What this means in layman's terms is those people with higher blood pressure generally have low vitamin d status and people with high vitamin d status usually have lower blood pressure.

This explains the fact that during the summer as you get more sun exposure your blood pressure generally goes down and in the Winter as your vitamin d status declines your blood pressure tends to rise.

But knowing this happens gives us a cheap easy way to reduce this seasonal difference by taking Vitamin D3 supplements during the Winter sufficient to maintain our summer higher Vitamin D status.

How much Vitamin D3 Cholecalciferol you need to take depends on where you live and what your current status is (how much time you spent in the sun this summer?)

This says The late winter average 25-hydroxyvitamin D in the US is about 15-18 ng/ml= 37.5- 45nmol/LSo to go from 37.5 nmol/L to the level that is associated with the lowest cancer incidence 137.5nmol/l - 55ng/ml (thereby cracking not only the BP problem but reducing cancer risk simultaneously) means you have to raise status by 100nmol/l and each 400iu tablet raises status by about 9nmol/L so 4000iu/daily is needed.

The Science Daily article suggests 2000 IU/day, plus, when weather allows, a few minutes in the sun with at least 40% of the skin exposed, for a meaningful reduction in breast cancer incidence, unless the individual has a history of skin cancer or a photosensitivity disease.

I live a lot further North than does Garland (the cancer/vitamin d researcher and I take 5000iu/daily except when I can spend time getting full body sun exposure. Bruce Hollis (a famous vitamin D scientist) says "No one should have a circulating 25(OH) D level—this is the metabolite that defines nutritional vitamin D status—less than 80 nmol. I try to keep my own level at 125 nmol minimum and consume between 2,000-8,000 IU/day depending on the season"

The Vitamin D council website has links to lots more vitamin d research and it's links page has some cheap sources of effective strength Vitamin D3.

In case anyone is wondering why I keep mentioning D3 and not just Vitamin D it's because The case against ergocalciferol (vitamin D2) as a vitamin supplement shows us that the form of Vitamin D our doctors prescribe is better placed in the garbage than in your body. It is less effective, shorter lived less reliable and MORE EXPENSIVE. So do ask when you buy your Vitamin d that it is the most effective most reliable most effcient form D3 CHOLECALCIFEROL.

Post edited by: Ted_Hutchinson, at: 08/30/2007 14:51

Something like Carlsons 2000iu should be fine if you just want to sustain an already reasonable vitamin d status through the winter.

If you haven't been regularly outside in direct sunshine (without sunscreen/sunblock/spfcosmetics) for at least 10-20 minutes 3-4 times a week, it is reasonable to assume your vitamin d status will be approaching 40nmol/L. 80nmol/l is the level associated with optimal uptake of calcium.

Each 400iu of vitamin d raises status by 9nmol/L.

To get from 40nmol/l to above 80nmol/l requires around 5 x 400iu capsules =2000iu.

80nmol/l is the level associated with a 72% drop in colon cancer incidence so is worth aiming for.

130nmol/l is associated with a 50% lower risk of breast cancer and peak muscle performance but to reach that in winter, would need something like Biotecs 5000iu. Taken 5 times one week and 6 the next to average 4000iu/daily over the fortnight.

During the Summer (April-September northern hemisphere) if you get outside into direct sunlight regularly then cutting back to 1500iu-2000iu/daily should be fine. You can still use the 5000iu capsule but just take 2-3 weekly. Vitamin D is fat soluble so you take it with food and it stays around for 10days or so, it isn't washed out in the urine within hours, so taking your Vit d once weekly or spread through the week doesn't (unless you are breast feeding) matter.

If you are breast feeding then an effective amount (at least 4000iu/daily) needs to be taken to ensure the baby gets vitamin d naturally from the breast milk.

Risk assessment for vitamin D