Every person needs sunlight exposure to create vitamin D, obesity impair

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Every person needs sunlight exposure to create vitamin D, obesity

impairs vitamin D absorption

JoAnn Guest

Apr 25, 2007 06:17 PDT

 

http://www.newstarget.com/003838.html

 

The following is part three of an eight-part interview with Dr.

Michael Holick, author of " The UV advantage " and one of the world's

most respected authorities on vitamin D and the health benefits of

natural sunlight. His work can be found at www.UVadvantage.com. Be

sure to print out the vitamin D myths, facts and statistics page

summarizing the key points of this interview.

---

Adams: It appears that we have a nation suffering from chronic

vitamin D deficiency, and that we are creating a whole new

generation of children

who are starting out deficient and are therefore at a high risk for

diseases like diabetes.

 

Dr. Holick: I think so, and that's why we're starting to sound the

alarm. I'll give you another statistic. The CDC reported that when

they looked across the United States at African American women

during their child-bearing years, aged 15-49 years of age, 42% were

vitamin D deficient at the end of the winter time.

 

Adams: So why isn't this front page news, why aren't Americans being

warned right now to go out and get more vitamin D into their bodies?

 

Dr. Holick: Part of the problem, I believe is that people just take

vitamin D for granted. And in fact I've talked to many

dermatologists who blithely will say on TV that you just drink

another glass of milk, or you get vitamin D from your diet. And

unfortunately it's incorrect.

 

They really are ignorant that very few foods naturally contain

vitamin D. And we're talking about oily fish like salmon and

mackerel, and you would have to eat salmon and mackerel 3-5 times a

week in order to get

your vitamin D requirement. Cod liver oil is good source, but

there are only 100 units in an 8 oz glass of vitamin D-fortified

orange juice.

 

So you would have to drink 10 glasses of orange juice a day. You

cannot get your vitamin D easily from your diet. And

even if you take a multivitamin, a multivitamin contains 400

international units of vitamin D, only 40% of what you need. So you

would have to make a conscious effort to take a multivitamin, drink

drink a glass or two of orange juice fortified with

vitamin D and eat salmon to get the amount of vitamin D that you

require to satisfy your body.

 

Adams: Or you could just walk outside and get natural sunlight on

your skin.

 

Dr. Holick: Or you can use sensible sun exposure, right. I mean, we

evolved in sunlight. We were bathed in sunlight, we feel better in

sunlight. And sunlight provides us with a gift, which is vitamin D.

And so, as you're well aware, in my book, I have tables at the end

of the book, where I tell people anywhere on the globe, any time of

the year, for any skin type at any time of day, how long they can

stay outside to get some safe sun to provide them with their vitamin

D requirements.

 

Adams: I think that's wonderful that you have that kind of chart in

your book, because that's what people are wondering. Can you give an

example, let's say someone of African descent living in the UK, for

example?

 

Dr. Holick: Sure. If you were living in the UK, say in July, they're

much further north than we are in the U.S., about 10 degrees further

north in latitude, so the sun's rays are even weaker, so they

probably

would need a good 30 to 60 minutes of exposure of arms and legs, or

hands face and arms, 2-3 times per week.

 

Adams: So that's several hours a week they need to be getting.

 

Dr. Holick: Yes. But for a Caucasian it would probably be no more

than 5

to 10 minutes.

 

Adams: Also 2 or 3 times per week?

 

Dr. Holick: Yes, so it makes a big difference. A typical African

American with very deep skin pigmentation -- they have sun

protection

that's typical of a sun protection factor of 15-30. And what that

means

is that they can stay out 15-30 times longer. Which means that they

need

to be out much longer to satisfy their body's requirements of

vitamin D.

 

 

Adams: Sure, that makes perfect sense.

 

Dr. Holick: And to give you an example of how powerful putting

sunscreen

on is, if you put a sunscreen on with an SPF of 8, it reduces your

ability to make vitamin D in your skin by more than 95%.

 

Adams: So you're pretty much shutting down vitamin D production with

even a mild sunscreen.

 

Dr. Holick: Exactly. And so what we recommend is you go outside for

5 or

10 minutes, enjoy the sun, make the vitamin D in your arms and legs

or

hands face and arms.

 

Adams: Right. That does sound sensible. Is there a direct

calculation

where you can say X number of minutes under the sun at this latitude

equals a certain number of units of vitamin D?

 

Dr. Holick: Within reason. The problem is that obviously there are

clouds in the sky, and there's pollution in the air including ozone

which absorbs the vitamin producing rays... but on average, I tell

my

doctor friends that if you're on the beach on Cape Cod, here in

Massachusetts in June, and you know that you're going to get a mild

pinkness to your skin, say 30 minutes of being outside, in a bathing

suit, it's equivalent to taking 20,000 units of vitamin D orally.

 

Adams: OK, so that's 20 times more than they might need.

 

Dr. Holick: Exactly. So what we recommend is that if you just expose

6-10% of your body, a couple of times a week, that's all you need.

 

Adams: Another question then. Can, in addition to sunburn which is a

totally separate issue, can a person's body actually produce too

much

vitamin D itself where it becomes toxic?

 

Dr. Holick: The answer is no. The body is very clever and no matter

how

much sun you're exposed to, you can never become intoxicated with

vitamin D. So if you're a sun-worshipper or a lifeguard, there's

never

been a reported case of vitamin D toxicity.

 

And the reason is, as we had shown many years ago, that when you're

exposed to sunlight, your body makes enough vitamin D, and that any

excess that's made is destroyed by the sun.

 

Adams: So it's a self-regulating system, and that's the best way to

go.

 

Dr. Holick: Exactly. And basically it tells you that Mother Nature

really had always programmed for you to get your vitamin D

requirements

from some sensible sun exposure.

 

Adams: What about storage of vitamin D in the body. If someone lives

in

a climate where it gets cloudy for 2 months in a row, what then?

 

Dr. Holick: Excellent point. Remember I told you about the major

circulating form of vitamin D which is 25-hydroxy vitamin D? It's

half-life in the blood stream is 2 weeks. So when you build up your

vitamin D levels during spring, summer and fall, you can use them

because your blood levels are much higher, and also some of the

vitamin

D is stored in your body fat and is released during the winter time.

But

the opposite is true also, and that is that if you're obese, we know

that most obese people are prone to deficiency in vitamin D, and the

reason is that the vitamin D gets sucked into the fat and it can't

get

out. And so we actually did a study in obese and non-obese

individuals,

and we gave them either an oral dose of vitamin D or we put them on

our

tanning beds so that they can make vitamin D in their skin. Obese

people

could only raise their blood levels of vitamin D about half as much

as

non-obese individuals.

 

Adams: Very interesting.

 

Dr. Holick: And so if a person is in fact overweight, they don't

need

1000 units of vitamin D a day, they probably need 2000 units of

vitamin

D a day.

 

Adams: That's fascinating, because again that plays into the

sensitivity

to vitamin D, so there's a vicious cycle going on there in obesity.

 

Dr. Holick: Exactly.

 

Adams: It's going to take a lot of vitamin D, a lot of sun exposure

to

help break that cycle. I've got another question for you here. So if

a

person has all the vitamin D that their body wants, and it's stored

in

the fat tissues, how long can they go, is it a period of months?

 

Dr. Holick: Yeah, I mean if you're getting a really adequate source

in

the spring, summer and fall, it'll last two to three months. So

it'll

get you through the winter. But for those that are concerned about

this

issue, what I always tell my patients is, take a multivitamin,

you're

getting 400 units and get some sun exposure to really make sure that

you're building up your stores of vitamin D. And then during the

wintertime especially take at least a multivitamin, and maybe take

an

additional supplement, a vitamin D supplement that contains another

400-1000 units of vitamin D.

 

 

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