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Does Calcium Cause Kidney
Stones?
The following is an excerpt from The Willner
Window Radio Program, originally broadcast
on WOR Radio (710 AM, in NY), on August
19, 2012.
Arnie: We are going to try to clarify another
of the common misleading statements about
the so-called dangers of nutritional supple-
ments today. Last week, we touched on fish
oils, blood thinners and anti-coagulant med-
ications. If you missed it, you can go to our
website, www.willner.com and listen to the
mp3 files. Click on the "radio shows" tab.
Don: Today, we are going to talk about cal-
cium and kidney stones. You hear it all the
time–be careful about taking calcium supple-
ments because it will increase your odds of
getting kidney stones!
And, amazingly enough, there are people
who, when they hear this, forget all about
the overwhelming list of essential, life saving,
benefits of calcium, and proceed to increase
their risk of osteoporisis, various cancers, ele-
vated cholesterol, obesity, preeclampsia, peri-
odontal disease, PMS, etc by not taking their
calcium supplements.
The sad thing is that this scare tactic about
calcium and kidney stones is totally mislead-
ing. We will tell you why that is.
Arnie: First, what is a kidney stone, and
what does it have to do with calcium?
It's called a kidney stone because that's
what it resembles–a small stone, composed
of minerals, that forms in the kidney. It can
cause pain, bleeding in the urine, and block-
age of the ureters, the tubes that connect the
kidney and the bladder, allowing for the flow
of urine. Some people have kidney stones,
and never even know it.
Having a kidney stone attack is not a fun
thing. We certainly don't want to do anything
to increase our risk of having this unpleasant
experience. So what are the factors that can
increase our chances of kidney stones?
According the the Mayo Clinic, they are as
follows:
1. It runs in the family. If someone else in
your family has kidney stones, you are more
likely to have them as well.
2. Being over age 40.
3. Being a man, as kidney stones are more
common in men.
4. Not drinking enough water. Not diluting
the urine with water throughout the day
increases the risk.
5. Being obese increases your risk.
6. Digestive diseases and surgery–gastric
bypass, inflammatory bowel disease or
chronic diarrhea and similar conditions can
alter the absorption of nutrients affecting
stone formation.
7. Various medical conditions such as renal
tubular acidosis, cystinuria, hyperparathy-
roidism, certain medications and urinary tract
infections.
8. Certain diets. I left this one for last, on
purpose. Here is exactly what the Mayo
Clinic said under the heading, "Certain diets."
Quote " Eating a diet that's high in protein,
sodium and sugar may increase your risk of
some types of kidney stones. This is especial-
ly true with a high-sodium diet. Too much
sodium in your diet increases the amount of
calcium your kidneys must filter and signifi-
cantly increases your risk of kidney stones."
Don: That's interesting, isn't it. No mention
of dietary calcium as a risk factor. No men-
tion of calcium supplements. Instead, it
seems they are much more concerned about
the effect of a high sodium diet, which can
indirectly impact the role of the kidneys and
calcium.
Well, get ready for a surprise. They do not
mention a high calcium diet for a very good
reason. It turns out that research shows that a
high calcium diet actually _decreases_ the
risk of kidney stones!
Yes, you heard me right. A high calcium
diet reduces the risk of kidney stones.
Arnie: There was a study published in the
New England Journal of Medicine, April 1,
1997. This study is one of the sources of the
misleading, half-truth about calcium supple-
ments supposedly increasing the risk of kid-
ney stones. It's an excellent example of how
you can cherry pick your facts to support
your agenda. Here's the full story.
The study was a large, epidemiological
study of 91,731 nurses who had never had
kidney stones and were between the ages of
34 and 59 at the beginning of the study in
1980. The nurses were followed with ques-
tionnaires for 12 years. The questionnaires
asked specifically about dietary habits, calci-
um supplements, and kidney stones. The
dietary intake of calcium also was estimated
from the dietary habits.
Don: During the 12 years of the study, 864
nurses developed kidney stones for the first
time. That's about 0.1% per year. There was
a strong association between higher dietary
calcium intake and kidney stones–but, sur-
prise surprise-- the greater the intake of calci-
um, the fewer the nurses developing stones.
Nurses taking the highest amount of dietary
calcium were half as likely to develop stones
as women taking the lowest amount of
dietary calcium.
Arnie: Now, here is the tricky part. Among
nurses taking calcium supplements (in addi-
tion to their dietary calcium) the risk of
developing stones was greater than among
nurses not taking calcium supplements.
Specifically, nurses taking supplemental cal-
cium were 20% more likely to develop
stones as women not taking supplemental
calcium.
Don: So hold on a minute. Those who had
the highest intake of dietary calcium and the
lowest incidence of kidney stones, but, at the
same time, those who took calcium supple-
ments had an increased incidence? Does that
make sense? Does calcium in supplements
have the opposite effect of calcium in food?
Arnie: No, Don, it does not make sense.
And, unless you have some ulterior motive,
like an anti-supplement bias, you would
acknowledge that. In fact, that is exactly
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