Vitamin D article in Dec 2003 Nutrition Action Healthletter

[Guest guest]

Excellent Vitamin D article:

Here are some excerpts from an article called " Soaking Up The D's, "

in the December 2003 issue of Nutrition Action Healthletter.

The people from the Center For Science In The Public Interest (CSPI)

interviewed F. Holick, director of the Vitamin D, Skin and

Bone Research Laboratory and Professor of Medicine, Dermatology,

Physiology and Biophysics at Boston University Medical Center. Dr.

Holick's book, The UV Advantage, will be published by iBooks and

distributed by Simon and Schuster in May.

Many people get too little Vit D, because few foods contain it, and

most people do not get enough sun exposure to make enough.

The skin makes Vit D when UVB penetrates the skin and converts a

precursor into Vit D.

If you live north of Los Angeles on the West Coast or Atlanta in the

East, you won't get enough UVB in the winter to make enough Vit D.

Vit D deficiency increases the risk of bone fracture. Vit D

increases the efficiency of the intestines to absorb calcium and

phosphorus from food, and increases the activity of bone cells that

make and lay down bone matrix.

If an adult is deficient in Vit D and not getting enough calcium,

calcium is drawn out of the bones (to keep your heart beating and

muscles contracting), which causes osteoporosis.

Research shows that by giving nursing home residents 800 IU of Vit D

and 800 mg of calcium a day, they markedly reduce the risk of

fractures.

If you are deficient in Vit D, you only absorb 10-15% of the calcium

you consume.

Vit D deficiency may cause other problems: almost every tissue in

the body, including the brain, breasts, bone, colon, intestine,

heart, kidneys and prostate—has a receptor for Vit D. The active

form of Vit D is one of the most potent hormones to inhibit cell

proliferation. If a cancer cell is proliferating out of control,

activated Vit D could inhibit its growth.

If you use a sunscreen rated SPF-8 properly, it reduces the ability

to make Vit D by more than 90%.

Sensible sun exposure would be 5-10 minutes on the arms and legs or

face and arms, two to three times a week. Your skin makes the most

Vit D between 11 a.m. and 2 p.m. Five to ten minutes is for a light-

skinned Caucasian in Boston in June, between 11-2 p.m. In Florida,

it may be only two to three minutes. In Boston, you wouldn't make

any Vit D at 8 a.m., even if it's a sunny summer day.

North of 35 degrees latitude you cannot make any vitamin D in the

winter, even at noon. Canadians cannot make Vit D in their skin for

four to seven months of the year.

You need 1,000 IU per day of Vit D if you are not exposed to the

sunlight.

If you are 70 years old, your skin can make only 25% of the Vit D

that a 20-year-old can make when exposed to the same amount of sun.

But a 70-year-old can make enough. If elders are out in the sunlight

for 15-20 minutes a couple times a week, they will maintain their Vit

D levels.

The National Academy of Sciences says that people should not exceed

2,000 IU of Vit D per day, the upper safe limit. This was determined

from published studies. However, other studies suggest that at least

5,000 IU and maybe 10,000 IU a day is safe.

You cannot get Vit D toxicity due to too much sun---any excess from

the sun is destroyed.

If you consume too much Vit D from supplements or food, you absorb

too much calcium, so you can get high blood calcium, kidney stones,

kidney calcification, kidney failure, soft-tissue calcification, and

calcification of blood vessels that can lead to death.

People who are deficient in Vit D can be given 50,000 IU once a week

for eight weeks to replete their stores of Vit D, and then 50,000 IU

once or twice a month. Dr. Holick has never seen any Vit D toxicity

with this regimen.

People should get their Vitamin D levels checked at least once a

year. The best time is around November, because if you are deficient

then, you will be severely deficient at the end of winter. The test

to order is 25-hydroxy-vitamin D, NOT 1,25-dihydroxy-vitamin D, which

is the active form; testing the active form is useless. Blood levels

of

25-hydroxyvitamin D should be between 30 and 50 nanograms per

milliliter.

You store Vit D in your body fat. If you get enough sun in the

summer and fall, your stores will carry you through the winter.

Bob Bessen

[Guest guest]

ABSOLUTELY fascinating. I wonder if this is the link explaining the

well established observation that colon cancer is more prevalent at

northern latitudes than it is futher south. For example, it is

noticeably more common in northern US states than it is in the south.

Rodney.

> Excellent Vitamin D article: ..............................

>

> ........ North of 35 degrees latitude you cannot make any vitamin

D in the

> winter, even at noon. Canadians cannot make Vit D in their skin

for

> four to seven months of the year.

>

> You need 1,000 IU per day of Vit D if you are not exposed to the

> sunlight.

>

> If you are 70 years old, your skin can make only 25% of the Vit D

> that a 20-year-old can make when exposed to the same amount of

sun.

> But a 70-year-old can make enough. If elders are out in the

sunlight

> for 15-20 minutes a couple times a week, they will maintain their

Vit

> D levels.