Vitamin D

Question 1

Vitamin D

Answer 1

• Vitamin D is not strictly a vitamin since it can be synthesised in the skin in response to sunlight.
• Dietary sources are only required in the absence of adequate sunlight (UVB), and include 2 types of vitamin
- Plant source: vitamin D2 (ergocalciferol D2) found in mushrooms (fungi), but these require good sun
- Animal source: vitamin D3 is 7 dehydroxycholesterol (cholecalciferol D3) found in cod liver oil, oily fish (herring, mackerel, sardines, wild caught salmon) and organic egg yolks.
• Vitamin D2 and D3 do not have any direct functions; they both first need to be converted (hydroxlyated).
• D2 and D3 have the same activation pathway via the liver and then kidney.

Question 2

Vitamin D: Levels

Answer 2

• Conventional medicine often considers serum ranges (of calcidiol ) over 50 nmol/L to be sufficient.
• Below 25 nmol/L is almost universally agreed to be deficient.
• However , the optimal range is generally considered to be 75-125
nmol/L (some variance). So are your clients levels ‘sufficient’ or ‘optimal’?

Question 3

Vitamin D Synthesis

Answer 3

• If outside and your shadow is the same height or shorter than you are, you’re getting enough sunlight to make vitamin D.
• Serum levels are usually highest at the end of the summer and lowest at the end of winter.
• Summer: even on cloudy days, UV light can penetrate thin clothes and create vitamin D. Sunscreens and window glass block the conversion to vitamin D by blocking UVB radiation.
• Winter: temperate regions may not have adequate UV for synthesis.
• 10 minutes of summer sun exposure results in endogenous production of about 400IU in fairer skin types. In darker skin tones it can take 3-6 times longer to produce the same amount of D3.
• Note that vitamin D can be stored in the liver for 4 months.

Question 4

Vitamin D: Dosage

Answer 4

• Our focus should be on first addressing the cause of the deficiency, to avoid a ‘symptom based’ approach.
• A supplemental dose of 4000IU/day
has been used without adverse effects. 1 μg of cholecalciferol = 40 IU.
• It is advisable to test vitamin D levels every four months to adjust dosing where appropriate.
•Ergocalciferol is less than one third as potent as cholecalciferol, so D3 is favoured for supplementation. D3 supplements also stay in circulation longer.
• Pronounced deficiency: (<10 ng/mL) 50,000 IU of vitamin D3 orally once weekly for 2-3 months, or 3 times weekly for 1 month.

Question 5

Vitamin D Functions

Answer 5

• A key function of vitamin D is to maintain serum calcium and phosphorus homeostasis. This balance impacts many body processes, including heart and nervous system functioning.
• Vitamin D also performs a variety of other functions in the body.
• The actions of vitamin D are mediated through a nuclear transcription factor known as the Vitamin D Receptor (VDR) within the nucleus of each cell. VDR activation is thought to directly and/or indirectly regulate 100 to 1,250 genes.

Question 6

Vitamin D Effects

Answer 6

Bone Health
Immune function and regulation
GIT Health
Anti-Cancer
Insulin

Question 7

Vitamin D: Bone Health - Functions

Answer 7

• Supports bone density (along with vitamin K2), by increasing intestinal calcium absorption.

Question 8

Vitamin D: Bone Health - Therapeutic Uses

Answer 8

• Osteoporosis

* Osteomalacia & Rickets

Question 9

Vitamin D: Immune Function and regulation - functions

Answer 9

• Supports immune function by:

• Enhancing innate immune system
• Regulation of T helper cells
• Producing antibacterial peptides.
• Inhibiting eosinophils
• Reducing inflammatory cytokines (e.g. IL 6 and TNF α and prostaglandin production.

Question 10

Vitamin D: Immune function and regulation - Therapeutic Uses

Answer 10

• Allergies
• Autoimmunity, e.g. multiple sclerosis
• Infections (e.g. viral and bacterial)
• Musculoskeletal pain reduction

Question 11

Vitamin D: GIT Health- Functions

Answer 11

• The vitamin D receptor (VDR) helps to regulates mucosal inflammation.
• Vitamin D has a role in commensal bacterial colonisation.
• Intestinal VDR stabilises tight junctions.

Question 12

Vitamin D: GIT Health - Therapeutic Uses

Answer 12

• Intestinal inflammation,e.g. inflammatory bowel diseases (as well as intestinal permeability)

Question 13

Vitamin D: Anti-Cancer - Functions

Answer 13

• Enhances the anti tumour activity of innate immune cells.

* Regulates multiple genes through the VDR, and inhibits angiogenesis.

Question 14

Vitamin D: Anti-Cancer - Therapeutic Uses

Answer 14

Cancer prevention and support

Question 15

Vitamin D: Insulin - Functions

Answer 15

• Vitamin D:

• Activates transcription of the insulin gene (increasing insulin secretion).
• Increases cellular sensitivity to insulin.

Question 16

Vitamin D: Insulin - Therapeutic Uses

Answer 16

Diabetes Mellitus (Type 2 but also Type 1)

Question 17

Vitamin A and D interaction

Answer 17

• The balance of vitamin A and D is essential for proper gene transcription.
• The Retinoid X Receptor (RXR) is a type of nuclear receptor that is activated by vitamin A.
• Together the VDR/RXR form a complex with DNA for transcription.
• So, from a disease prevention approach, maintaining healthy levels of vitamins A and D is crucial for correct gene expression.

Question 18

Vitamin D Deficiency: Signs and Symptoms

Answer 18

• Rickets & osteomalacia demineralised bones. Rickets occurs in children, whilst osteomalacia affects adults. Presents with bone pain and bowing of lower limb bones.
• Osteoporosis (brittle bones) fractures.
• Severe asthma in children.
• Poor immunity or immune dysfunction (autoimmunity, allergies), insomnia, nervousness, depression.
• Menstrual irregularities (increases FSH / LH production).
• Non specific musculo- skeletal pain and fatigue

Question 19

Vitamin D Deficiency Causes

Answer 19

• Inadequate UVB sun exposure and overuse of conventional sunscreens.
• Dietary factors such as excessive animal protein or calcium intake can lead to lower blood levels of vitamin D by affecting its rate of formation and clearance.
• Lack of dietary fats (it is a fat soluble vitamin), and a lack of magnesium (it is a co factor for vitamin D synthesis.
• Breastfeeding without adequate sunlight / supplementation.
• Impaired liver functionality (compromised vitamin D conversion) due to excess alcohol, drug and caffeine use, as well as a large toxic burden from the diet (e.g. pesticides), environmental and household chemicals. Therefore, it is crucial to support liver functionality by removing the toxic burden, etc.
• Elderly patients and those with a history of kidney disease.
• Poor intestinal absorption of dietary vitamin D (e.g. due to cystic fibrosis, coeliac disease, dysbiosis) and a lack of bile. Therefore, it is crucial to support digestive health (i.e. good digestive secretions, a healthy microflora

Question 20

Vitamin D Toxicity

Answer 20

• Vitamin D synthesis due to sunlight does not produce toxicity.
• Main toxicity symptoms due to vitamin D related hypercalcaemia : nausea, diarrhoea, vomiting, weakness, hypertension, constipation.
• Toxicity can occur taking supplemental vitamin D at more than 50,000 IU per day for one to several months
• Individuals with vitamin D toxicity usually have blood levels above 375 nmol/L
• EFSA Tolerable Upper Intake Level for Adults: 4000 IU/day.