Vitamin D: What You Need to Know
Vitamin D
is necessary for normal bone mineralization and growth, maintenance of
muscle strength and coordination, cardiovascular health, and robust and
balanced immune function. Vitamin D is unique among vitamins working more like a hormone at the level of our DNA.
Vitamin
D has been estimated to regulate somewhere between 200-300 genes and
likely why vitamin D has been linked to so many health outcomes.
Summary
- Vitamin D promotes a healthy, balanced immune system through regulation and differentiation of immune system cells.
- Vitamin D supports the development and maintenance of bones and teeth by helping with the absorption and use of calcium.*
- Healthy Vitamin D levels play a key part of minimizing age-associated bone loss.
- You can absorb Vitamin D naturally through foods such as fatty fish,
egg yolks, and fortified cereals. Your body can also naturally absorb
Vitamin D through skin exposure to sunlight. The more skin you expose,
the more Vitamin D will be produced.
- Vitamin D deficiency is most directly related to poor bone health,
including rickets and osteomalacia. However, vitamin D deficiency is
also associated with an increased risk of other disorders, including
certain cancers, type I diabetes, multiple sclerosis, tuberculosis,
rheumatoid arthritis, muscle weakness and pain, depression,
hypertension, and pregnancy complications.
- In the U.S., only one-third are getting adequate amounts of Vitamin D
daily. USANA’s Vitamin D supplement is formulated with a high level of
vitamin D to help prevent deficiency by ensuring you get adequate
amounts throughout the entire year.
The Science of Vitamin D
Vitamin D promotes a healthy, balanced immune
system through its key role in regulation and differentiation of immune
system cells. It also has been linked to healthy endothelial function,
which is important for cardiovascular health. And, it also helps
maintain normal functioning of the nervous system.*
In addition, recent research has shown the following:
• Vitamin D may play a role in keeping our lungs healthy, with higher
concentrations of vitamin D resulting in positive effects on lung
function and health.*
• Vitamin D may play a role in helping elderly people maintain lean muscle mass.*
• Healthy vitamin D levels are a key part of minimizing age-associated bone loss.
Vitamin D supports the development and maintenance of bones and teeth by helping in the absorption and use of calcium.*
Calcium is the major structural element of bones and teeth. Your body
needs several nutrients in order for calcium to be absorbed and used
properly. Two of these nutrients are vitamin D and vitamin K. Vitamin D
increases absorption of calcium from the small intestine so the body
receives maximum benefit, while vitamin K helps make sure calcium builds
up in the bones and not in soft tissues. Adequate calcium and vitamin D
throughout life, as part of a well-balanced diet, may reduce the risk
of osteoporosis.
Natural Sources of Vitamin D
Food
There is a very small amount of vitamin D in a few foods, which makes
it almost impossible to get the levels you need from food alone.
However, some foods that include vitamin D are fatty fish, egg yolks,
orange juice, and some cereals.
Sun exposure
Every time we expose our bare skin to direct sunlight, we use
ultraviolet B (UVB) rays to produce vitamin D3 (cholecalciferol).
Sunlight can be a tricky thing, though, because too much can be a bad
thing. You need to monitor how much sun exposure is needed for healthy
vitamin D levels. The amount of vitamin D you actually absorb from
sunlight differs depending on the time of day and year, where you live,
and the color of your skin. The more skin you expose to the sun, the
more vitamin D is produced. So those winter rays don’t necessarily
produce the same amount of vitamin D that summer rays do.
There are two main factors that determine how much Vitamin D your body will produce when exposed to sunlight:
Time of Day and Year
During the fall and winter months, the sun is at an angle that causes
the atmosphere to lessen the amount of UVB rays that pass through. The
same process occurs during the early and later parts of each day.
You can test this simply by looking at the length of your shadow when
standing outside. If your shadow is longer than you are tall, not as
many UVB rays are reaching your body, so you’re not producing as much
vitamin D. This means that the closer to midday you are, the more UVB
rays your body is getting. Have you ever noticed that in the winter
months, your shadow is longer than you are for most of the day, but in
summer, it is much shorter during the midday hours?
Where You Live
Take a look at a globe and find the equator. The further away you are
from it means you are living in a location that makes it harder for
your body to use sunlight to make vitamin D. Once again, this is because
sunlight is hitting the atmosphere at more of an angle, blocking out
more UVB rays, especially during the winter season.
The Benefits of Vitamin D
Vitamin D status is a factor in the maintenance of good health.
However, reports continue to show that populations around the world are
suffering from vitamin D deficiency. In the U.S. alone, only one-third
are getting adequate amounts of vitamin D daily. The problem is
widespread and increasing, with potentially severe repercussions for
overall health.
Many cells in your body have vitamin D receptors and
need vitamin D to function properly, including those in your skin and
brain. USANA’s Vitamin D supplement is formulated with a high level of
vitamin D to help prevent deficiency by ensuring you get adequate
amounts throughout the entire year.
Vitamin D Deficiency
Deficiencies of vitamin D are common. It is currently estimated that
more than 1 billion people worldwide and 30-to-40% of the population
between 15 and 49 years of age in the United States suffer from vitamin D
deficiency. Because relatively small amounts of vitamin D are obtained
through the diet and so many lifestyle factors reduce endogenous
vitamin D synthesis, supplementation becomes an important avenue for
achieving and maintaining optimal vitamin D status.
Vitamin D deficiency is most directly related to poor bone health,
including rickets and osteomalacia. However, vitamin D deficiency is
also associated with an increased risk of other disorders, including
certain cancers, type I diabetes, multiple sclerosis, tuberculosis,
rheumatoid arthritis, muscle weakness and pain, depression,
hypertension, and pregnancy complications.
While many of these associations are actively being researched to
determine the extent of their connection with vitamin D deficiency, we
currently know that vitamin D unquestionably exerts a significant
influence on many body systems.
Signs and Risk Factors of Vitamin D Deficiency
Feeling Down and Out
Turns out, when you run low on vitamin D, it takes a pretty serious
toll on your mood. This is because our brains produce serotonin—a
hormone that affects our moods—at a higher rate when we’re exposed to
sunshine or bright light.
And as I mentioned, more exposure to sunlight
means more vitamin D.
Skin Color
Those with darker skin are at a higher risk for vitamin D deficiency
because skin pigment has a direct correlation with how much vitamin D is
absorbed. Some research suggests that those with darker skin may need
up to 10 times more sun exposure than those with lighter skin to produce
a comparable amount of vitamin D.
Age
Besides the fact that older people usually spend more time indoors,
aging correlates to vitamin D deficiency in a couple of ways.
First, the
skin loses its ability to absorb as much vitamin D as we get older. And
second, our kidneys slowly become less effective at converting vitamin D
into the form used by our bodies.
Sweat
Excessive sweating (specifically, on your forehead) is a very common
symptom of those facing vitamin D deficiency. So if you’re constantly
wiping the sweat off your brow (outside of the gym), you might want to
look into getting a blood test done to check your levels.
Achy Bones
Many people who are unknowingly deficient in vitamin D will complain
of bones and joints that are achy or painful.
This is because vitamin D
is very important for maintaining strong bones. Calcium and phosphorus
are essential for developing a healthy structure and strength of your
bones, and you need vitamin D to absorb these minerals.
Excessive Weight
Vitamin D is fat-soluble—meaning that the fat in our bodies is how we
collect and store it. So if you’re overweight, the excessive amount of
fat in your body needs a comparable amount of vitamin D to absorb. So
you’ll need a lot more vitamin D than someone with a lower percentage of
body fat.
Gut Problems
Vitamin D is a fat-soluble vitamin. So certain gut conditions that
cause a lower absorption of fat can also lower your absorption of
vitamin D.
How Much Vitamin D Do You Need?
It varies depending on where you look, but here is a chart of the
recommended daily intakes from various organizations, brought to you by
the
Vitamin D Council.
VITAMIN D – IU TO MICROGRAM CONVERSION
1 microgram vitamin D = 40 IU vitamin D
e.g. 400 IU vitamin D = 10 mcg vitamin D
How Safe is Vitamin D?
Although vitamin D can be toxic in very large doses, toxicity is
rarely the biggest cause for anxiety. Instead, deficiency has become
relatively common. Vitamin D deficiency has been correlated to a number
of health concerns.
Because of the prevalence of deficiency, in the most recent revision
of the Dietary Reference Intakes (DRI), the recommended dietary intake
for certain age groups was increased as much as 50 percent. The
tolerable upper intake level (UL) for vitamin D in adults is 100 mcg
(4000 IU) per day.
There are no published accounts of vitamin D toxicity occurring as a
result of sun exposure. Research also suggests that vitamin D toxicity
is very unlikely at dietary intake levels below 1,000 mcg (40,000 IU)
per day in healthy adults.
Vitamin D supplements do have the potential to interact with certain
types of medications (including steroids and cholesterol-lowering
drugs). Those taking medications should discuss vitamin D
supplementation with their healthcare providers prior to use.
Talk to your doctor about healthy vitamin D levels, and ask for a test to find out if you are deficient.
The USANA Difference
USANA’s Vitamin D supplement is made with cholecalciferol (vitamin
D3), which research suggests is better than competing forms at raising
levels of vitamin D in the blood.
A clinical study conducted by USANA
scientists showed individuals taking USANA products are six times more
likely to have vitamin D levels in the optimal range.*
Even when the winter months are behind us, it doesn’t mean your body
needs less of a good thing. USANA’s Vitamin D supplement is a safe and
easy way to get 2,000 IU of maximum-strength vitamin D enhanced with 30
μg of vitamin K.*
Frequently Asked Questions
Additional Resources
Vitamin D Deficiency: The Truth Revealed
The ABCs of Vitamin D
Scientifically Speaking: Got Vitamin D?
Uncovering the Benefits of Vitamin D
Vitamin D is a Supplement for All Seasons
| *These statements have not been evaluated by the
Food and Drug Administration. This product is not intended to diagnose,
treat, cure, or prevent any disease. |
References
- Vitamin D Council. https://www.vitamindcouncil.org/about-vitamin-d/how-do-i-get-the-vitamin-d-my-body-needs/
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Pregnant Women Residing in the Northern United States and Their
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- DeLuca HF. Overview of general physiologic features and functions of vitamin D. 2004. Am J Clin Nutr 80(6 Suppl):1689S-1696S.
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women. 2003. Am J Clin Nutr 77(2):504-511.
- Holick MF. Vitamin D: importance in the prevention of cancers, type 1
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79(3):362-371.
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supplementation and the risk of fractures. 2006. N Engl J Med
354(7):669- 683.
- Jumar J, Muntner P, Kaskel FJ, Hailpern SM, Melamed ML. Prevalence
and Associations of 25-Hydroxyvitamin D Deficiency in US Children:
NHANES 2001-2004. 2009. Pediatrics 124:e362-e370.
- Looker AC, Pfeiffer CM, Lacher DA, Schleicher RL, Picciano MF,
Yetley EA. Serum 25-hydroxyvitamin D status of the US population: 1988-
1994 compared with 2000-2004. 2008. AJCN 88(6):1519-1527.
- Papadimitropoulos E, Wells G, Shea B, Gillespie W, Weaver B, Zytaruk
N, Cranney A, Adachi J, Tugwell P, Josse R, Greenwood C, Guyatt G.
Meta-analyses of therapies for postmenopausal osteoporosis. VIII:
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osteoporosis in postmenopausal women. 2002. Endocr Rev 23(4):560-9.
- Saintonge S, Bang H, Gerber LM. Implications of a New Definition of
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