Obesity Impairs Vitamin D Absorption

[Guest guest]

Every person needs sunlight exposure to create vitamin D,

obesity impairs vitamin D absorption

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 another good source,

although milk or orange juice fortified with vitamin D has some, but

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

and orange juice. So you would have to drink 10 glasses of milk or 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 2

glasses of milk, 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, and

then to use sun protection thereafter.

 

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, and then put the sunscreen on.

 

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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