If you shun the sun, suffer from milk allergies, or adhere to a strict vegetarian diet, you may be at
risk for vitamin D deficiency. Known as
the sunshine vitamin, vitamin D is produced by
the body in response to sunlight. It is also occurs naturally in a few foods --
including some fish, fish liver oils, and egg yolks -- and in fortified dairy
and grain products.
Vitamin D is essential for strong bones because it
helps the body use calcium from the diet. Traditionally, vitamin D deficiency has been
associated with rickets, a disease in which the
bone tissue doesn't properly mineralize, leading to soft bones and skeletal
deformities. But increasingly, research is revealing the importance of vitamin
D in protecting against a host of health problems.
Symptoms and Health Risks of Vitamin D Deficiency
Symptoms of bone pain and muscle weakness
can mean you have a vitamin D deficiency. However, for many people, the
symptoms are subtle. Yet even without symptoms, too little vitamin D can pose
health risks.
Low blood levels of the vitamin have been associated
with the following:
·
Increased risk of
death from cardiovascular disease
·
Cognitive
impairment in older adults
·
Cancer
Research suggests that vitamin D could play a role in
the prevention and treatment of a number of different conditions, including
type 1 and type 2 diabetes, hypertension, glucose
intolerance, and multiple sclerosis.
Causes of Vitamin D Deficiency
Vitamin D deficiency can occur for a number of
reasons:
1.
You don't
consume the recommended levels of the vitamin over time. This is likely if you follow a strict vegetarian
diet, because most of the natural sources are animal-based, including fish and
fish oils, egg yolks, cheese, fortified milk, and beef liver.
2.
Your
exposure to sunlight is limited. Because
the body makes vitamin D when your skin is exposed to sunlight, you may be at risk of
deficiency if you are homebound, live in northern latitudes, wear long robes or
head coverings for religious reasons, or have an occupation that prevents sun
exposure.
3.
You have
dark skin. The pigment melanin
reduces the skin's ability to make vitamin D in response to sunlight exposure.
Some studies show that older adults with darker skin are at high risk of
vitamin D deficiency.
4.
Your kidneys cannot
convert vitamin D to its active form. As
people age their kidneys are less able to convert vitamin D to its active form,
thus increasing their risk of vitamin D deficiency.
5.
Your
digestive tract cannot adequately absorb vitamin D. Certain medical problems, including Crohn's disease, cystic fibrosis, and celiac disease, can affect
your intestine's ability to absorb vitamin D from the food you eat.
6.
You
are obese. Vitamin D is extracted from the blood by fat
cells, altering its release into the circulation. People with a body mass index of 30 or greater often have low blood levels of
vitamin D.
Tests for Vitamin D Deficiency
The most accurate way to measure how much vitamin D is
in your body is the 25-hydroxy vitamin D blood test. A level of 20
nanograms/milliliter to 50 ng/mL is considered adequate for healthy people. A
level less than 12 ng/mL indicates vitamin D deficiency.
Treatment for Vitamin D Deficiency
Treatment for vitamin D deficiency involves getting
more vitamin D -- through diet and supplements. Although there is no consensus
on vitamin D levels required for optimal health -- and it likely differs
depending on age and health conditions -- a concentration of less than 20
nanograms per milliliter is generally considered inadequate, requiring
treatment.
Guidelines from the Institute of Medicine increased
the recommended dietary allowance (RDA) of vitamin D to 600 international units
(IU) for everyone aged 1-70, and raised it to 800 IU for adults older than 70
to optimize bone health. The safe upper limit was also raised to 4,000 IUs.
If you don't spend much time in the sun or always are
careful to cover your skin (sunscreen inhibits vitamin D production), you
should speak to your doctor about taking a vitamin D supplement, particularly
if you have risk factors for vitamin D deficiency.
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