Guide to Wellness – July 2019

Let the Sunshine In

18 GUIDE TO WELLNESS CR.ORG

As the evidence that some

sun is good for you grows,

many experts are rethinking

their staunch sun-avoidance

advice. For example, despite

Australia having one of the

highest skin cancer rates in

the world, Cancer Council

Australia recognizes that

some time in the sun without

sun screen or other protec-

tion is important, according

to Robyn Lucas, Ph.D., a

professor at the Australian

National University College

of Health and Medicine who

researches environmental

effects on health. And recently

the National Academy of

Sciences assembled an inter-

national group of medical

experts from different fields

to discuss sun safety. The

report from that meeting,

published in late 2017 in

JAMA Dermatology, stated

that “although the harms

associated with overexpo-

sure outweigh the benefits,

the beneficial effects of

UVR [ultraviolet radiation]

exposure should not be

ignored in developing new

sun safety guidelines.”

Bone Health and Beyond

Sun exposure’s best-known

benefit is vitamin D synthe-

sis, which occurs in the skin

in response to the sun’s UVB

rays. Vitamin D is a critical

nutrient: “It’s absolutely

essential to promote absorp-

tion of calcium, the min-

eral that helps keep bones

strong,” says Clifford Rosen,

M.D., an osteoporosis

researcher at the Maine

Medical Center Research

Institute in Scarborough.

And sunlight may also play

other roles in promoting

good health. The research is

ongoing, but so far studies

suggest that UV exposure

might lower blood pressure

(which helps to protect against

heart attack and stroke), curb

appetite, and reduce the risk

of obesity, type 2 diabetes,

and possibly certain autoim-

mune diseases.

Sunshine might even be

linked to longevity: A Journal

of Internal Medicine study

that monitored nearly 30,000

Swedish women for about

20 years found that those who

spent more time in the sun

The UVB

rays that

help our skin

produce

vitamin D

are also the

same type

that causes

sunburn—a

major risk

factor for

skin cancer.

skin absorbs, but it’s way less

than you need to get a sun-

burn,” Lucas says.

To determine the length

of time you can stay in the

sun without burning, Lucas

suggests using the UV Index—

which forecasts the level

of solar radiation in your

area on a scale of 0 to 11. The

UV Index varies by location

and time of day and year;

to find the UV Index for any

particular day and time in

the U.S., enter the ZIP code

of the area you’re in on the

Environmental Protection

Agency’s web page, at

epa.gov/su nsa fet y/uv-index-1.

To calculate the right UV

dose for you, divide 60 (as

in the number of minutes

in an hour) by the UV Index

to find out how many minutes

outdoors it will take for you

to get 1 SED. SED stands for

“standard erythemal dose,”

a fixed dose of sun intensity

that will cause erythema, or

reddening of the skin. (See

“Don’t Get Burned,” at left,

for the approximate SED it

takes for different skin types

to burn.) For example, if the

UV Index is 7, divide 60 by

7 to get 8 minutes for 1 SED.

If you are fair, you’ll get sun-

burned with 2 to 3 SED (16 to

24 minutes).

“These numbers are a gen-

eralization of skin type by

ethnicity,” Lucas says.

So it is best to be conserva-

tive using them. In the above

example, for instance, to

be on the safe side you might

go in the sun unprotected

lived six months to two years

longer than those who racked

up less sun exposure. “More

research is required to repli-

cate this work, but if it’s a real

effect, it’s very important,”

Lucas says.

But the UVB rays that

help our skin produce vita-

min D are also the same

type that causes sunburn —a

major risk factor for skin

cancer. That’s why it is key

to find the right balance.

Short Stints Do

the Trick

According to Rosen, in the

summer it takes only about

10 minutes a day of unpro-

tected solar exposure on a

small area of skin to produce

around 5,000 IU of vitamin

D, which is enough for most

people—even older folks, who

have a slightly reduced

capacity to make vitamin D—to

maintain normal blood levels.

But for some people,

10 minutes might be too

long; for others, too short.

“How much is enough is hard

to quantify since skin pig-

mentation affects how

much UV radiation your

Skin Type

SED

Needed

for Skin

to Burn

Very Fair 1-2

Fair 2-3

Olive 4-5

Moderate Brown 5-6

Dark Brown or Black 7-8

Getting a sunburn is

possibly the single most

dangerous thing you can

do to your skin. When

it comes to how much

sun you can get without

burning, let your skin type

be your guide.

DON’T GET

BURNED