Vitamin D Test Importance Function Deficiency Symptoms Sources Toxicity

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.

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.

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.

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.