Quelle:
Medline Abstract
Darmkrebs
und Osteoporose:
Calcium-
und Vitamin D-Therapie enttäuschten
Zu
den Standardempfehlungen die Ärzte älteren Frauen geben gehört
der Rat nach Beginn der Wechseljahre Calcium und Vitamin D einzunehmen,
um die Wahrscheinlichkeit von Knochenbrüchen zu reduzieren. Quasi
als erwünschte Nebenwirkung wurde den Frauen in der Vergangenheit
ein Rückgang des Darmkrebs-Risikos in Aussicht gestellt.
Nun belegen zwei neue Studien, daß beide Hoffnungen durch Einnahme
der Nahrungs-Ergänzungsmittel nicht einzulösen sind. Zwar
nahm die Knochendichte unter langjähriger Calcium- und Vitamin-D-Gabe
tatsächlich um magere 1% zu, doch die Zahl der Knochenbrüche
ging dadurch nicht wie erhofft zurück. Die erhöhte Knochendichte
von 1% wird andererseits mit einer deutlichen Zunahme von Nierensteinen
erkauft.
Wurde
Calcium und Vitamin D von den älteren Frauen sieben Jahre
lang eingenommen, so konnte diese Therapie die Häufigkeit von
bösartigen Darmtumoren nicht senken. Möglicherweise ist dafür
eine weitaus längere Einnahme erforderlich.
N Engl J Med. 2006 Feb 16;354(7):669-83
Erratum in: N Engl J Med. 2006 Mar 9;354(10):1102.
Comment in: N Engl J Med. 2006 Feb 16;354(7):750-2.
Calcium
plus vitamin D supplementation and the risk of fractures.
Jackson
RD, LaCroix AZ, Gass M, Wallace RB, Robbins J, Lewis CE, Bassford
T, Beresford SA, Black HR, Blanchette P, Bonds DE, Brunner RL,
Brzyski RG, Caan B, Cauley JA, Chlebowski RT, Cummings SR, Granek
I, Hays J, Heiss G, Hendrix SL, Howard BV, Hsia J, Hubbell FA,
Johnson KC, Judd H, Kotchen JM, Kuller LH, Langer RD, Lasser NL,
Limacher MC, Ludlam S, Manson JE, Margolis KL, McGowan J, Ockene
JK, O'Sullivan MJ, Phillips L, Prentice RL, Sarto GE, Stefanick
ML, Van Horn L, Wactawski-Wende J, Whitlock E, Anderson GL, Assaf
AR, Barad D; Women's Health Initiative Investigators.
Division
of Endocrinology, Ohio State University, 485 McCampbell, 1581
Dodd Dr., Columbus, OH 43210, USA. jackson.20@osu.edu
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 elemental [corrected] calcium as calcium carbonate
with 400 IU of vitamin D3 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.).
****
1:
N Engl J Med. 2006 Feb 16;354(7):684-96.
Erratum in: N Engl J Med. 2006 Mar 9;354(10):1102.
Comment in: N Engl J Med. 2006 Feb 16;354(7):752-4.
Calcium
plus vitamin D supplementation and the risk of colorectal cancer.
Wactawski-Wende J, Kotchen JM, Anderson GL, Assaf AR, Brunner
RL, O'Sullivan MJ, Margolis KL, Ockene JK, Phillips L, Pottern
L, Prentice RL, Robbins J, Rohan TE, Sarto GE, Sharma S, Stefanick
ML, Van Horn L, Wallace RB, Whitlock E, Bassford T, Beresford
SA, Black HR, Bonds DE, Brzyski RG, Caan B, Chlebowski RT, Cochrane
B, Garland C, Gass M, Hays J, Heiss G, Hendrix SL, Howard BV,
Hsia J, Hubbell FA, Jackson RD, Johnson KC, Judd H, Kooperberg
CL, Kuller LH, LaCroix AZ, Lane DS, Langer RD, Lasser NL, Lewis
CE, Limacher MC, Manson JE; Women's Health Initiative Investigators.
Department
of Social and Preventive Medicine, University at Buffalo, 270
Farber Hall, Buffalo, NY 14214, USA.
jww@buffalo.edu
BACKGROUND: Higher intake of calcium and vitamin D has been associated with a reduced
risk of colorectal cancer in epidemiologic studies and polyp recurrence
in polyp-prevention trials. However, randomized-trial evidence
that calcium with vitamin D supplementation is beneficial in the
primary prevention of colorectal cancer is lacking.
METHODS:
We conducted a randomized, double-blind, placebo-controlled trial
involving 36,282 postmenopausal women from 40 Women's Health Initiative
centers: 18,176 women received 500 mg of elemental calcium as
calcium carbonate with 200 IU of vitamin D3 [corrected] twice
daily (1000 mg of elemental calcium and 400 IU of vitamin D3)
and 18,106 received a matching placebo for an average of 7.0 years.
The incidence of pathologically confirmed colorectal cancer was
the designated secondary outcome. Baseline levels of serum 25-hydroxyvitamin
D were assessed in a nested case-control study.
RESULTS:
The incidence of invasive colorectal cancer did not differ significantly
between women assigned to calcium plus vitamin D supplementation
and those assigned to placebo (168 and 154 cases; hazard ratio,
1.08; 95 percent confidence interval, 0.86 to 1.34; P=0.51), and
the tumor characteristics were similar in the two groups. The
frequency of colorectal-cancer screening and abdominal symptoms
was similar in the two groups. There were no significant treatment
interactions with baseline characteristics.
CONCLUSIONS: Daily supplementation of calcium with vitamin D for seven years had
no effect on the incidence of colorectal cancer among postmenopausal
women. The long latency associated with the development
of colorectal cancer, along with the seven-year duration of the
trial, may have contributed to this null finding. Ongoing follow-up
will assess the longer-term effect of this intervention.
(Clinical
Trials.gov number, NCT00000611.)
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