Vitamin D
The only vitamin body
makes on its own
Can also be gained from
sun exposure, is vital for
your blood and bones
Vitamin D, not an unfamiliar name for the Indian masses subjected to numerous advertisements on
health drinks and dietary supplements fostering strong teeth and bones every other minute on
television channels or radios; available for people of all ages, be it a toddler, working man or
woman; or the elderly. For strong and healthy teeth and bones one requires calcium, an essential
mineral for maintaining the health of our nerves, muscles and internal organs like heart. Inadequate
calcium intake can lead to low bone mass increasing the risk of metabolic bone diseases and high
fracture rates with increasing age. Calcium acquired from foods or supplements doesn't get absorbed
on its own in our body without the presence of this essential fat-soluble nutrient - Vitamin D,
particularly vital for its absorption and homeostasis. It was only in 1922, when American researcher
Elmer McCollum tested modified cod liver oil to cure rickets affected dogs, thus discovering the
factor present in it as the fourth vitamin to be named Vitamin D.
What is it Vitamin D?
Traditionally known as anti-ricket factor or sunshine
factor, Vitamin D is a steroid, a group of fat-soluble
prohormones synthesized by the body and functions as
a hormone. The two most important forms in which
vitamin D can be found are:
Vitamin D2 (ergocalciferol)
Activated ergosterol, the vitamin D of plant origin.
It arises from ultraviolet irradiation of ergosterol.
It occurs naturally in some fungi & some fish oils.
vitamin D3 (cholecalciferol)
Synthesized in the skin on irradiation of
7dehydrocholesterol
It is activated when metabolized to
1,25dihydroxycholecalciferol
It is the vitamin D of animal origin found in the skin,
fur and feathers of animals and birds exposed to
sunlight and also in butter, fish oils and egg yolk.
Vitamin D required by our body primarily
is Vitamin D3.
Major vitamin D types and mechanism of activation
Vitamin D exists in several forms viz. D1, D2, D3, D4 and D5 wherein the only important form for
humans is vitamin D3 (Cholecalciferol) and can be readily obtained from sunlight and dietary
sources. Many fortified food products contain vitamin D2 (Ergocalciferol) which unlike vitamin
D3, is not produced naturally upon sunlight exposure. Vitamin D binding protein (DBP) aids in
their transportation via bloodstream to liver, kidneys and other organs for further hydroxylation
processes required for their activation.
When either, vitamin D3 or vitamin D2 binds to DBP, it
is carried to liver where it is transformed to prohormone Vitamin D (Calcidiol), a
primary circulating form of vitamin D. The second hydroxylation process takes place in several
extrarenal tissues, not exclusive to the kidneys, where calcidiol transforms into its biologically
active form, 1,25-dihydroxyvitamin D (Calcitriol). Calcitriol released in blood binds to DBP and
reaches the target tissues to perform signaling mechanisms through vitamin D receptors present
on various cells and tissues all over the body. Both these types of vitamin D cure rickets effectively
but Vitamin D is known to be much more potent to maintain serum
concentrations of 25-hydroxyvitamin D than vitamin D2 because of its higher affinity towards
DBP, thus resulting in a shorter circulating half-life and duration of action of 25-hydroxy D2 as
compared to 25-hydroxy
Vitamin D: Vital for our survival
Vitamin D is primarily known to promote intestinal calcium absorption and maintain adequate
serum calcium and phosphate concentrations for normal mineralisation of bone, bone growth
as well as bone remodeling by osteoclasts and osteoblasts. Calcitriol, a steroid hormone is
crucial for maintaining calcium homeostasis and triggers the release of parathyroid hormone
(PTH) when serum calcium test levels fall below 8.8 mg/dL. PTH prompts kidneys to increase
calcitriol production, stimulating an increased intestinal absorption of calcium for bone remodeling.
Production of calcitriol is reduced when calcium and phosphorus genes signala normal bone
remodeling state.
Vitamin D also modulates cell growth, inflammation reduction mechanism, nerve
signaling, neuromuscular transmission, immune system functions, and regulates genes involved
with cell proliferation, differentiation and apoptosis. Let alone that, B complex vitamins known to
foster deep sleep are also produced by intestinal bacteria which require vitamin D to thrive, thus
low vitamin D levels can goof up your sleep.
What diseases are linked to vitamin D deficiency?
The unavailability of the vitamin D from the sources give rise
to severe problems like:
Rickets affects children the most, as calcification does not occur resulting in weak bones.
Symptoms include bowed legs, beaded ribs, pelvic
deformities, abnormal spinal curvature, projections of the
breast bone and frequent bone fractures.
Osteomalacia is
an adult form of rickets, affecting women the most.
Symptoms include bowed legs, stooped or bent-over
posture, increased bone fractures, achy bones and poor
muscle strength and tone.
Osteoporosis could be caused in
part by a lack of vitamin D3. The hip, wrist and vertebrae
are the most likely to lose bone mass and fracture.
Medical conditions related to its levels
A person is said to be vitamin D sufficient when serum levels of 25-hydroxy vitamin D are around
30-32 ng/mL whereas a desirable and safe range to significantly rule out any concerns related to
vitamin D deficiency or toxicity is 30-100 ng/mL.
A. Hypovitaminosis D
Also known as vitamin D deficiency, it results when serum levels of 25-hydroxyvitamin D fall
less than 20 ng/mL with constant elevation of PTH and reduced intestinal calcium absorption.
Such is the severity of this condition that its prevalent in epidemic proportions, affecting around
70%-100% of the population in a tropical country like ours despite plentiful of sunshine.
Individuals are mostly unaware of being vitamin D deficient; and only realise when it manifests
in the form of:
Rickets - Softening, weakening and bowed long
bones with deformities in limbs, etc. in children and breast-fed infants exposed to
nil/less sunlight.
- Abnormal softening of skull
- Bone tenderness
- Muscle weakness
- Widening of wrist
- Impeded growth
- Skeletal deformations
Osteomalacia - Softening of bones in adults as a result of insufficient levels
of available calcium and phosphate due to inadequate bone mineralisation.
- Muscle weakness
- Walking difficulties
- Diffuse bone and joint pain
- Bent and fracture prone bones
- Diminished stature
Hypervitaminosis D
This condition of vitamin D toxicity is characterised with serum levels of 25-hydroxyvitamin D
greater than 150 ng/mL and usually results upon excessive intake of vitamin D supplements
while treatment of existing health conditions such as tuberculosis, liver and kidney diseases, etc.
UV exposure can't cause vitamin D overdose as the skin reaches equilibrium after sometime and
vitamin D degrades as fast as it is produced
- Vomiting, nausea
- Excessive thirst and urination
- High blood pressure
- Involuntary muscular contractions (Tetany)
- Weakness and oral defects
Abnormally excessive levels of vitamin D build-up in liver or kidneys upon small accumulated doses
for prolonged periods or sudden overdose of vitamin D may lead to stones, kidney damage or failure,
hardening of arteries and soft tissues, and excessive bone loss.
What is the main function of vitamin D?
Vitamin D plays an important role in many
normal body functions, including:
Regulation of cell growth.
Bone formation.
Immune function.
Muscle strength.
Hair growth.
Fighting infections.
Reducing the risk of autoimmune
diseases.
Vitamin D Level
How does vitamin D work in the body?
The important functions of vitamin D are:
Vitamin D promotes the body's absorption of
calcium and its efficient utilization,
which is essential for the normal development and
maintenance of healthy teeth and bones.
It functions more like a hormone. Calcitriol,
the most metabolically active form of vitamin D,
works with parathyroid hormone (PTH) to maintain
proper levels of calcium in the blood.
It plays an
important role in regulating cellular growth and
functions in our brain cells.
Is vitamin D chronic condition?
Vitamin D deficiency over the past five years,
Vitamin D has emerged as one of the key nutrient
deficiencies contributing to risk of many chronic diseases,
including colon cancer, breast cancer, ovarian cancer,
type 2 diabetes, hypertension, and osteoporosis.
Vitamin D toxicity Excessive exposure to sunlight does not lead to
overproduction of vitamin D. Vitamin D toxicity is inevitably
the result of overdosing of Vitamin D supplements.
Ingestion of excessive (mg) quantities of Vitamin D through
supplements can be severely toxic to humans and animals.
Let us now see how Vitamin D is linked to some of the most
challenging diseases of the century.
How does vitamin D affect the heart?
Vitamin D deficiency is associated with substantial increase
in the incidence of hypertension, hyperlipidemia,
myocardial infarction and stroke.
Studies have shown that
vitamin D can lower inflammation by increasing levels of
certain antiinflammatory messengers like the cytokine
named IL-10 (interleukin-10). Research has also shown
that vitamin D can lower blood pressure, probably by
inhibiting a regulatory system called the reninangiotensin
system.
Risk of atherosclerosis increases with age, and so
does the need for vitamin D. Some studies suggest that it
may be difficult to prevent the chronic diseases associated
with Vitamin D deficiency unless the Adequate Intake (Al)
levels set by the National Academy of Sciences in 1997
be treated as minimum standards for vitamin D intake.
Vitamin D Level
Symptoms of vitamin D deficiency
Several initial symptoms can be observed due to deficiency
of Vitamin D like:
- Pain and inflammation in bones ultimately
may result in stooped posture and stiff spine.
Bones become
tender and diffuse especially spine and ribs and chances of
multiple fractures increases.
- Depression.
- Fluctuation in
normal ranges of various parameters like hemoglobin, WBC,
platelets, serum calcium, alkaline phosphatase and parathormone.
- Trace amount of proteins in urine can be observed.
- Immune system weakens.
Sources of Vitamin D
Unlike abundant sources of other vitamins, vitamin D is known to be found in selective foods
- Flesh of fatty fish (E.g.: salmon, mackerel and tuna)
- Fish liver oils (E.g.:Cod liver oil)
- Egg yolks
- Beef liver
Strict vegetarians can opt for fortified products like cereals, dairy products (milk, cheese, etc.),
orange juice, yogurt, etc. for their daily intake of vitamin D. It is also known as the "sunshine
vitamin" for our bodies harbour a unique ability to endogenously synthesise it upon sunlight
exposure; thus adequate levels can be gained by just basking in the sun for 10-15 minutes.
Sunlight synthesises vitamin D!
Moderate sunlight exposure to bare face, legs and arms produces adequate amounts of vitamin D
in the two innermost 'strata' or layers of our skin: strata basale and stratum spinosum, which
already contain its precursor, 7-dehydrocholesterol in large quantities. This precursor reacts with
UVB rays forming vitamin D through thermal energy. This entire process of vitamin D production
is extraordinarily rapid and only a few minutes of sunlight exposure exceed the vitamin D levels
that can be attained from ingesting dietary sources. For e.g: a fair-skinned individual can produce
-20,000 IU of vitamin D in <30 min of sunlight exposure for which one needs to either drink approx.
200 glasses of milk (100 IU/8-oz glass) or take around 50 multivitamin tablets (400 IU/tablet) in
one sitting.
Dark-skinned individuals need more minutes of sunlight exposure compared to fair-
skinned folks to attain adequate vitamin D levels as higher melanin content in the darker skin allows
less UVB to penetrate the skin, affecting the skin's ability to activate 7dehydrocholesterol, causing
less vitamin D production.
Is it OK to take vitamin D everyday?
Excessive sun exposure does not result in vitamin D
toxicity because the sustained heat on the skin is thought to photodegrade
previtamin D3 and vitamin D3 as it is formed. In addition, thermal activation
of previtamin D3 in the skin gives rise to various nonvitamin D forms that limit
formation of vitamin D3 itself. Some vitamin D3 is also converted to nonactive
forms. Vitamin D supplement are often taken by people in the form of tablets,
capsules, powder, etc.
Supplemental Vitamin D comes in two forms
1. Ergocalciferol (Vitamin D2)
2. Cholecalciferol (Vitamin D3)
But remember, excessive consumption of vitamin D, may result in
Vitamin D toxicity hence it is advisable to initiate any treatment with
due consultation of your physician and after checking with the current
levels of Vitamin D.
Who should do vitamin D test?
vitamin D deficiency test is recommended for those who fall in below category
1. Post menopausal women.
2. People who normally stay indoors for most part
of the day which includes office going people,
home makers, etc.
3. Vegetarians.
4. People who
complain of frequent joint pains.
RANGE Deficiency range Insufficiency range Normal range Intoxication
range VALUE <20 ng/ml 20-30 ng/ml 30-100 ng/ml > 100 ng/ml
How do you test for vitamin D deficiency?
Diagnosis Diagnosis of these conditions in a patient relies on examination of existing
symptoms, intake of any over the-counter medications and supplements along with evaluation of
their medical history.
Blood tests
One of the most simplest and efficient tests to assess vitamin D deficiency or toxicity wherein a
blood sample is taken to estimate the levels of 25hydroxyvitamin D.
Urine tests
A 24-hour urine calcium test is done to estimate the levels of calcium excreted in the patient's
urine which if present around 100-250 mg/dl is considered normal. Any value lower or higher
than the recommended range indicates vitamin D deficiency or vitamin D toxicity, respectively.
Imaging tests
In medical conditions like rickets and osteomalacia, doctors advise the patient
to undergo various imaging modalities like Dual-energy X-ray absorptiometry (DEXA), ultrasound,
Computed Tomography PET-CT Scan, Magnetic Resonance Imaging (MRI), etc. to test the bones for
their shape and deformities, bone mineral density evaluation, etc.
Vitamin D fends off Cancers, says research!'
Be it colorectal cancer or breast cancer, an optimal vitamin D serum levels are known to boost our
immune system to ward-off tumours, disrupt angiogenesis, reduce inflammation, thus delaying
disease progression. It has also been found that higher levels of 25-hydroxyvitamin D lowers the
risk of anemia by boosting hemoglobin levels and is also associated with erythropoiesis through
an yet-to-be understood mechanism. Current research findings have shown that low vitamin D
levels can cause high blood pressure, depression in otherwise healthy individuals and activate
genes linked to autoimmune diseases like multiple sclerosis, neuro-degenerative diseases like
Alzheimer's, cardiovascular diseases and chronic illnesses like Type 2 diabetes.
Maintaining vitamin D levels - An easy yet a challenging task!
Present day's generation, from kids, working folks to the elderly, mostly stay indoors. Yes,
hard to believe but with the advent of technology and smartphones, kids prefer either playing
computer games or browsing through social media. The working men and women hardly make
any time to bask in the morning sun for few minutes due to early morning laziness or rigid office
schedules. Using sunscreens is advisable if one is heading out in a scorching afternoon but
applying it during early sunny hours does no good to the skin, for
it blocks all UVB rays entering the skin, therefore hampering the natural vitamin D production.
If we think hard, we barely expose ourselves to the morning sun; and with fewer dietary sources
of vitamin D available, maintaining its optimal levels has become a task. Exposing bare limbs to
sunlight while staying indoors through a glass window or door doesn't let UVB rays essential for
vitamin D activation, fall on the skin as glass blocks them from passing through, thus is not an
effective mode to attain adequate vitamin D.
How to attain normal Vitamin D levels?
Bask in sun or go for a morning walk for 10-15
minutes before 9 am regularly at least thrice a
week
Ample intake of vitamin D rich foods along with
timely intake of supplements (if vitamin D deficient) as prescribed by the doctor.
Do not ignore persisting clinical symptoms mentioned above and opt for a proper health
checkup
Previously linked to only bone health, it's now wellknown that irregular vitamin D level is
responsible for minor health condition such as fatigue to even grave, life-threatening diseases
like cancers, thus making it an essential nutrient to be required on a daily basis. Nature has
bestowed us with sunlight, indeed an economical way to attain optimal vitamin D levels as a
giveaway in minimal time, therefore don't shun the sun and get this 'sunshine' vitamin - a key players
maintaining your overall health.
Vitamin D is measured
by taking into account the value of:
25 (OH) or 1,25 (OH) vitamin D -
which directly relates to the body's storage.
However 1,25 (OH)
being unstable molecule, the preferred test worldwide is Vitamin D3
also known as 25(OH) Vitamin D3.
Apart from this it is suggested to do
Parathromone, serum calcium and serum phosphorus for a better
understanding of the bone status.
Vitamin D Level
Is taking vitamin D good for arthritis?
Vitamin D deficiency has been linked to bone and joint pain
and in many patients, regulating Vitamin D levels has
resulted in a minimization or elimination of pain. Many
doctors attribute the increase in joint pains seen during
the colder winter months to lack of sunlight and decreased
production of vitamin D.
Arthritis can stem from an inadequa
te amount of the vitamin D and may even worsen from the
deficiency. Research studies have revealed that low levels
of Vitamin D can radiate chronic pain symptoms for those
suffering from arthritis, whereas a sufficient level of Vitamin
D can relieve arthritis pain (and in some cases even
eliminated the pain altogether). Vitamin D seems to stall the
breakdown of cartilage.
Is Vitamin D good for cancer patients?
Vitamin D deficiency is extremely
common in patients with all types of cancer.
Cancer is a
disorder which involves uncontrolled cell growth.
Vitamin D regulates the production of proteins that are
responsible for cell division and growth. Therefore,
vitamin D deficiency can cause abnormal production of
these proteins. Cancer patients who are vitamin D deficient
can experience muscle and bone discomfort and fatigue.
These symptoms may also be caused by radiation therapy,
chemotherapy, or the cancer itself. Vitamin D deficiency
can also cause nonspecific aches and pains in the bones and
muscles as well as feelings of weakness.
