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Vitamin D and Bone Health
Vitamin D plays an important role in
protecting your bones. Your body
requires vitamin D to absorb calcium.
Children need vitamin D to build strong
bones, and adults need it to keep bones
strong and healthy. When people do not
get enough vitamin D, they can lose
bone. Studies show that people with low
levels of vitamin D have lower bone
density or bone mass. They are also more
likely to break bones when they are
older.
Severe vitamin D deficiency is rare in
the United States. It can cause a
disease known as osteomalacia where the
bones become soft. In children, this is
known as rickets. This is a different
condition from osteoporosis.
NOF Recommendations for Vitamin D
The National Osteoporosis Foundation (NOF) recommends that adults under 50 get 400-800 International Units (IU) of vitamin D daily, and that adults 50 and over get 800-1,000 IU of vitamin D daily. Some people may need more. There are two types of vitamin D supplements. They are vitamin D3 and vitamin D2. Previous research suggested that vitamin D3 was a better choice than vitamin D2. However, more recent studies show that vitamin D3 and vitamin D2 are equally good for bone health. Vitamin D3 is also called cholecalciferol. Vitamin D2 is also called ergocalciferol.
Very high amounts of vitamin D can be
harmful and may result in kidney stones
and other kidney problems. Some kidney
problems can cause bone loss. Experts
disagree on the safe upper limit for
vitamin D. In the past, experts said
that people should not get more than
2,000 IU of vitamin D a day. Because of
recent studies, some experts now say
that a much higher amount is safe. It is
difficult to get too much vitamin D
unless a person is taking a prescription
dose of the vitamin. In that case,
healthcare providers can easily monitor
a person’s vitamin D level with a blood
test.
Sources of Vitamin D
There are three ways to get Vitamin D:
Sunlight
Food
Supplements and medications
Sunlight
Your skin makes vitamin D from the
ultra-violet light (UVB rays) in
sunlight. Your body is able to store the
vitamin and use it later. The amount of
vitamin D your skin makes depends on
time of day, season, latitude, skin
pigmentation and other factors.
Depending on where you live, vitamin D
production may decrease or be completely
absent during the winter. It is
difficult to measure the amount of
vitamin D that your skin makes.
People with fairer skin make more
vitamin D than people with darker skin.
People who live in higher latitudes such
as New York, instead of lower latitudes
such as Florida, may get less vitamin D
from sunlight. Window glass and air
pollution also decrease the amount of
vitamin D that your skin can make.
People who are housebound and do not get
outside in the sun are unable to make
vitamin D. As adults age, the ability to
make vitamin D decreases.
Because of concerns about skin cancer,
many people stay out of the sun, cover
up with clothing and use either
sunscreen or sunblock to protect their
skin. Probably the most important factor
which limits the ability of the skin to
make vitamin D is the use of sunscreen
and sunblock. Even an SPF (sun
protection factor) of 8 reduces the
production of vitamin D by 95 percent.
These products help protect the skin
from the harmful effects of the sun.
Because of the cancer risk from staying
in the sun, many people need to get
vitamin D from other sources.
Food
Vitamin D is naturally available in only
a few foods. It is very difficult to get
all the vitamin D you need from food.
Foods that have vitamin D include fatty
fish (examples are mackerel, salmon and
tuna), egg yolks and liver. Vitamin D is
also added to milk and to some brands of
orange juice, soymilk and cereals. At
this time vitamin D is not added to
other milk products like cheese, yogurt
and butter.
Supplements and Medications
Many people do not get enough vitamin D.
Therefore, they may need to take a
supplement. Before adding a supplement
with vitamin D, check whether your
calcium supplement, multivitamin or
medication contains vitamin D. Excluding
sunlight, the total vitamin D you get
includes the following: food +
supplements (including multivitamin) +
medications.
People Who May Not Get Enough Vitamin D
People most likely at risk for not
getting enough vitamin D include:
people who spend little time in the
sun
people with very dark skin
elderly people
people living in nursing homes or
other institutions
people with certain medical conditions
such as serious diseases of the nervous
or
digestive systems
obese or very overweight people.
Lab Test to Check Your Vitamin D Level
Some people ask how they can know if
they are getting enough vitamin D. The
best way to find out is with a simple
blood test that checks your vitamin D
level. Discuss with your healthcare
provider whether you should have this
test done. It measures 25-hydroxyvitamin
D, which is also written as 25(OH)D.
This test should not be confused with a
test for 1,25-dihydroxyvitamin D.
To protect your bone health, you need
one of the following test results
according to most experts:
75 nmol/L or higher
30 ng/mL or higher
If you have osteoporosis and your blood test shows that you do not have enough vitamin D, your healthcare provider may prescribe extra vitamin D (usually vitamin D2) until your blood level increases. Most healthcare providers do this for a short time to quickly boost the vitamin D level. Afterwards, you should continue on a vitamin D dose that maintains the blood level you need to protect your bones.
New members of the NOF Family receive our quarterly newsletter, Osteoporosis Report, and a copy of our newly revised, 100-page handbook, Boning Up on Osteoporosis. Renewing members receive NOF's quarterly newsletter.
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