<http://d
x.doi.org/10.1093/jnci/djj181>Low Vitamin D Levels
Associated with Increased Total Cancer Incidence
[<http://jncicancerspectrum.oupjournals.org/>Journal
of the National
Cancer Institute;
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Low levels of vitamin D may be associated with increased
total cancer
incidence and mortality in men, particularly for cancers of
the
digestive system, according to a study in the April 5 issue
of the
Journal of the National Cancer Institute.
Previous studies have suggested that sunlight exposure and
increased
vitamin D intake is associated with a reduced risk of
certain
cancers, particularly cancers involving the digestive
system. Thirty
minutes of sunlight exposure for a person with light skin
can produce
approximately 20,000 IU of vitamin D. Recent studies have
suggested
daily intake of vitamin D should be increased from 400 IU to
1000 IU.
Edward Giovannucci, M.D., Sc.D., of Harvard School of Public
Health,
and colleagues examined vitamin D exposure and cancer
incidence for
47,800 men in the Health Professionals Follow-Up Study
cohort.
Between 1986 and January 31, 2000, the authors documented
4286 cases
of cancer, and 2025 cancer deaths. They estimated vitamin D
levels by
recording each man's dietary intake and supplementation,
skin
pigmentation, adiposity, geographic residence, and
leisure-time
physical activity.
The authors observed that an increase in estimated vitamin D
levels
equivalent to 1500 IU of vitamin D daily, was associated
with a 17%
reduction in total cancer incidence, 29% reduction in total
cancer
mortality, and 43% and 45% reduction in incidence and
mortality from
digestive system cancers. Among men with the lowest vitamin
D
exposure, there were 758 cases of cancer diagnosed per
100,000 men
and 326 cancer deaths per 100,000 annually. Among men with
the
highest vitamin D exposure, there were 674 cancers diagnosed
per
100,000 men and 272 cancer deaths per 100,000. The authors
suggest
that low levels of vitamin D may be associated with
increased cancer
risk, and they suggest that daily supplementation with at
least 1500
IU of vitamin D may be required to optimize benefits on
cancer risk.
The authors write, "Confirming that vitamin D levels
indeed account
for the associations we observed is critical because current
health
recommendations typically discourage high intake of vitamin
D and
high levels of sun exposure, at least without use of
sunscreen, which
effectively blocks vitamin D production."
In an accompanying editorial, Gary G. Schwartz, Ph.D., of
Wake Forest
University in Winston-Salem, and William J. Blot, Ph.D., of
the
International Epidemiology Institute in Rockville,
compliment the
findings of Giovannucci and colleagues and suggest the
findings
support past epidemiologic observations. They write,
"The promising
results from both observational and laboratory studies
should usher
in a new era of intervention studies of vitamin D and cancer
risk.
Because many public health scientists are already clamoring
for
higher levels of vitamin D supplementation for bone and
other health,
randomized trials of vitamin D and cancer risk should be
undertaken
speedily. If the promise of vitamin D holds, a brief walk in
the sun
may turn out to be a step toward cancer prevention."
3. <http://jncicancerspectrum.oupjournals.org/>Journal
of the National Cancer Institute;
<http://jncicancerspectrum.oupjournals.org/
subscriptions/>Subscribe;
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Background: Vitamin D has potent anticancer properties,
especially
against digestive-system cancers. Many human studies have
used
geographic residence as a marker of solar ultraviolet B and
hence
vitamin D exposure. Here, we considered multiple
determinants of
vitamin D exposure (dietary and supplementary vitamin D,
skin
pigmentation, adiposity, geographic residence, and
leisure-time
physical activity-to estimate sunlight exposure) in relation
to
cancer risk in the Health Professionals Follow-Up Study.
Methods: Among 1095 men of this cohort, we quantified the
relation of
these six determinants to plasma 25-hydroxy-vitamin D
[25(OH)D] level
by use of a multiple linear regression model. We used
results from
the model to compute a predicted 25(OH)D level for each of
47 800 men
in the cohort based on these characteristics. We then
prospectively
examined this variable in relation to cancer risk with
multivariable
Cox proportional hazards models.
Results: From 1986 through January 31, 2000, we documented
4286
incident cancers (excluding organ-confined prostate cancer
and
nonmelanoma skin cancer) and 2025 deaths from cancer. From
multivariable models, an increment of 25 nmol/L in predicted
25(OH)D
level was associated with a 17% reduction in total cancer
incidence
(multivariable relative risk [RR] = 0.83, 95% confidence
interval
[CI] = 0.74 to 0.92), a 29% reduction in total cancer
mortality (RR =
0.71, 95% CI = 0.60 to 0.83), and a 45% reduction in
digestive-system
cancer mortality (RR = 0.55, 95% CI = 0.41 to 0.74). The
absolute
annual rate of total cancer was 758 per 100 000 men in the
bottom
decile of predicted 25(OH)D and 674 per 100 000 men for the
top
decile; these respective rates were 326 per 100 000 and 277
per 100
000 for total cancer mortality and 128 per 100 000 and 78
per 100 000
for digestive-system cancer mortality. Results: were similar
when we
controlled further for body mass index or physical activity
level.
Conclusions: Low levels of vitamin D may be associated with
increased
cancer incidence and mortality in men, particularly for
digestive-system cancers. The vitamin D supplementation
necessary to
achieve a 25(OH)D increment of 25 nmol/L may be at least
1500 IU/day.
4. <http://
dx.doi.org/10.1093/jnci/djj127>OPEN ACCESS:
EDITORIAL: Vitamin D Status and Cancer Incidence and
Mortality:
Something New Under the Sun
[<http://jncicancerspectrum.oupjournals.org/>Journal
of the National
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Sunlight generally is an effective means of generating large
amounts
of vitamin D, but it may not be safe for all persons. For
many
individuals, including those who are darkly pigmented or who
live at
northern latitudes, sunlight exposure may also be
insufficient to
generate adequate vitamin D. Conversely, vitamin D
supplements are
widely available, inexpensive, and believed to be safe over
a large
dosing range. As is often pointed out, the present
recommended
allowance for vitamin D-400 IU-for individuals aged 50-70
years is
inadequate even to maintain skeletal health and is probably
too low
for meaningful anticancer effects. A dose of 400 IU of
vitamin D3
will raise serum levels of 25(OH)D3 only modestly, by about
7 nmol/L
or less than 3 ng/mL. The use of this low dose, in
conjunction with
the relatively short duration of the trial, may explain the
recent
failure of vitamin D to reduce the incidence of colorectal
cancer in
the Women's Health Initiative.
In summary, a role for sunlight and vitamin D in cancer
prevention is
strongly suggested by epidemiologic observations, including
the
findings of Giovannucci et al., and potential mechanisms
have been
identified by experimental studies. The promising results
from both
observational and laboratory studies should usher in a new
era of
intervention studies of vitamin D and cancer risk. Because
many
public health scientists are already clamoring for higher
levels of
vitamin D supplementation for bone and other health,
randomized
trials of vitamin D and cancer risk should be undertaken
speedily. If
the promise of vitamin D holds, a brief walk in the sun may
turn out
to be a step toward cancer prevention.
[NOTE: For the full editorial, please follow the supplied
link.]
--
mailto:mwetzel mcn.org
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