Vitamin
D3
Essential for Good Health
and
How to Determine if You are Getting Enough and Using It
Charlie Skeen, C.N.C
Vitamin
D3’s Actions
Vitamin D3 is well known for its role for the growth and health
of the bone as it helps to regulate the absorption of calcium,
phosphorus, and magnesium. A deficiency will result in soft,
malformed bones unable to repair themselves, resulting in diseases
called rickets in children and osteomalacia in adults. However,
research for the last 10 years has shown that receptors for
vitamin D are present in a wide variety of cells, and has biologic
effects which extend far beyond control of mineral metabolism.
Besides its involvement in at least twenty other cell types,
vitamin D3 has the potential to reduce the risk of other diseases
such as breast, colon and prostate cancers, multiple sclerosis,
chronic fatigue, autism, diabetes, high blood pressure, heart
attacks and strokes, asthma, Alzheimer's disease and other forms
of dementia, muscle weakness due to aging, joint, low back and
muscle pain, osteo and rheumatoid arthritis, inflammation, and
regulation of neuromuscular and immune function. It is interesting
to note that people who live closer to the equator and who get
regular sufficient exposure to sunlight suffer less from these
diseases.
What
is Vitamin D3?
D3 is considered a vitamin since it is found in foods and can
be taken as a supplement. But, it also is what is called a prehormone
as it has no biological activity until the body converts it
into an active hormone. In this case, into 25-hydroxycholecalciferol
by the liver.
Process
of Hormonal Production
When sunlight hits the skin it absorbs ultraviolet (UVB) radiation
converting liver cholesterol molecules (ergosterol) under the
skin into 7-dehydrocholesterol, then into previtamin D3 and
continues until it becomes provitamin D3, or cholecalciferol.
It has been found in studies that when people with fair skin
are exposed to the summer sun for about 15 to 30 minutes wearing
just a bathing suit, the skin can manufacture anywhere between
10,000 to 50,000 units of cholecalciferol. Vitamin D researcher
Michael Holick, Phd. of Boston University School of Medicine
looked at the studies and determined the average amount produced
is around 20,000 units. This is far above the 200 I.U. recommended
by the Institute of Medicine of the National Academy of Sciences.
However, as a person's skin becomes more tan, wears sun block,
or has naturally darker skin, the skin produces less.
Note: While
20,000 I.U. is cited here other people have been known to manufacture
even higher amounts and maintain that level based on their exposure
to the sun. This would indicate that the mechanisms invloved
will of course vary due to the individual. What one's body may
produce and consider a safe level will naturally be different
for others.
Vitamin D3 in Supplements
Besides the production of vitamin D3 by the body we can also
take it in oral form as a supplement. The natural supplement
form of D3 is made from the wool of sheep which does not hurt
the animal.
The Skin Prevents Toxicity
In order to prevent toxic levels of cholecalciferol from building
up in the body the skin has the ability to degrade, or eliminate
it, when it reaches about 20,000 units, or whatever the individual's
body considers a safe level. This is accomplished with the same
ultraviolet light from the sun hitting the skin so that as you
make it above the saturation point you maintain a steady state
safe for that person, in this case around 20,000 units. Due
to this mechanism there has never been a reported case of vitamin
D toxicity due to exposure from the sun.
Toxicity
Can Occur When Taking Supplements of D
When taking supplements of vitamin D3 orally there is a risk
of reaching a level of toxicity. However, the amount needed
to become toxic would have to an extremely high amount over
a period of time. One of the scientists involved in vitamin
D3 research, Dr. Reinhold Vieth of the University of Tornoto
in Canada, indirectly asked the medical community in 1999 to
provide any evidence that 10,000 I.U. of D3 a day would be toxic.
He found that there was a lack of evidence that would support
statements about even moderate doses of vitamin D becoming toxic.
Dr. Vieth stated, "If there is published evidence of toxicity
in adults from an intake of 250 ug (10,000 IU) per day, and
that is verified by the 25(OH)D concentration, I have yet to
find it." In the Journal of Clinical Nutrition Dr. Vieth
asserts that toxic levels of D would occur after taking around
40,000 I.U. per day. That is the equivalent of 100 capsules
of 400 I.U. of vitamin D. When a person also combines heavy
sun exposure with excessive D supplementation there is increased
risk of toxicity, but Dr. Vieth is not aware of any cases being
reported. Vieth
R. Vitamin D supplementation, 25-hydroxyvitamin D concentration,
and safety. Am J Clin Nutr. 1999;69:842–56.
Case
of Overdose
I did find one case of a vitamin D overdose in a letter written
to Dr. Cannell, another research scientist on D, in April 2010.
In this letter the indivdual reported that he was taking 60,000
I.U. a day of D3 in a liquid, and occasionally took 180,000
I.U. for about eight months to try and help him get over a sinus
infection, and to prevent the cold and flu. This was in 2009.
Then he goes on to write that in November 2009 he started to
have symptoms of irregular heartbeats, nervousness, insomnia,
weight loss, difficulty concentrating, and muscle weakness.
After having blood work done by a physician he discovered his
D3 level was 406 nanograms per milliliter, about 4 times higher
than what is recommended, and his calcium level was excessvely
above the healthy range for his blood chemistry. After he stopped
taking vitamin D3 he says the physician didn't recommend anything
else except to recheck his blood levels of D3 and calcium in
a few months. He says he is 46 and has been in excellent health
all of his life with no serioius medical issues.
Dr. Cannell's reply to him was that he did overdose on vitamin
D3 reaching toxic levels, and he recommended that he stay out
of the sun until his calcidiol level was normal (50 to 80 nanograms
per milliliter), drink at least 8 eight-ounce glasses of water
daily to flush his kidneys and system, have a chemistry panel
periodically to make sure the kidneys were functionaing normally,
and to check the calcium level, although Dr. Cannell felt that
his calcium was no longer elevated. He also told him that there
probably was no permanent damage to any of his internal organs
because there were others who had higher levels of calcidiol
and they did not have any permanent damage to their internal
organs or kidneys.
Note:
I included this case because I wanted to empahsize that you
really have to take a lot of vitamin D3 over a period of time
for it to become toxic, and to point out the unfounded fear
of taking it in doses of anywhere between 2,000 to 10,000 I.U.
a day.
Hypersensitivity Mistaken for
Toxicity
When some people react adversly to vitamin D it is sometimes
mistaken as toxicity when in actuality it is hypersensitivity
syndromes due to excess calcium in the blood. This hypersensivity
can be due to several things such as hyperparathyroidism which
is excessive production of parathyroid hormone (PTH), parathormone,
by the parathyroid glands, and granulomatous diseases such as
sarcoidosis. Sarcoidosis is a disease of unknown cause that
leads to inflammation and can affect various organs in the body.
Normally, your immune system defends your body against foreign
or harmful substances. For example, it sends special cells to
protect organs that are in danger. These cells release chemicals
that recruit other cells to isolate and destroy the harmful
substance. Inflammation occurs during this process. Once the
harmful substance is destroyed, the cells and the inflammation
go away. In people who have sarcoidosis, the inflammation doesn't
go away. Instead, some of the immune system cells cluster to
form lumps called granulomas in various organs in your body.
Other things that
can contribute to this hypersensitivity is abnormal tissue in
the kidneys causing them to over-produce calcitriol which raises
the blood calcium level too high, and cancers, such as oat cell
carcinoma of the lung, and non-Hodgkin's lymphoma. Other health
problems can contrbute as well. When people have these health
problems they should not take vitamin D without the help of
a knowledgeable physician and periodic testing of their 25-hydroxycholecalcifero
(calcidiol) and calcium levels, as well as their PTH and 1,25-hydroxycholecalcifero
(calcitriol).
Natural
D3 Versus Plant Based and Synthetic D2
While D3 (cholecalciferol) is produced by the body and made
from sheep’s wool, D2 (ergocalciferol) comes from plants and
is made by the drug industry synthetically by irradiating yeast.
Synthetic D2 is often added to foods such as milk and can found
in supplements as well. While plants contain very little D2
and found to be harmless, the synthetic form of D2 can accumulate
in the body and has been known to produce severe health problems
such as malformed bone development, kidney damage and calcification
of tissues in the body such as hardening of the arteries. Research
over the years has demonstrated that it provides no benefits
in preventing or overcoming osteoporosis. The main form of D
used by the body is cholecalciferol, or D3. If you are presently
using supplements of D2, or foods fortified with it, it would
be wise to stop and obtain the natural form of D3.
The
Rest of the Story
Thus far we have learned that D3 can be obtained from sunlight
hitting the skin and taken as a supplement. However, this is
just the beginning as the body has to convert D3 (cholecalciferol)
into the biologically useful forms, calcidiol and calcitriol,
before it can be used.
Metabolism
of D3 into the Bioactive Forms
1st. Step - The Liver Produces
Calcidiol from Cholecalcifero (D3)
As D3 (cholecalciferol) enters the bloodstream, either produced
by the body from sunlight or as a supplement, it travels to
the liver where the enzyme D-25-hydroxylase (25-OHase) converts
it into 25-hydroxycholecalciferol, also known as calcidiol.
It then goes into the blood stream to be circulated throughout
the body. This hormonal form of vitamin D is five times more
potent than cholecalciferol. It's important that that we produce
adequate amounts of calcidiol as we shall see under the 2nd
and 3rd Step below.
2nd. Step - The Kidneys Produce
Calcitriol from Calcidiol
When calcium levels in the blood drop below a certain level,
around 9-11 mg per 100 milliliter of blood, this is picked up
by the parathyroid glands located on the posterior aspect, or
back, of the thyroid gland located in the neck. This causes
them to release a hormone called Parathyoid Hormone (PTH), or
parathormone, which tells the body to produce and secrete immune
system cells called cytokines which tell other cells called
osteoclasts to digest some of the bony matrix in the skeleton
and release ionic calcium and phosphate into the blood. This
also causes the kidneys to hold onto the calcium and decrease
retention of phosphate when forming urine. PTH also acts on
the kidneys to convert calcidiol by the enzyme 25-hydroxyvitamin
D3-1a-hydroxylase (1-OHase) into 1,25-hydroxycholecalciferol
[1,25-(OH)2D], also known as calcitriol. This hormonal form
is ten times more potent than cholecalciferol and is the most
potent form of vitamin D in the body. Calcitriol also enhances
the absorption of calcium from the food and supplements and
increases the ability of PTH to break down bone. When calcium
level becomes too high this is picked up by the cells in the
thyroid called parafollicular cells. These cells release a hormone
called calcitonin which decreases the activity of the osteoclasts
and activates other immune system cells, or cytokines, to tell
the osteoblasts to deposit calcium forming new bone tissue.
Calcitonin also increases the excretion of calcium through the
kidneys.
It is vital that the
homeostasis, or balance, of calcium be maintained in the blood
and extra cellular fluid that surround all of the cells at all
times. That's because calcium is required for numerous physiological
processes such as transmission of nerve impulses and release
of neurotransmitters, contraction of muscles, coagulation of
blood, gland secretions and cell division. Even just very small
changes in the level of calcium in the blood away from the homeostatic
range can produce severe neuromuscular problems ranging from
hyper excitability to the inability to function. Also, if the
calcium level became too high for long periods that could lead
to the buildup of calcium in the blood vessels, kidneys, and
other soft organs, interfering with their ability to function.
Vitamin
D3 Essential to Maintaining Healthy Bones and Blood Homeostasis
of Calcium
While the body takes calcium from the bones to maintain blood
homeostasis it also uses calcium from the food and supplements
we ingest. This process of breaking down and building bone is
an ongoing dynamic process throughout our lives, and when suffcient
calcium is ingested along with a healthy lifestyle and diet
which includes appropriate amounts of D3, calcidiol and calcitriol,
the bones will remain strong and healthy. However, if there
is an insufficent amount of calcium, or none is available, the
body will take it from the existing bone tissue to maintain
the homeostasis of the blood because without it the cells throughout
our body, such as the heart muscle and muscles of respiration,
or breathing, could not function and we would die. If this process
of contantly taking calcium from the bone to support blood homeostasis
occurs long enough it can result in osteopenia, and if left
unchecked into osteoporosis. The body will also be more susceptible
to illness and disease.
Conversion
by Other Tissue Cells
3rd.
Step - Other Tissue Cells Convert Calcidiol into Calcitriol
for Other Health Benefits
At one time it was thought that only the kidneys were involved
in converting calcidiol into calcitriol. However, scientists
have discovered that other tissue cells can make the conversion
as well. In fact, this has been the focus of much research for
the last ten years. While it has been understood for some time
that D3 being converted into calcidiol by the liver then into
calcitriol by the kidneys is important to maintain healthy calcium
status in the blood and for strong healthy bones, they have
discovered other far reaching implications of its postive effects
on other cells of the body such as cancer protection. In order
for this to take place though there must be an adequate amount
of calcidiol produced each day. If the body only produces enough
calcidiol for the kidneys to produce calcitriol to maintain
the calcium status in the blood and for healthy bones you will
not have enough left over for the other tissue cells in the
body to produce it. This will put your body at higher risks
for various cancers such as breast, prostate and colon, and
a whole host of other diseases such as osteoarthritis, muscle,
joint and low back pain, heart disease, Type 1 diabetes, and
auto immune diseases such as lupus, multiple sclerosis and rheumatoid
arthritis.
Many
People Are Deficient in Vitamin D
Based on studies by William B. Grant, Ph.D, one of the top vitamin
D researchers in the world, 80% to 90% of Americans are deficient
in vitamin D3. Another expert on vitamin D3, Dr. Michael Holick
of Boston University, states in his book, “The Vitamin D Solution”
(Hudson Street Press, 2010), that everyone should be above 30
nanograms per milliliter of 25-hydroxycholecalcifero (calcidiol)
which is the best indicator of a healthy level. In the third
National Health and Nutrition Examination Survey it was discovered
that in the United States Caucasians average only 18 to 22 nanograms
per milliliter, and African-Americans average 13 to 15 nanograms
per milliliter. Also, African-American women are 10 times as
likely to have levels at, or below, 15 nanograms per milliliter
as Causcasian women.
Less Sun Exposure Increases Health
Risks
Dr. Holick believes such low levels of 25-hydroxycholecalcifero
(calcidiol) could contribute to the high occurrences of several
of the chronic diseases in the United States. He points out
that in the Northeast United States the sun exposure is reduced
resulting in lower amounts of vitamin D being manufacturered
by the body. When compared to the South United States, where
there is greater sun exposure, cancer rates are lower. Dr. Holick
also points out that among dark-skinned Americans the amount
of prostate cancer, heart disease and high blood pressure are
higher than among whites.
Rise
of Type 1 Diabetes
Type 1 diabetes has been on the rise some time. Based on Dr.
Holick's observations this may be due in part to the fact parents
are protecting their children from exposure to the sun. He sights
a study done in Finland where 2,000 I.U's of vitamin D3 a day
were given to the infants. The results demonstrated an 88 percent
reduction in Type 1 diabetes.
The
Recommended Levels are Too Low, So How Much Vitamin D Do We
Need?
The current Recommended Dietary allowance for vitamin D3 as
established by the Institute of Medicine of the National Academy
of Sciences is:
0-50 year: 200 IU per day (including pregnant women)
50-70 years: 400 IU per day
> 70 years: 600 IU per day
These dosages listed
above are being challenged because extensive research for the
last 10 years reveals the fact that the levels of D3 listed
are not sufficient to bring the bioactive form of calcidiol
up to the healthy level, which is over 30 nanograms per milliliter
in the blood. Reserachers such as Dr. Holick, are recommending
a dosage of vitamin D3 daily of 1,000 to 2,000 I.U. for people
who do not receive suffcicent sun-light, women who are pregnant
and those who are are breast feeding, and people over 50 years
of age. As for infants who are being breast-fed the American
Academy of Pediatrics recommends they receive a daily supplement
of 400 units until they are weaned and are able to consume a
diet that includes at least 400 I.U. of vitamin D from food
sources.
Higher Dose Recommeded
While Dr. Holick recommends a level of clacidiol of over 30
nanograms per milliliter other scientists recommend a higher
amount with a optimal low and high range. The low range would
be around 50 nanograms per milliliter, or 125 nanomoles per
liter, and the high would be 80 nanograms per milliliter, or
200 nanomoles per liter. These are just conservative figures
that are considered safe. Each person will have determine how
much vitamin D3 they will require daily to produce these levels
of calcidiol due to different body sizes, metabolism, health,
nutrient precursers, and body fat. Since vitamin D3 is fat soluble
the more body fat you carry the more you will require because
it will become stored in the fat. Also, the extra blood vessels
to the fat will decrease, or water down, the vitamin D3.
Besides making sure
you are getting enough vitamin D daily you also want to avoid
taking too much to prevent toxicity. A toxic level can cause
such things as muscle cramps, artery and tissue hardening, calcified
bone, irritabilty and kidney and heart damage. But I have to
admit in all my years of dealing with people I haven't found
anyone who was getting too much vitamin D3. It has always been
the opposite, they were getting too little. As you read earlier
toxic levels wouldn't occur until you
took around 40,000 I.U. daily for several years.
Test
for Proper Levels of D
and Calcidiol
In order to really know if your body is receiving the correct
amount of D3 each day and is being converted into the bioavailable
form, calcidiol, you need to take a simple blood test. You can
go to your physician and request it, or you can click on the
link Vitamin
D, 25-Hydroxy (Calcidiol) and order it over the internet
without seeing a physician. When you go to take the test you
will find that it is done by a well known professional lab called
LabCorp Patient Service Center that has thousands of locations
throughout the United States and usually near your home. I have
checked around and found that their cost is very reasonable.
Test
for Calcitriol
Normally you would only have
to test for calcidiol. However, if you have, or had, kidney
problems and you wish to make sure you are producing adequate
amounts of calcitriol click on the link Vitamin
D, 1,25 Dihydroxy(Calcitriol) to take this test.
Ranges
to Check
When vitamin D3 levels are measured by a lab there are given
as either nanograms per milliliter, and nanomoles per liter.
The safe healthy ranges you are looking for are:
Low End: 50 nanograms per milliliter, or 125
nanomoles per liter
High End: 80 nanograms per milliliter, or 200
nanomoles per liter
You want your low end to be at least over 50 nanograms per milliliter,
or 125 nanomoles per liter to receive the benefits of vitamin
D3.
The lab test from
LabCorp Patient Service Center on the internet will be given
as nanograms per millilter. I gave both measurements in case
you go to a physician to have your test done and the lab used
gives the readings as nanomoles per litre. Also, make sure that
if you go to a physician to order your test that you tell him
to order the one for Vitamin D, 25-Hydroxy (Calcidiol),
and not Vitamin D, 1,25 Dihydroxy(Calcitriol).
Testing
Will Assist in You in Finding the Proper Amount of Vitamin D3
to Use
If you have been
taking vitamin D3 and take the blood test and find your calcidiol
level is too low then you need increase it. Conversely, if it
is too high then you need to reduce it. Although, many more
people will find that they are too low. Then test again to make
sure you are in the healthy range. Many people take vitamin
D3 in the range of 1,000 and to 2,000 I.U. daily but when tested
had to increase it even more as they were not producing enough
calcidiol. Some individuals had to increase their daily intake
to 5,000 and 10,000 I.U. You will not know if you have to increase
your intake or not until you have your blood tested. Once you
achieve a healthy blood level of calcidiol you should check
it once a year. Also, if you check it in the winter time and
you live in a part of the United States where you don't recieve
much sun, you need to check it again when you are exposed to
more sunlight in the spring and summer. Remember, as you expose
yourself to more sunlight you will require less as a supplement.
You will have to probably be taking higher amounts as a supplement
during the winter, such as 2,000 to 10,000 I.U., and less in
the months you are exposed to the sun, such as 1,000 to 2,000
I.U. And, for those who try to avoid the sun, once you find
your level of intake of vitamin D3 daily you will more than
likely have to maintain that dosage all year around, even if
you live in a sunny climate.
Sources
of Vitamin D3
Sunlight - ultraviolet (UVB) radiation
Food sources of vitamin D3: cold water fish
such as mackerel, salmon, sardines, herring, butter, egg yolks,
sweet potato, sunflower seeds, spinach, dandelion greens
Herbs: alfalfa, nettle parsley, eyebright,
fenugreek
Supplements: D3 in cod liver oil, fish oil
softgels, and tablets and capsules of varying strengths made
from the wool of sheep.
Things That Interfere with Vitamin D3,
Its Conversion, and Use In the Body
Liver and kidney disease
Weak liver and kidney function due to stress and poor diet
Excess Body Fat
Excessive alcohol consumption
Excessively Low fat diet
Excessively High fat diet
Processed fats and oils
Insufficient sunlight
Air Pollution
Chlorine in the
drinking water and bathing in it.
Alumium Fluoride in the drinking water and toothpaste
Flourescent lights
Sunscreens
Dark Skin
Aging
Smoking
Processed and refined foods such as white flour and rice, sugars,
processed fats and oils)
Fried Foods
Nutrient Deficiencies
Pharmaceutical
over-the-counter (OTC) and Prescription Drugs
Steroids
Laxatives such as Mineral Oil
“Bile acid sequestrants” like Questran
Sleeping Pills
Barbiturates like phenobarbital
Prednisone
Corstisone
Dilantin
Anticonvulsants
Bisphosphonates
such as Fosamax
Nutrients Required to Convert
Vitamin D3 into the Bioactive Forms
As can been seen from the list above there are many
things that interfere or prevent your body from absorbing, converting,
and using vitamin D3. However, its use and conversion is very
complex and depends upon other nutrients for its use. Some of
the major nutrients involved are magnesium, boron, zinc and
vitamin K2, which most people are deficient in as well. When
deficiencies occur it is very difficult for the body to convert
D3 into the useful biologically active forms no matter how much
D3 we ingest. So when you test for calcidiol levels and find
that you are not producing what you should, even though you
may be taking high amounts of D3, you need to examine not only
the things listed above that could prevent the conversion, but
also look at any possible companion nutrient deficiencies and
if found, correct them.
I hope this information has helped you to have a better understanding
of the importance of getting enough natural vitamin D3 daily,
and of how to assist the body in using it for improved health
and protection against disease for a better quality of life.
References
Laurlee Sherwood, Fundamentals of Physiology 2nd Edition, West
Publishing Company, 1995
Marieb, Elaine N., R.N., Ph.D., Human Anatomy and Physiology,
1992
Joseph B. Marion, Anti-Aging Manual - The Encyclopedia of Natural
Health, 1996
Michael T. Murray, N.D.,
Encyclopedia of Nutritional Supplements, 1996
Elson M. Hass, M.D., Staying Healthy with Nutrition - The Complete
Guide to Diet and Nutritional Medicine, 1992
Holick MF. “Vitamin D Deficiency,” New England Journal of Medicine
(July 19, 2007), Vol. 357, No. 3, pp. 266–80.
