Lay on the suncreen,
say docs |
Throw away that sunscreen, the
sun's healthy again. That's what your patients may think
after reading about a rash of new studies that find
vitamin D can prevent, well, everything under the sun.
Give them a word of caution.
Probably the most dramatic claim
is that a daily dose of 1100 IUs of vitamin D can bring
about a 60% reduction in incidence of common cancers
in postmenopausal women, from a US study in the June
American Journal of Clinical Nutrition. Research
in the May 28 Archives of Internal Medicine found
that higher vitamin D intake can lower breast cancer
risk in pre-menopausal women. Another study, in the
March issue of the Journal of Preventive Medicine,
reports a reduced incidence of colorectal cancer with
the daily intake of 1000-2000 IUs of vitamin D. Earlier
studies have shown vitamin D boosts the body's immune
response and reduces the risk of multiple sclerosis
in certain populations.
So you can see your patients are
faced with a real quandary: to slather or not to slather?
Of course it's not that simple. Here are a few vitamin
D sunshine facts to help temper your sun-loving patients'
enthusiasm.
MAD
DOGS AND ENGLISHMEN
Going out in the midday sun without protection is still
a definite no-no, says Dr Cheryl Rosen, the lead dermatologist
at Canada's National Sun Awareness Program. But patients
shouldn't worry about blocking all their vitamin D intake
from the sun. "Human use of sunscreen isn't perfect,"
says Dr Rosen. "People leave enough skin exposed, such
as the back of the hands or the face to maintain sufficient
vitamin D production in the skin."
Dr Michael Holick of the Vitamin
D Council and director of the Bone Health Care Clinic
at the Boston University Medical Center, agrees that
getting a little sun is fine. "We have evolved in such
a way as to promote adequate vitamin D production in
our skin, so going out in the sun is not unreasonable,"
he insists. "But you can't give a specific recommendation,
because it depends on the time of day and the season,
as well as skin pigmentation."
However, both he and Dr Rosen stress
that vitamin D's benefits don't negate skin cancer risk,
which is still significant. "Moderation is key," Dr
Holick reminds his patients. "If you're exposing your
arms and legs for 5 to 10 minutes, you're making 3000
to 5000 IUs of vitamin D — which is more than adequate
— so, put on protection if you're planning to stay
out in the sun longer," he adds.
GET
IN A SLATHER
"Broad spectrum sunscreen provides protection against
UVA and UVB rays," says Dr Rosen. An SPF of 15 is good
enough for most patients. A higher SPF is recommended
for those in need of stronger protection, though SPF
30 will only filter out about 4 to 5% more of the sun's
UVB rays than SPF 15.
A warning to your patients about
unhealthy tanning habits is also in order. Those seeking
a better tan with the help of tanning oils and lotions
are taking a big risk, according to Dr Holick. "There
is no lotion that really accelerates tanning. If you
put any kind of oil or lotion on your skin, you mat
down the top layer of dead cells which then acts as
a mirror and enhances penetration of UV radiation."
HOTBED
OF CONTROVERSY
Tanning bed enthusiasts hoping to combine a golden glow
with breast cancer prevention won't care for Dr Holick's
pearl of wisdom: "If you really want to use a tanning
bed to get your vitamin D, wear sunscreen on your face
and go for about 30 to 50% of the time recommended on
the machine. For example, if they say 15 minutes, go
for 5 to 7 minutes," he suggests. "Once a week is usually
fine, but it depends on the bed itself. The bottom line
is never to burn your skin," he insists.
Dr Rosen is less flexible on this
one: "Tanning beds increase the risk of skin cancer
and we don't need to add to the amount of UV radiation
we're already receiving," she stresses.
A
NEW LOW
In response to the new data, the Canadian Cancer Society
(CCS) is recommending a daily intake of 1000 IUs of
vitamin D, up from 200-400 IUs, for adults during the
fall and winter seasons. Canadians at risk of vitamin
D deficiency, such as people with darker skin, the elderly
and those who spend little time in the sun, should consider
taking the supplement year-round, the CCS says.
Supplements are the way to go in
order to get the full amount, Drs Holick and Rosen agree.
Your patients will be happy to know that they're cheap,
easy to find and have a very low risk of toxicity, even
at the higher doses.
Health Canada still hasn't finished
processing all this new input on the sunny vitamin.
On June 14 the agency announced that it's currently
evaluating the safety of vitamin D. The results of the
evaluation will determine if the current safety threshold
of 2000 IUs daily should change.
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