me, though, was the little blurb in relation to low-carb diets that "a recent study, however, suggests that low-carb diets that are also high in protein favor the formation of kidney stones".
I was particulary alarmed as my husband and I have only recently started the Atkins diet to try to control his elevated BP and serum cholesterol/triglyceride levels. Within 3 weeks of the program, my husband passed a kidney stone. This was his first ever, and I wondered if there was any relation to the low-carb diet.
I wish TIME magazine had provided the study that they are referencing so I could research it for myself.

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#2 ^

Fri, Aug-30-02, 06:37

doreen T doreen T is offline

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hi there exba,

If there's an article, research piece or "study" about low-carbing, high-protein and/or fat diets, chances are good it's been posted right here in our Research/ Media forum.

The "study" about protein and kidney stones was posted recently; check it out - I wonder what they think we eat????

The theories that protein and ketones cause kidney stones or somehow damage our kidneys (and livers and arteries and brains and etc, etc ....) surface now and then, promoted by the anti-lowcarb gang. But they're just that ... theories. They have yet to be PROVEN. This "study" was based on a small sampling (10 subjects) and the diet was totally skewed

Excess protein CAN stress kidneys that are already damaged from chronic infection, poorly controlled high blood sugar in diabetes, alcoholism or decreased blood flow (due to massive blood loss such as an accident or major burns, or from poor circulation/ hardening of the arteries). The key word here is EXCESS ... and none of the major low-carb programs promote excess protein, only ADEQUATE protein.

Doreen

#3 ^

Fri, Aug-30-02, 07:48

Sheldon

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The comment by Andrew Weil, which is posted at "I wonder what they think we eat," is revealing. Given his low-fat background, everyone should look at it and file it away in memory. It will be useful in your diet discussions with friends.

Sheldon

#4 ^

Fri, Aug-30-02, 13:48

Jamesw

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http://members.aol.com/rogerbaxtr/p...html#Preventing

That same Harvard study found that:

Those with the highest consumption of potassium, from eating fruits and vegetables, had only half the risk of stones;

A high fluid intake was associated with a 29 percent lower risk; and

Those who ate the most animal protein had a 33 percent higher risk of developing kidney stones.

#5 ^

Sat, Aug-31-02, 08:20

Dana114

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exba,

You do realize that kidney stones take YEARS to formulate, don't you? Your husband's kidney stone could not have formed in the 3 weeks he was on Atkins, but on his previous diet.

#6 ^

Sat, Aug-31-02, 09:14

Lisa N Lisa N is offline

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I agree with Dana.

It was likely just a coincidence since kidney stones cannot possibly form in a matter of a few weeks time. Judging from what James had to say about the Harvard study, if you are drinking plenty of water and eating veggies high in potassium (or taking a potassium supplement), you risks of kidney stones on low carb would be no higher (or perhaps even a bit lower) than on any other way of eating.
Studies of children who use a ketogenic diet to control epilepsy (which is much more limiting of carbs than what most of us do) did seem to indicate a higher risk for kidney stones...BUT...there are many other factors that could have influenced that. If my kids are any indication of average fluid intake for children, I'd be more inclined to blame a low fluid intake than the ketogenic diet for kidney stone formation. I have to constantly remind my kids to drink enough or they don't get nearly enough, especially in the summer when it's hot.

#7 ^

Sat, Aug-31-02, 10:06

doreen T doreen T is offline

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Quote:

Originally posted by Jamesw
http://members.aol.com/rogerbaxtr/p...html#Preventing

That same Harvard study found that:

Those with the highest consumption of potassium, from eating fruits and vegetables, had only half the risk of stones;

A high fluid intake was associated with a 29 percent lower risk; and

Those who ate the most animal protein had a 33 percent higher risk of developing kidney stones.

Hmmm ... I checked out the link provided. The site is a personal, non-scientific collection of bits of information gleaned from here and there. Many of the links on that site are broken, and references are scarce or inaccurate.

The quote which is given above followed this paragraph:

Quote:

However it must be quickly noted here that calcium supplements increase kidney stone risks according to the Annuals of Internal Medicine, March 1997. High normal dietary calcium reduces kidney stones by 35 percent, but high calcium from non-foods - like calcium supplements - actually increase the risk of kidney stones by 20 percent.

First, I tried the link given there, and it took me to a commercial website selling vitamins and supplements, and nothing about kidney stones or research papers.

So I hunted around on my own. Went to the Annals of Internal Medicine website, and located the article, which was in the April 1 '97 issue, not March ... Comparison of Dietary Calcium with Supplemental Calcium and Other Nutrients as Factors Affecting the Risk for Kidney Stones in Women. There is no mention of protein anywhere in the results of the study.

Quote:

Results: During 903 849 person-years of follow-up, 864 cases of kidney stones were documented. After adjustment for potential risk factors, intake of dietary calcium was inversely associated with risk for kidney stones and intake of supplemental calcium was positively associated with risk. The relative risk for stone formation in women in the highest quintile of dietary calcium intake compared with women in the lowest quintile was 0.65 (95% CI, 0.50 to 0.83). The relative risk in women who took supplemental calcium compared with women who did not was 1.20 (CI, 1.02 to 1.41). In 67% of women who took supplemental calcium, the calcium either was not consumed with a meal or was consumed with meals whose oxalate content was probably low. Other dietary factors showed the following relative risks among women in the highest quintile of intake compared with those in the lowest quintile: sucrose, 1.52 (CI, 1.18 to 1.96); sodium, 1.30 (CI, 1.05 to 1.62); fluid, 0.61 (CI, 0.48 to 0.78); and potassium, 0.65 (CI, 0.51 to 0.84).

Please note the very last sentence:

Other dietary factors showed the following relative risks among women in the highest quintile of intake compared with those in the lowest quintile: sucrose 1.52 ... sodium, 1.30 ... fluid, 0.61 ... and potassium, 0.65.

Sucrose?? My my

Apparently the study was flawed anyway, according to a letter to the editor of the Annals of Internal Medicine, posted in November '97.

Quote:

.... I suggest that Curhan and colleagues overinterpreted their data and that Coe and colleagues were insufficiently critical in analyzing the data. One test of inferences from such observational data is the finding of at least an ordinal relation between dose and effect. This relation is clearly seen for food calcium in Curhan and colleagues' Table 3, with a highly significant downward trend in risk for stone development as calcium intake increases. However, such a relation is not found with supplemental calcium (the authors' Table 4). Only the group with the lowest supplement intake had a significant increase in risk for stones. The groups with higher intakes had no increase at all. Persons showing an increase consumed less than 500 mg of supplemental calcium per day (that is, the type of intake likely to be associated with multivitamin supplements that contain minerals). In contrast, supplement intakes greater than 500 mg/d generally reflect ingestion of true calcium supplements. Thus, if the effect described by Curhan and colleagues is anything other than a chance occurrence, it may reflect some other component of the types of supplements likely to be represented in the low-intake group rather than calcium.

Finally, it may be worth recalling that the standard therapy for the renal stone disease of intestinal hyperoxalosis is precisely a high calcium intake (in the form of calcium supplements). The reason, consistent with the explanation given for the efficacy of dietary calcium, is the complexation of oxalate in the intestine by unabsorbed dietary calcium and prevention of its absorption; this process in turn reduces the renal oxalate burden.

Robert P. Heaney, MD
Creighton University
Omaha, NE 68178

So it seems that neither animal protein nor calcium supplements taken at sufficient levels have been positively associated with increased risk of developing kidney stones. RDA for calcium is 1000 to 1200 mg per day for adults.

It would also appear that sucrose (table sugar) is positively associated with increased risk of kidney stone formation, even more so than sodium or fluids.

Doreen