Alison discusses the changes to the RDA of Vitamin D, while Aubrey explains Fryette's laws of Spinal Biomechanics in bodywork.

CMTV# 25 Show Notes - 7 Elements to support the Body continued

Nutrition: following on from the A, B, C that our father Don Gowing used, which was discussed in our last episode, it is important to consider the role of Vitamin D

1. How vitamin D is produced in the human body

Skin production (primary natural source)

Vitamin D is not truly a vitamin in the classic sense; it behaves more like a hormone.

When your skin is exposed to UVB radiation from sunlight, a cholesterol-derived molecule in the skin (7-dehydrocholesterol) is converted into vitamin D₃ (cholecalciferol).

This process depends on:

Sun angle (latitude, season, time of day)

Skin pigmentation (darker skin produces less per exposure)

Age (older skin produces less)

Sunscreen and clothing (block UVB)

Activation in the body

Vitamin D made in the skin (or consumed in food) is inactive and must be processed:

Liver → converted to 25-hydroxyvitamin D

Kidneys → converted to 1,25-dihydroxyvitamin D (calcitriol), the active hormone

The active form regulates:

Calcium and phosphate absorption

Bone mineralization

Muscle function

Immune system activity

2. Dietary sources (secondary source)

Vitamin D occurs in two main forms:

Vitamin D₃ (cholecalciferol) – animal sources and skin synthesis

Vitamin D₂ (ergocalciferol) – plant/fungal sources

Common dietary sources:

Fatty fish (salmon, sardines, mackerel)

Egg yolks

Liver

Fortified foods (milk, cereals, plant milks)

Diet alone usually provides far less vitamin D than sunlight.

3. How vitamin D is measured

Blood test used

Vitamin D status is measured using a blood test for:
25-hydroxyvitamin D

This is a useful indicator because it reflects:

Skin production

Dietary intake

Supplement use

Units of measurement

ng/mL (nanograms per milliliter) – common in the US

nmol/L (nanomoles per liter) – used internationally
(1 ng/mL = 2.5 nmol/L) for example 600 units of Vitamin D is 15 mcg and will achieve 26.8 nmol/L

Vitamin D is often stated in I.U’s which stands for international units.

The general recommendation has been 400 to 800 international units. This is a minimum to avoid deficiency. However new research suggests that this is significantly insufficient and is possibly 15 times lower than what is required for health.

4. How much vitamin D do we require per day?

Old daily recommendations (healthy individuals)

(1 mcg = 40 IU)

Safe limit (from all sources)

4,000 IU (100 mcg) per day for most adults

Some individuals (e.g., limited sun exposure, darker skin, obesity, malabsorption, older age) may require higher intake this can be done under medical guidance if necessary.

5. Sun exposure vs supplementation

Short, regular sun exposure can produce thousands of IU in minutes under ideal conditions, it is estimated that 20 minutes of sun exposure can give up to 10,000 i.u’s of Vitamin D. (important to note that the body with its incredible intelligence will stop producing Vitamin D once optimal levels are achieved even with continued exposure)

However, due to latitude and lifestyle, supplementation is often necessary, especially in winter or at higher latitudes (above 50 latitude).

Key takeaways

Vitamin D is synthesized in the skin via sunlight and activated by the liver and kidneys.
Blood levels are assessed using 25- hydroxyvitamin D (25(OH)D) where 50 nmol/L have been shown to benefit bone health and prevent disease.
It was thought that people need 600–800 IU/per day, however this requirement may be nearer to 8,000 IU/ per day and needs vary.
Vitamin D is required for healthy bones, skin, immune system and nervous system.
Both deficiency and excess can cause health problems, particularly affecting bones and muscles. However excess would require a consistent intake of approximately 25,000 IU/ per day for several months.
Vitamin K2, found in fermented foods for example can switch of Vitamin D if levels are getting too high in the blood.

Fryette's Laws describe how the spine moves. Law 1 & 2 apply to the Thoracic and Lumbar spine, while law 3 applies to the entire spine.

Law I - side bending and rotation occur in opposite directions (Neutral Mechanics), (The Group Rule ). When the thoracic or lumbar spine is in a neutral position (not flexed or extended) side-bending and rotation happen in opposite directions. This describes the broad, sweeping curves across several vertebrae. It's a Type I dysfunction-a group pattern. It's often the body's way of adapting or compensating. It's not the cause -it's the body's solution.
Law II - in a flexed/extended spine (Non-Neutral Mechanics), they occur in the same direction (The Single Rule) . This is your Type Il dysfunction-the "stuck" vertebra that feels sharp and local.

Law III- motion in one plane affects motion in others (limiting mobility) - The Coupled Motion Principle. When motion is introduced in one plane, motion in the other two planes is reduced.