Politics and Medicine - Conflicting Views on Calcium and Vit D for Bone Health

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Conflicting Views on Calcium and Vit D for Bone Health

PeterB

2006-02-25, 9:42 pm

A recently concluded 7yr study suggests only a slight benefit in terms
of bone density in some post-menopausal women, following use of
supplemental calcium and vitamin D. The press is already reporting
this story in a way that is misleading and, once again, the actual
science is likely to be ignored. When researchers looked only at women
who took their supplements consistently (at least 80% of the time), the
rate of hip fracture was redued by 29%, which is anything but "slight."
[http://www.dailynews.com/news/ci_3513493]

A good expository article (pasted below) on the study results can be
found at:
http://www.nutraingredients.com/new...-d-calcium-ost=
eoporosis

Calcium, vitamin D supplements good for bones - if you take them
By Stephen Daniells

16/02/2006 - Consumer confusion over vitamin D and calcium seems likely
to grow, following claims from the Women's Health Initiative (WHI)
trial about their effect on bone health that oppose other studies.

The combination of vitamin D and calcium has long been recommended to
reduce the risk of bone fracture for older people, particularly those
at risk of or suffering from osteoporosis, which is estimated to affect
about 75 million people in Europe, the USA and Japan.
Use of these supplements is widely accepted by the general public, with
calcium reported to be the biggest seller in the US supplements
industry, with annual sales of about $993 (=80836) million in 2004,
according to the Nutrition Business Journal.

The new study poses a challenge to this acceptance by concluding that
calcium and vitamin D supplements did not reduce the risk of fractures
in post-menopausal women.

Published in the New England Journal of Medicine (Vol. 354, pp.
669-683), the study followed 36,282 post-menopausal women with an
average age of 62 at the start of the trial. Volunteers were randomly
assigned to receive 1000 mg of elemental calcium in the carbonate form
and 400 IU of vitamin D3 per day, or a placebo.

After an average of seven years of follow-up the scientists reported:
"Among healthy postmenopausal women, calcium with vitamin D
supplementation resulted in a small but significant improvement in hip
bone density, and did not significantly reduce hip fracture."

Such a sweeping generalisation is somewhat misleading however. If one
looks just at the 59 per cent of the participants who actually adhered
to the supplementation programme (assuming 80 per cent or more
compliance with taking the supplements), the data do, in fact,
highlight the benefits of dual vitamin D-calcium supplementation.

The number of fractures in this compliant group was 29 per cent lower
than placebo. This indicates that supplementation with calcium and
vitamin D did significantly reduce the risk of hip fracture, as has
been reported by other studies, but only if taken regularly.

The bone mineral density of the entire intervention group increased by
0=2E86 per cent after six years, and for those followed-up for nine
years, BMD increased by 1.06 per cent.

The strengths of this study lie in the large-scale, randomised,
double-blind, placebo-based design. However the authors recognise that
adherence to an intervention using a free-living population is
difficult.

Indeed, even though the placebo group was not given the supplements by
the researchers, they were free to use supplements on their own.
Sixty-four per cent of the placebo group had a daily calcium intake of
at least 800 mg from diet and supplements, and 42 per cent were
consuming at least 400 IU of vitamin D.

This suggests that the intervention and control groups were very
similar. With both groups consuming calcium and vitamin D, this could
explain why the incidence of overall fractures was less than envisaged
- the actual hip fracture rate was more than half that projected by
the researchers.

"The lower-than-projected hip-fracture rate reduced the power of the
study to approximately 48 per cent," wrote the research team, led by
Rebecca Jackson from Ohio State University.

In an accompanying editorial, Joel Finkelstein from the Massachusetts
General Hospital rightly points out: "There were several aspects of the
study design and characteristics of the study population that may have
reduced the chances of detecting a benefit of calcium and vitamin D."

It should be pointed out that many of the women were involved in the
other arms of the WHI trial, with 69 per cent of the women enrolled on
the Dietary Modification trial, 54 per cent enrolled on the Hormone
Therapy trial, and 14 per cent enrolled on both.

"The use of hormone-replacement therapy (HRT) among post-menopausal
women has declined dramatically [HRT is known to be potent against bone
resorption and weakening and can reduce bone fracture]. Thus, the
widespread use of HRT in the current study limits the ability to
generalise the results," he said.

Another limitation, the dose of vitamin D might have been too small to
initiate a response for all participants. Other studies have reported
no effect with 400 IU, but benefits have been reported for trials using
doses of 600 IU or more.

However, it seems plausible that the dose was not as significant as
adherence to the program. The data clearly show that women who
regularly took the vitamins had a 29 per cent reduction in hip
fractures.

Finkelstein finishes a well-balanced editorial by concluding: "It seems
reasonable that women consume the recommended daily levels of calcium
and vitamin D through diet, supplements, or both. But one message is
clear: calcium with vitamin D supplementation by itself is not enough
to ensure optimal bone health."

This statement was echoed by Roger Francis, Professor of Geriatric
Medicine at the university of Newcastle, who told NutraIngredients.com:
"This study shows that vitamin D and calcium supplementation would not
work as a public health measure, because vitamin D - calcium trials
have notoriously poor adherence."

Professor Francis pointed out however that an earlier French study
(Scand J Rheumatol Suppl. 1996 Vol. 103, pp. 75-78) reported that
calcium and vitamin D supplements given to elderly women significantly
reduced the risk of hip fracture. This sample population was much older
than the WHI population.

The current EU recommended daily intake of calcium is 800 mg, with an
upper safe limit of 2500 mg. Vitamin D has a RDI of 400 IU, although
campaigners are calling for an increase to 1000 IU, half the upper safe
limit recommended by the EU and US.

In the US, the DRI (dietary reference intake) for calcium is 1000mg for
adults aged 19 to 50, and 1200mg from 51 to 70. For vitamin D it is
five micrograms per day, rising to 10 after the age of 50.

According to the International Osteoporosis Foundation, the total
direct cost of osteoporotic fractures is =8031.7 billion ($37.6) in
Europe, and $17.5 (=8014.7) billion in the US (2002 figure).

=A9 2001/2006 - Decision News Media SAS - All Rights Reserved.

vernon

2006-02-25, 9:42 pm

"PeterB" <pkm@mytrashmail.com> wrote in message
news:1140098956.204698.116230@g43g2000cwa.googlegroups.com...
A recently concluded 7yr study suggests only a slight benefit in terms
of bone density in some post-menopausal women, following use of
supplemental calcium and vitamin D.

A totally useless study by a totally useless college.
They have no idea what double blind or controlled environments mean.

Over half of the participants were taking supplements prior and during the
tests. These were not separated from the others to make two different
tests.

Peter Moran

2006-02-25, 9:43 pm

"vernon" <here@here.com> wrote in message
news:43f49230$0$32260$9a6e19ea@unlimited.newshosting.com...
>
> "PeterB" <pkm@mytrashmail.com> wrote in message
> news:1140098956.204698.116230@g43g2000cwa.googlegroups.com...
> A recently concluded 7yr study suggests only a slight benefit in terms
> of bone density in some post-menopausal women, following use of
> supplemental calcium and vitamin D.
>
> A totally useless study by a totally useless college.
> They have no idea what double blind or controlled environments mean.

Huh? The patients were randomised to receive either VitaminD and calcium
or matching placebo. So it was a controlled trial with blinding of both
the patients and also those assessing the patients for fracture. One can
argue that even that is scarcely necessary in a study looking at strongly
objective end-points such as fracture

And what sinister motive could these researchers possibly have for doing a
shoddy study? This is a major public health issue.
..
>
> Over half of the participants were taking supplements prior and during the
> tests. These were not separated from the others to make two different
> tests. >

They were retrospectively, and this was when the main statistically
significant findings were obtained. Also prerandomisation Vitamin D levels
had no effect on results. The study strongly suggests that vitamin D and
calcium will help reduce the risk of fracture.

From the abstract ----

"Censoring data from women when they ceased to adhere to the study
medication reduced the hazard ratio for hip fracture to 0.71 (95 percent
confidence interval, 0.52 to 0.97). Effects did not vary significantly
according to prerandomization serum vitamin D levels."

The full abstract ---
Jackson, Rebecca D.; LaCroix, Andrea Z.; Gass, Margery; Wallace,
Robert B.; Robbins, John; Lewis, Cora E.; Bassford, Tamsen; Beresford,
Shirley A.A.; Black, Henry R.; Blanchette, Patricia; Bonds, Denise E.;
Brunner, Robert L.; Brzyski, Robert G.; Caan, Bette; Cauley, Jane A.;
Chlebowski, Rowan T.; Cummings, Steven R.; Granek, Iris; Hays, Jennifer;
Heiss, Gerardo; Hendrix, Susan L.; Howard, Barbara V.; Hsia, Judith;
Hubbell, F. Allan; Johnson, Karen C.; Judd, Howard; Kotchen, Jane Morley;
Kuller, Lewis H.; Langer, Robert D.; Lasser, Norman L.; Limacher, Marian C.;
Ludlam, Shari; Manson, JoAnn E.; Margolis, Karen L.; McGowan, Joan; Ockene,
Judith K.; O'Sullivan, Mary Jo; Phillips, Lawrence; Prentice, Ross L.;
Sarto, Gloria E.; Stefanick, Marcia L.; Van Horn, Linda; Wactawski-Wende,
Jean; Whitlock, Evelyn; Anderson, Garnet L.; Assaf, Annlouise R.; Barad,
David

Institution For the Women's Health Initiative Investigators*
Address reprint requests to Dr. Jackson at the Division of
Endocrinology, Ohio State University, 485 McCampbell, 1581 Dodd Dr.,
Columbus, OH 43210, or at jackson.20@osu.edu.
*The Women's Health Initiative investigators are listed in Appendix 1.
The authors' affiliations are listed in Appendix 2.

Title Calcium plus Vitamin D Supplementation and the Risk of
Fractures.[Article]

Source New England Journal of Medicine. 354(7):669-683, February 16,
2006.

Abstract Background: The efficacy of calcium with vitamin D
supplementation for preventing hip and other fractures in healthy
postmenopausal women remains equivocal.

Methods: We recruited 36,282 postmenopausal women, 50 to 79 years of
age, who were already enrolled in a Women's Health Initiative (WHI) clinical
trial. We randomly assigned participants to receive 1000 mg of calcium
carbonate with 400 IU of vitamin D(3)) daily or placebo. Fractures were
ascertained for an average follow-up period of 7.0 years. Bone density was
measured at three WHI centers.

Results: Hip bone density was 1.06 percent higher in the calcium plus
vitamin D group than in the placebo group (P<0.01). Intention-to-treat
analysis indicated that participants receiving calcium plus vitamin D
supplementation had a hazard ratio of 0.88 for hip fracture (95 percent
confidence interval, 0.72 to 1.08), 0.90 for clinical spine fracture (0.74
to 1.10), and 0.96 for total fractures (0.91 to 1.02). The risk of renal
calculi increased with calcium plus vitamin D (hazard ratio, 1.17; 95
percent confidence interval, 1.02 to 1.34). Censoring data from women when
they ceased to adhere to the study medication reduced the hazard ratio for
hip fracture to 0.71 (95 percent confidence interval, 0.52 to 0.97). Effects
did not vary significantly according to prerandomization serum vitamin D
levels.

Conclusions: Among healthy postmenopausal women, calcium with vitamin
D supplementation resulted in a small but significant improvement in hip
bone density, did not significantly reduce hip fracture, and increased the
risk of kidney stones. (ClinicalTrials.gov number, NCT00000611.)

N Engl J Med 2006;354: 669-83.

Peter Moran

>

Skeptic

2006-02-25, 9:43 pm

"Peter Moran" <pmoranATbordernet.com.au> wrote in message
news:43f4db46$0$25844$afc38c87@news.optusnet.com.au...
>
> "vernon" <here@here.com> wrote in message
> news:43f49230$0$32260$9a6e19ea@unlimited.newshosting.com...
>
> Huh? The patients were randomised

RansomiZed.

PeterB

2006-02-25, 9:43 pm

Peter Moran wrote:
> "vernon" <here@here.com> wrote in message
> news:43f49230$0$32260$9a6e19ea@unlimited.newshosting.com...
>
> Huh? The patients were randomised to receive either VitaminD and calcium
> or matching placebo. So it was a controlled trial with blinding of both
> the patients and also those assessing the patients for fracture. One can
> argue that even that is scarcely necessary in a study looking at strongly
> objective end-points such as fracture
>
> And what sinister motive could these researchers possibly have for doing a
> shoddy study? This is a major public health issue.
> .
>
> They were retrospectively, and this was when the main statistically
> significant findings were obtained. Also prerandomisation Vitamin D levels
> had no effect on results. The study strongly suggests that vitamin D and
> calcium will help reduce the risk of fracture.
>
>
>
> From the abstract ----
>
> "Censoring data from women when they ceased to adhere to the study
> medication reduced the hazard ratio for hip fracture to 0.71 (95 percent
> confidence interval, 0.52 to 0.97). Effects did not vary significantly
> according to prerandomization serum vitamin D levels."
>
> The full abstract ---
> Jackson, Rebecca D.; LaCroix, Andrea Z.; Gass, Margery; Wallace,
> Robert B.; Robbins, John; Lewis, Cora E.; Bassford, Tamsen; Beresford,
> Shirley A.A.; Black, Henry R.; Blanchette, Patricia; Bonds, Denise E.;
> Brunner, Robert L.; Brzyski, Robert G.; Caan, Bette; Cauley, Jane A.;
> Chlebowski, Rowan T.; Cummings, Steven R.; Granek, Iris; Hays, Jennifer;
> Heiss, Gerardo; Hendrix, Susan L.; Howard, Barbara V.; Hsia, Judith;
> Hubbell, F. Allan; Johnson, Karen C.; Judd, Howard; Kotchen, Jane Morley;
> Kuller, Lewis H.; Langer, Robert D.; Lasser, Norman L.; Limacher, Marian C.;
> Ludlam, Shari; Manson, JoAnn E.; Margolis, Karen L.; McGowan, Joan; Ockene,
> Judith K.; O'Sullivan, Mary Jo; Phillips, Lawrence; Prentice, Ross L.;
> Sarto, Gloria E.; Stefanick, Marcia L.; Van Horn, Linda; Wactawski-Wende,
> Jean; Whitlock, Evelyn; Anderson, Garnet L.; Assaf, Annlouise R.; Barad,
> David
>
> Institution For the Women's Health Initiative Investigators*
> Address reprint requests to Dr. Jackson at the Division of
> Endocrinology, Ohio State University, 485 McCampbell, 1581 Dodd Dr.,
> Columbus, OH 43210, or at jackson.20@osu.edu.
> *The Women's Health Initiative investigators are listed in Appendix 1.
> The authors' affiliations are listed in Appendix 2.
>
> Title Calcium plus Vitamin D Supplementation and the Risk of
> Fractures.[Article]
>
> Source New England Journal of Medicine. 354(7):669-683, February 16,
> 2006.
>
> Abstract Background: The efficacy of calcium with vitamin D
> supplementation for preventing hip and other fractures in healthy
> postmenopausal women remains equivocal.
>
> Methods: We recruited 36,282 postmenopausal women, 50 to 79 years of
> age, who were already enrolled in a Women's Health Initiative (WHI) clinical
> trial. We randomly assigned participants to receive 1000 mg of calcium
> carbonate with 400 IU of vitamin D(3)) daily or placebo. Fractures were
> ascertained for an average follow-up period of 7.0 years. Bone density was
> measured at three WHI centers.
>
> Results: Hip bone density was 1.06 percent higher in the calcium plus
> vitamin D group than in the placebo group (P<0.01). Intention-to-treat
> analysis indicated that participants receiving calcium plus vitamin D
> supplementation had a hazard ratio of 0.88 for hip fracture (95 percent
> confidence interval, 0.72 to 1.08), 0.90 for clinical spine fracture (0.74
> to 1.10), and 0.96 for total fractures (0.91 to 1.02). The risk of renal
> calculi increased with calcium plus vitamin D (hazard ratio, 1.17; 95
> percent confidence interval, 1.02 to 1.34). Censoring data from women when
> they ceased to adhere to the study medication reduced the hazard ratio for
> hip fracture to 0.71 (95 percent confidence interval, 0.52 to 0.97). Effects
> did not vary significantly according to prerandomization serum vitamin D
> levels.
>
> Conclusions: Among healthy postmenopausal women, calcium with vitamin
> D supplementation resulted in a small but significant improvement in hip
> bone density, did not significantly reduce hip fracture, and increased the
> risk of kidney stones. (ClinicalTrials.gov number, NCT00000611.)
>
> N Engl J Med 2006;354: 669-83.
>
The problem wasn't so much the study protocols (though they were
confusing to the press) but the study conclusion, which fails to relay
the substantial benefit in fracture risk to those who reliably take
their supplements. The media, as always, dutifully ignored the fine
print.

PeterB