In a recent study, 9,400 patients had an average vitamin D level of 19.3 nanograms per milliliter - levels of 30 are generally considered "normal". At their next follow-up visit, 50% of patients had raised their vitamin D levels to above 30 nanograms per milliliter.
Compared with patients whose vitamin D levels were still low, patients who raised their vitamin D levels were 33% less likely to have a heart attack, 20% less likely to develop heart failure, and 30% less likely to die between the two visits (source: WebMD).
"While normal has generally been considered to be 30, some people have suggested 40 or 50 is better. People who increased their vitamin D blood level to 43 nanograms per milliliter had the lowest rates of heart disease and stroke. But increasing it beyond that, say to 60 or 70, offered no greater benefit."
One of the BMJ blogs calls vitamin D "the elixir of life", but it all starts to sound a bit too good to be absolutely true.
Serum 25(OH)D.
The circulating half-life of 25(OH)D is 2 weeks. This is the best test to determine vitamin D status. A 25(OH)D level of less than 32 ng/mL is considered vitamin D insufficient because intestinal calcium absorption is optimized at levels above 32 ng/mL.
A 25(OH)D level of less than 15 or 20 ng/mL have been used to define vitamin D deficiency.
Parathyroid hormone levels start to rise at 25(OH)D levels below 31 ng/mL, which is another marker of vitamin D insufficiency. Although not always required for the diagnosis of vitamin D insufficiency, a serum PTH may be used to help establish the diagnosis of vitamin D insufficiency.
The word vitamin was originally derived from Funk's term "vital amine."
References:
Vitamin D Supplements Lower Heart Disease Risk. WebMD.
