Vitamin D deficiency is widespread in Australia. I was shocked when my test came back with extremely low levels! Vitamin D receptors are present in all tissues and cells, contributes to bone health and regulates the immune system. If it is naturally synthesized by sunlight on the skin, then how can it be so low in sunny Australia? There are a number of internal and external factors contributing to this which we will discuss, and look at how we naturally get Vitamin D, the symptoms and how to recognise if you need to supplement.
Most of our Vitamin D is from sunlight because it is limited in foods. The richest food sources are egg yolk, butter, and fish liver oils, which are all fatty and require good bile and digestive capability.
As long as we don’t cover up with clothing or sunscreen, then we have a chance to obtain from the sun. UVB rays activate Vitamin D on our skin, but cannot penetrate glass. Sitting by a window inside your home or office, or in a car will not contribute to Vitamin D stores. Direct exposure during high UV rays (usually 10 am to 2 pm are the highest depending on the time of the year) stimulates Vitamin D on the skin.
Vitamin D conversion pathway.
Conversion begins on the skin with 7-dehydrocholesterol in the skin converting pre-vitamin D3 to Vitamin. Next, Vitamin D binding protein carries Vitamin D3 synthesised in the skin to the liver where 25-hydroxylase hydrolyses it to 25-Hydroxyvitamin D (25(OH)D). It is then activated in the kidney by 1α-hydroxylase enzyme (CYP27B1) to 1α-dihydroxyvitaminD (1,25(OH)2D)and binds to the vitamin D receptor.
If there are any physiological inadequacies causing decreased enzymes, decreased kidney or liver function, then Vitamin D will not convert effectively if at all, which is why low levels are considered pandemic in the elderly population.
Symptoms of deficiency
- Burning in the mouth and throat
- Softening of bones and teeth
- Skeletal abnormities, demineralized bone
Vitamin D is often indicated in skin conditions and lowered immune conditions, plus it regulates calcium and phosphorus.
Toxicity is possible from supplementation causing elevated serum calcium and things like fatigue, weakness, excessive urination, calcifications, kidney impairment, so it is important to check your levels before supplementing. The National Health and Medical Research Council recommended upper limit for adults is 80 µg/day.
Medications can interfere with Vitamin D metabolism and absorption, the most common being corticosteroid medications and any medications preventing fat absorption.
Digestive health along with liver and kidney health is crucial for our Vitamin D levels, so supporting the body is beneficial. You can also read boosting your immune system.