Vitamin D

November 15, 2017

vasi - vitamin d


Vitamin D is a fat-soluble vitamin in a family of compounds, including Vitamins D-1, D-2, and D-3, which are obtained from sun exposure, foods, and supplements. Unfortunately, it is only naturally present in very few foods, but can be found added to certain foods and drinks, or as a supplement. It is produced when ultraviolet B rays from sunlight come into contact with the skin and trigger Vitamin D synthesis. Scientifically, ultraviolet rays with a wavelength of 290 – 320 nanometres penetrate the uncovered skin and convert cutaneous 7-dehydrocholesterol to previtamin D3, which in turn becomes Vitamin D3. UV radiation does not penetrate glass so sunshine through a window will not produce Vitamin D. This is the same with sunscreen and clothing.

This vitamin is biologically inert and requires two hydroxylation’s in the body for activation. The liver converts the Vitamin D into 25-hydroxyvitamin D (also known as calcidiol), then the kidneys help to form 1,25-dihydroxy vitamin D (also known as calcitriol).

Vitamin D affects as many as 2,000 genes and has many roles in the body, some of which include: bone health, calcium absorption, modulation of cell growth, neuromuscular and immune function, and reduction of inflammation.


  • Supports growth and maintains the health of the skeleton: Vitamin D is essential for the regulation of calcium, and the maintenance of phosphorus levels in the blood. Vitamin D is required to absorb calcium from the intestines which would otherwise be excreted through the kidneys. This absorption of calcium is what prevents bone loss and severe osteopenia. It is also a strong stimulator of calcium deposition in the bones.
  • Reduces the risk of diabetes: Vitamin D stimulates the pancreas to produce insulin. Insufficient levels therefore negatively effect insulin secretion and cause glucose tolerance.
  • Aids with depression
  • Improves muscle function: Vitamin D plays an important role in muscle metabolism and function. It also improves muscle strength, balance, and physical performance. Studies suggest that this vitamin may increase muscle strength by improving atrophy of type II muscle fibres.
  • Aids with healthy pregnancy: Women who are deficient in vitamin D are more susceptible to preeclampsia, gestational diabetes mellitus, and bacterial vaginosis during pregnancy.
  • Lowers blood pressure and improves cardiovascular health: This is thought to be because Vitamin D decreases the production of a hormone called renin, which is believed to play a role in hypertension.
  • Prevents cancer: The hormonally active form of Vitamin D, calcitriol, has been shown to reduce cancer progression by slowing the growth and development of new blood vessels in cancerous tissue. It also induces cancer cell death
  • Increases fertility: Vitamin D has been shown to lower oestradiol and progesterone which is beneficial as estrogen dominance is one of the main causes of infertility.
  • Improves immune support: Vitamin D supports the cells responsible for seeking out and destroying pathogens.
  • Maybe an effective treatment for psoriasis
  • Increases the health of the immune system and reduces the risk of multiple autoimmune diseases such as Irritable Bowel Disease, Grave’s disease, multiple sclerosis, lupus, rheumatoid arthritis, and Crohn’s disease amongst others. Studies now show that there are Vitamin D receptors (VDR’s) located in the nuclei of all immune cells, including antigen-presenting cells, natural killer cells, and B and T lymphocytes. A deficiency in this Vitamin has also been linked to many autoimmune diseases.


The recommended daily allowance (RDA’s) for Vitamin D is as follows:

Male and female 0 – 12 months 10mcg
Male and female 1 – 13 years 15mcg
Male and female 14 – 18 years 15mcg
Male and female 19 – 50 years 15mcg
Male and female 51 – 70 years 15mcg
Male and female 70+ years 20mcg
Pregnant females 15mcg
Lactating females 15mcg


Sources include:

  • Fatty fish such as salmon, tuna, and mackerel
  • Fish liver oils
  • Beef Liver
  • Cheese
  • Egg yolks
  • Certain mushrooms
  • Fortified dairy products
  • Fortified cereals and grains
  • Fortified juices
  • Sun exposure

Most people only get approximately 10% of their required daily intake of Vitamin C from their diet.

It is estimated that sun exposure on bare skin for 5 – 10 minutes 2 – 3 times a week allows most people to produce sufficient amounts of Vitamin D. it must also be noted that Vitamin D breaks down quite quickly, which means stores can run low, particularly in winter.


Deficiency of Vitamin D may cause no symptoms at all.

Levels of Vitamin D are expressed in nanomoles/litre (nmol/L). Levels under 30 nmol/L is considered deficient.

  • Bone and muscle pain
  • Rickets (soft, weakened bones), particularly in children
  • Osteopenia (weak, fragile bones) in older adults
  • Decreased immunity and frequent illness or infections
  • Fatigue and tiredness
  • Depression
  • Impaired wound healing
  • Hair loss
  • Loss of concentration
  • Muscle weakness
  • Frequent bone fractures and loss of bone density
  • Insulin resistance
  • Frequent illnesses or infections


Deficiency can also cause obesity, multiple sclerosis, cancer, type 1 and 2 diabetes, hypertension, heart disease, mental health conditions, cognitive decline, Alzheimer’s, and certain autoimmune diseases.

Doctors can diagnose Vitamin D deficiency by performing a simple blood test. If found to be deficient in this Vitamin, the doctor may then order X-rays to check the strength of the patient’s bones.


  • People with dark skin: The pigment in skin (melanin) acts as a filter for UV radiation and therefore reduces the amount of Vitamin D produced in the body.
  • People with little to no sun exposure: These people need to consume adequate amounts of Vitamin D through diet and supplements.
  • Elderly and housebound people
  • People who cover most of their body for cultural and religious reasons
  • People who avoid the sun for cosmetic or health reasons
  • People who are hospitalized or institutionalized for prolonged periods of time
  • People with occupations that have little to no sun exposure aka office workers or night shift workers
  • People with a disability or chronic disease
  • People with health conditions including obesity, kidney disease, end-stage liver disease, cystic fibrosis, coeliac disease, and inflammatory bowel disease.
  • People who use certain medications which increase the breakdown of Vitamin D
  • People who adhere to a strict vegan diet
  • Babies of Vitamin D deficient mothers


The upper-level limit recommended for Vitamin D IS 4000 IU per day, though it has been suggested that Vitamin D toxicity is unlikely at levels lower than 10,000 IU per day.

Known as hypervitaminosis D, excessive consumption of this Vitamin can cause the over-calcification of the bones and the hardening of blood vessels.

The most common symptoms of Vitamin D toxicity are nausea, vomiting, headaches, loss of appetite, dry mouth, constipation, and diarrhea. Other severe side effects of Vitamin D toxicity include kidney stones, kidney damage, muscle weakness, and excessive bleeding. It may also cause allergic skin reactions in select people, facial swelling, and breathing difficulties, and can affect blood sugar levels which can be dangerous for people with diabetes.

Excessive amounts of Vitamin D can cause a condition known as hypercalcaemia which is characterized by elevated blood calcium levels. Symptoms of this include: vomiting, nausea, stomach pain, dizziness, fatigue, confusion, excessive thirst, and frequent urination.

Too much of this vitamin may actually be detrimental to your bone health. This is due to the fact that excessive levels of Vitamin D may lead to low levels of Vitamin K2 in the blood. One of the main functions of Vitamin K2 is to keep calcium in the bones and out of the blood.

This vitamin can also interact with certain medications or other supplements so always consult with a doctor before taking this supplement.

Also, it should be noted that excessive sun exposure can cause skin cancers and skin damage.



Kiara James

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