Vitamin D –The Sunshine Vitamin

Vitamin D is a critically important nutrient. The main source of vitamin D is sunlight. However I suspect sunlight gives benefits above and beyond that of Vitamin D alone.

There is now strong evidence that moderate sunbathing and having higher levels of Vitamin D in the blood lowers the incidence of 17 types of cancers (including breast, ovary, prostate, colon, bladder, non-Hodgkins lymphoma), heart disease, stroke, diabetes, birth defects and depression. There is also a link between low vitamin D levels and chronic pain and Vitamin D has been shown to ease symptoms of back pain in 95% of one group studied. Another study found vitamin D gave a 33% reduction in type 2 diabetes and another found it reduced fractures by one third. Sunlight strengthens muscles (in one study reducing falls in the elderly by 19%) and increases heart output by 40% It also lowers cholesterol, lowers sugar, lowers blood pressure, strengthens muscles, protects against multiple sclerosis, improves absorption of calcium and magnesium, boosts immunity, protects from infections, and doubles the lifespan of laboratory mice. Not bad for one vitamin.

The ideal level of Vitamin D should be above 75nmol/l but levels tend to be low in the UK and levels above 50nmol/l are acceptable. It is difficult to get adequate Vitamin D from food although oily fish and mushrooms do contain a little. Typically sunbathing, long enough to get slightly red, in a bathing costume, will provide 10,000 to 20,000 units of Vitamin D within an hour or so. Although I am an advocate of sun exposure please be aware that excess sunbathing in the middle of the day in the middle of summer can increase the risk of some skin cancers. So get plenty of sunshine but don’t binge on it and avoid the most dangerous times!

Some recent work published in a major medical journal suggest the ideal daily dose of Vitamin D should be 2,600iu daily and world expert on Vitamin D, Dr R Veitch, recently completed a study which found regular consumption of 4000 iu was safe and kept Vitamin D levels stable.

Drugs, especially chemotherapy drugs, have been shown to greatly reduce Vitamin D levels. Cancer does the same. Boston Medical School found the dose needs to be higher in these situations, ideally 5000 iu daily when cancer is active and 10,000 iu daily during chemotherapy.

One advantage of a higher dose is better protection from infections. One study compared people taking no vitamin D with those taking 800 iu daily and with those taking 2000 iu daily. In the group taking no vitamin D there was a total of 31 flu and cold infections over the year; in the group taking 800 iu there were 9 infections in the year, whereas in the group taking 2000 iu daily there was only one infection. Dr Veitch says that the maximum that should be taken in a day is 40,000 iu. This is a huge amount and what this means is it is almost impossible to take too much.

I would suggest that the best way to get Vitamin D, apart from sunbathing, is to get it from a health food shop and to use colecalciferol (Vitamin D3) at about 5000iu daily for 2-3 months if you are deficient. For routine use aim for 1000 to 2000iu daily. Almost everybody needs 2000iu daily in winter and 1000iu daily in summer. (During the summer take it in the evening to allow your body to make natural Vitamin D from sunlight). Sometimes the amounts can be confusing as they are given in µg. Note 25µg is the same as 1000iu.

There is another form of vitamin D called D2 or ergocalciferol. It is best not to use this form as it has only a quarter of the strength of Vitamin D3 (colecalciferol). You can buy supplements containing 1000 iu (25µg) at health food shops. For children drops are available. Children with low levels can have up to 5000iu daily if under 6 months and up to 8000iu if over 6 months. Take this for 2 months then use 200-400 iu for routine use in children under 6 months and 400-800 in those over 6 months. The recommended intake in pregnancy is 400iu daily but American data suggests the optimal amount is nearer 2000 iu daily. A fascinating 30 year study from Finland showed that taking 2000iu Vitamin D in pregnancy reduced the rate of type 1 diabetes in their children by 80%. Vitamin D is remarkably safe even at high dosage but take care if it is mixed with other nutrients (it is sometimes combined with calcium or Vitamin A).