youve seen the many recent headlines claiming that "sunlight
may prevent cancer," you probably wonder if the world isnt
going crazy. Sun exposure causes skin cancer, so how can this
be? There is indeed some research showing that a small amount
of sun exposure may reduce the risk of certain cancers, as well
as help keep bones strong. But you dont need to spend
lots of time in the sunand expose yourself to all the
known dangers of the sunto get the potential benefits.
D: not just for strong bones
have found that mortality rates for some cancersnotably
breast, colon, ovarian, and prostatetend to be lower in
sunnier regions. And some studies have found that people who
get little or no sun exposure tend to have higher rates of breast
and colon cancer. Why? Since sunlights ultraviolet-B radiation
is responsible for producing vitamin D in the body, researchers
have wondered if this could be the connection. There is some
laboratory evidence that vitamin D helps inhibit the growth
of some types of cancer cells and their spread. One study found
that women who have the lowest blood levels of this vitamin
have a higher risk of breast cancer than women with the highest
among vitamins, vitamin D is a hormone. It helps the body utilize
calcium and builds bones and teeth. You dont actually
need to consume vitamin D, provided you get a minimal amount
of sunlight. All it takes is about 10 to 15 minutes of sunlight
on your hands, face, and/or arms several times a week, depending
on your location, the time of year, the darkness of your skin,
and your age (see below). Most of us get that much sun without
even trying. And because D is a fat-soluble vitamin, most people
can store enough to supply them in the days, or even months,
when they dont get any sun.
who live in the northern third of the U.S. (for instance, Boston,
Detroit, or Chicago) can manufacture sufficient vitamin D from
a minimal amount of sun exposure from April through October.
Those in the center band (Washington, D.C., Kansas City, or
San Francisco) can manufacture the vitamin from March through
November. Farther south (Los Angeles, Dallas, or Atlanta), vitamin
D can be produced year round. Canadians have six months or more
of shorter, darker days when there isnt enough sunlight
to manufacture D.
you have dark skin, especially if you are African-American,
you may need longer exposure to sunlightperhaps up to
twice as much as a light-skinned personto produce the
same amount of vitamin D, since skin pigmentation screens sunlight
and reduces vitamin D production.
best D-fense for those over 60
you grow older, your ability to manufacture vitamin D declines,
and just increasing your sun exposure may not do the trick.
By the time you are 70, your vitamin D production is only 30%
of what it was when you were 25. Thats why the Recommended
Dietary Allowance for D is higher for older people: while those
under 50 need only 200 IU (international units) daily, those
50 to 70 should get 400 IU, and those over 70 need at least
a good idea to drink nonfat or low-fat milk for many reasons,
among them that milk is fortified with vitamin D. Each cup contains
100 IU. Other foods containing vitamin D are fatty fish such
as salmon and sardines, egg yolks, and fortified breakfast cereals.
(Yogurt and cheese are not made from fortified milk.)
over 70 should take supplemental vitamin D. So should people
in their sixties who dont get adequate amounts of vitamin
D from milk and other foods and also seldom get sun. Those at
highest risk are the homebound or institutionalized, as well
as those living in the northern third of the U.S. and in Canada.
Vegans and others who dont drink milk may also need a
supplement if they live up north.
are tricky, however, because overdoses of D can be toxic, leading
to kidney stones, kidney failure, muscle and bone weakness,
and other problems. Danger starts at 2,000 IU a day. Its
nearly impossible to get too much D from food. A daily multivitamin
with 400 IU of vitamin D is usually the best solution for those
over 60. Some calcium supplements also contain D.
note: Sunscreen can reduce or even shut down the synthesis
of vitamin D if you coat all exposed skin. This is a problem
chiefly for older people, who produce less D.
Reference Source 98