Vitamin D is a fat-soluble vitamin (actually a group of prohormones) which exists in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), of which vitamin D3 is the easiest for the body to absorb. Vitamin D is needed so the body can maintain a correct balance between calcium and phosphate. The balance is important for the formation of bone tissue and for the nerve system to function properly. Vitamin D also affects the immune system, restricts uncontrolled cell division, and reduces high blood pressure. A mild vitamin D deficiency can lead to many health problems like cramps, loss of energy, loosening of the teeth, and an increased pulse. Severe vitamin D deficiency can lead to rickets, also known as 'the English Disease', an umbrella term for insufficient storage of calcium and phosphorus in the bones. Vitamin D deficiency in children can lead to a variety of problems related to bone tissue, such as soft and pliable bones, a fontanelle which closes slowly, and slow development of teeth.
Leading researchers in the American Journal of Clinical Nutrition say vitamin D deficiency among the European population is evident and worrying.
How is Vitamin D produced?
Vitamin D3 is produced when the ultraviolet rays of the sun reach the cholesterol in the skin. The use of sun factor 8 reduces vitamin D production with 95%. In addition, the sunlight in the Nordic countries is only strong enough during the period from March to October for the production of vitamin D. Vitamin D3 can also be absorbed through your diet, primarily through fat fish, cod-liver oil, and egg yolk. Vitamin D2 can only be absorbed through vegetables.
3 000-4 000 units per day
Dr Michael Holick, probably the world's leading authority on vitamin D, says the following: "I treat my patients, on average, with 3 000 units of vitamin D per day. It's been very efficient. I've published a paper where, over a six-year period of time, most of my patients have been on a 3 000-units per day, between 40 and 60 nanograms per millilitre and there is no toxicity. If you're obese, you need two to three times more vitamin D... But for my patients who are at a normal weight, usually 3 000 to 4 000 units per day is adequate to maintain a healthy blood level of 25-hydroxyvitamin D. I personally take 3 000 units per day. My blood level, on average, is about 55 nanograms per millilitre."