Residing in a land of year-round sunshine & outdoor lifestyle, it may come as a revelation that many people here in Australia are Vitamin D deficient. Vitamin D (as Cholecalciferol) is synthesized from sunlight when our bare skin is exposed to it. In a further conversion cascade involving enzymes from the liver & kidneys, the active & most potent form of Vitamin D - termed Calcitriol - is produced & stored in the liver & to a lesser extent, the tissues of the body.
Although commonly referred to as a "vitamin", Calcitriol is a biological response-modifying steroid hormone - considered the most potent steroid hormone in the body.
Vitamin D is essential for the active absorption of Calcium & Phosphorus from the gut. It then regulates their utilisation within the body. Vitamin D is integral to the production & balance of cells that constantly remodel our bones - these cells are known as osteoclasts & osteoblasts. Vitamin D also helps prevent Calcium and some other minerals from being excreted via the kidneys.
Vitamin D deficiency is known to be associated in osteoporosis, diabetes, high blood pressure, 'stroke', heart disease, depression, body muscle mass wasting, gum disease, & certain forms of cancer. Sutherland et al (1992) postulates Vitamin D deficiency is linked to the neuro-degeneration of Alzheimer's disease.
The potential to develop autoimmune conditions such as alopecia areata, vitiligo, psoriasis, & inflammatory bowel disease is believed to increase with Vitamin D deficiency. Collectively known as a T-Helper 1 cytokine-mediated inflammatory disorder - the symptoms & prognosis of these diseases may be significantly improved with Vitamin D supplementation (up to 10,000 IU per day). Physiological doses of Vitamin D alter gene response, thereby reducing T-Helper 1 (white blood cell) cytokine/chemokine levels & activity.
A recent paper by Cannell et al (2006) proposed a convincing correlation between Vitamin D supplementation & an increased resistance to seasonal epidemic influenza.
If we totally avoid the sun, our bodies require around 4,000 International Units (IU) i.e. 100 micrograms of Vitamin D per day. Approximately 20-30 minutes of strong sunlight on bare, non-sun screened skin will produce approximately 20,000 IU of Vitamin D - providing a ready reserve of stores. Once these levels are achieved, the skin combines with ultra-violet light to limit Vitamin D production; corrupting excess Cholecalciferol so it cannot be further converted. According to Vieth (1999) there has never been a substantiated case of Vitamin D toxicity from sun exposure alone.
A Vitamin D deficiency may also be nutritionally related - malabsorption being one example. Disorders of the liver may impair Cholecalciferol conversion (termed hydroxylation), or a medication-induced deficiency: taking Phenytoin Sodium (Dilantin) in long-term anti-convulsant therapy.
Vitamin D can be toxic when large amounts (i.e. 40,000 IU) is supplemented for prolonged periods of time.
Darker skinned people such as full-blood Aborigines, Pacific Islanders, or African immigrants need five to ten times longer exposure to synthesise the same amounts of Vitamin D that a fair skinned person would produce in 20-30 minutes. Because of this, dark-skinned folk are at greater risk of Vitamin D deficiency when removed from their traditional environment.
Dietary sources of Vitamin D are egg yolk; 'oily' fish such as salmon & sardines, cod liver oil, Vitamin D fortified bread & cereals, or milk. Be mindful though a standard glass of milk will provide about 100 IU of Vitamin D only, so in Australia sensible sunlight exposure remains the safest, easiest, & most effective method to maintain optimal Vitamin D levels.
Assessing Vitamin D levels is achieved via blood pathology for 25-OH Vitamin D. The standard reference range is 40-170 nmol/L - levels less than 50-80 nmol/L may be associated with Vitamin D deficiency according to published guidelines, whilst the optimal level is 125nmol/L.
Vitamin D supplementation should be prescribed by a Medical Practitioner after Vitamin D blood levels are established. Vitamin D3 - known as Cholecalciferol - is the only form of Vitamin D supplement that should be taken, as it's the one naturally-occurring form for our bodies. All other forms of Vitamin D are metabolic or chemical alterations.
About the Author: Tony Pearce RN is a specialist trichologist and a registered nurse. He is a founding member of the Society for Progressive Trichology. Tony has a clinical practice in Sutherland & Rozelle NSW. He is the Clinical Director for Trichology of Virginia/DC in the United States. In Australia he can be contacted on 02 9542 2700, or through his website at www.hairlossclinic.com.au
*A qualified Trichologist has studied & successfully completed a recognised Academic Trichology Educational Program. References for this article are available on request.Copyright Anthony Pearce 2006.