What Is Vitamin D?
often called the “sunshine vitamin,” is an important nutrient. Its active form,
called calcitriol, behaves like a hormone in the body. The body can produce
10,000 IU or more of vitamin D with as little as 10 to 15 minutes of exposure
to summer sunlight.
plays a crucial role in supporting and maintaining bone health. There are few
natural food sources that contain vitamin D. Food manufacturers began
fortifying milk and other products with vitamin D decades ago, aiming to wipe
out rickets, a childhood bone disease.
for this important hormone are found in virtually every type of cell and tissue
in the body. Receptors work like locks: The lock turns when the right key is
inserted, prompting the cell to act in a certain way. Evidence shows that
people with higher levels of vitamin D may live longer.
Studies also suggest that a majority of
Americans have insufficient or deficient levels of vitamin D.
Why Do You Need Vitamin D?
of vitamin D receptors throughout the body hints at the importance of the
vitamin. Research shows that vitamin D plays a crucial role in the health of
the immune system, brain, heart, and blood vessels, among other organs and
now monitor their patient’s vitamin D levels and prescribe supplemental vitamin
D when levels are too low. A lack of vitamin D may increase your risk of
developing numerous diseases and conditions.
diseases — such as type 1 diabetes, multiple sclerosis, and rheumatoid
arthritis —may be linked to a vitamin D deficiency. Autoimmune diseases occur
when the immune system attacks the body’s own tissues. Too little vitamin D has
been linked to poor immune system function.
deficiency is also linked to a risk for type 2 diabetes, osteoporosis (a
condition that results in brittle bones), heart disease, mood disorders, and
even certain types of cancer. This is because the active form of vitamin D
helps control chronic inflammation. Ongoing inflammation has been linked to
diseases such as hardening of the arteries (atherosclerosis), arthritis
(painful, inflamed joints), and even cancer.
may be taken as a supplement. Two forms are available: vitamin D-3 and vitamin
D-2. Vitamin D-3 is preferable, as it is better absorbed when taken by mouth.
government recommended dietary intakes for vitamin D range from 400 IU
to 800 IU depending on your age, but are based on the needs of healthy
individuals, not someone who may already be deficient or battling an illness or
disease. Many experts argue that higher daily intakes above what’s recommended,
even what may be considered megadosing (up to 50,000 IU per week), are required
to achieve better health outcomes.
Vitamin D Deficiency
following factors can affect your vitamin D levels:
use of sunscreens
dark skin don’t make vitamin D as easily as light-skinned people when exposed
dissolves in fat, and is stored in fat cells. Overweight people tend to have
more vitamin D stored in fat rather than circulating in the blood. They may
require higher doses of vitamin D-3 to maintain optimal serum levels.
Vitamin D Toxicity
toxicity, resulting from taking too much supplemental vitamin D, is relatively
rare. The amount of supplemental vitamin D needed to cause vitamin D toxicity
is more than 10,000 IU per day, taken every day for months. The tolerable upper
intake levels published by the U.S. government range from 1,000 IU per day for
infants, to 4,000 IU per day for children over 9 years old and adults.