This is from today's Wall Street Journal's "Health Mailbox." David

 

Health Mailbox

Columnist Melinda Beck answers readers' questions
July 29, 2008; Page D2

Q: Is there a safe period of time to sit in the sun to get sufficient vitamin D -- but not risk skin cancer?

A: You'll get different answers depending on
who you ask. The nonprofit Vitamin D Council says that 15 to 20 minutes
of noonday sun exposure, twice a week, will give most fair-skinned
people in most of the continental U.S. sufficient D. "You are more
likely to get skin cancer -- most of which are benign -- if you sit in
the sun, but studies are showing that you're more likely to die of
other kinds of cancer if you don't get adequate vitamin D," says John
Cannell, the group's founder.

The American Cancer Society advises people not to
deliberately sunbathe, and to use the "Slip, Slap, Slop" approach --
slip on a shirt, slap on a hat and slop on the sunscreen -- if they are
going in the sun. Cancer experts also recommend getting vitamin D
through supplements and not through sunshine -- especially if you are
very fair skinned or have any precancerous spots.

The bottom line is that more study is needed to fully
understand the role of vitamin D in health, what the right level is and
the best way to obtain it.

Q: If I decide to get 20 minutes of sunlight
a day, does it need to be in one "sitting" or can you accumulate enough
by being in the sun, off and on during the day?

A: Those 20 minutes can be intermittent -- "but
it must be when the sun is high enough in the sky so that your shadow
is shorter than you are," says the Vitamin D Council's Dr. Cannell.

Q: I'm fair-skinned in the depths of winter,
but I tan very easily and am darkish by early spring. Does this mean
that I should spend more time in the sun for my vitamin D?

A: If you are well tanned all over your body your vitamin D stores are fine, says Dr. Cannell.