I was three or four and I remember squatting in my underpants wearing dark goggles staring, mesmerised, at a vivid bright blue light which fizzed and popped loudly. The air smelt dangerously acrid.
Being a compliant child, I sat quietly along with several of my peers in a semi-circle around this somewhat threatening pseudo-sun. The mercury vapour lamp was, of course, cracking out ultra-violet light, and its purpose was to prevent rickets – soft bones – then known as the common and potentially lethal “English Disease”.
By 1932 vitamin D had been identified in cod liver oil, but it was correctly surmised that sunlight played a major role in its formation by the body. Sadly, my parents’ impressive but primitive mercury vapour lamp most likely only emitted UVA and UVC – not the UVB which specifically triggers the formation of the vitamin D precursor in the skin.
Sunshine is crucial for the formation of vitamin D in the body, as very little vitamin D is present in our natural diet; as aforementioned, it’s in oily fish, and also certain varieties of mushrooms. But skin exposure to sunlight is necessary to achieve anything close to a full quota of the vitamin, throwing new light (so to speak) on the dilemma: bikini or burqa?
To have some understanding of the importance of the “sunshine vitamin”, you need to know that its presence is necessary for the health of teeth and bones in both children and adults; for the efficacy of the immune system in fending off viral and bacterial infections (especially seasonal diseases) as well as some cancers (notably prostate, breast and colorectal), and in guarding against auto-immune diseases such as multiple sclerosis and inflammatory bowel diseases (Crohn’s disease, ulcerative colitis).
Vitamin D deficiency is associated with high blood pressure, accumulation of cholesterol plaque and calcification in the arteries, and diabetes types 1 and 2 – as well as acute events such as heart attack and stroke.
Recent research has shown that a total of more than 900 gene variants controlling 80 metabolic processes are influenced by vitamin D – including three responsible for DNA repair, vital to protection against cancer and any premature effects of old age.
It is estimated that 88.1% of the world’s population has inadequate vitamin D levels.
Also recently discovered is the positive association between male fertility and vitamin D levels, and the correlation of testosterone production with vitamin D levels. Athletes benefit significantly from sunshine as their levels of testosterone respond, improving strength and endurance.
The consensus of medical opinion is that a daily intake of vitamin D, from all sources, should be between 2000 and 5000 iu in order to maintain a healthy level in adults, especially during winter months in northern latitudes. This is not achieved from sunlight and food alone: we all need year round supplementation.
The Wellman Clinic has its own brand of Vitamin D3, cholecalciferol. Each gelatine capsule contains 1000 iu dissolved in olive oil to aid optimal absorption. A container of 360 capsules is £29 (postage and packing, £4).