Posted on 03/08/2010 5:33:34 PM PST by neverdem
SNOWMASS, COLO. — Serious questions exist about the safety and efficacy of the popular practice of high-dose vitamin D supplementation across a broad swath of the population.
One of these concerns is that not all of the extra calcium absorption promoted by boosting vitamin D is going into bone to prevent fractures. Some of it may actually be taken up by atherosclerotic plaque, increasing the risk of cardiovascular events, Dr. Lenore M. Buckley cautioned at a symposium sponsored by the American College of Rheumatology.
This is of particular concern in patients with known coronary disease and for those at high risk, including individuals with rheumatoid arthritis, systemic lupus erythematosus, diabetes, or psoriasis, added Dr. Buckley, professor of internal medicine at Virginia Commonwealth University, Richmond.
Discussing findings from a recent cross-sectional study involving 340 African American patients with type 2 diabetes, Dr. Buckley said that serum 25-hydroxyvitamin D levels were positively associated with increased calcified atherosclerotic plaque in the aorta and carotid arteries (J. Clin. Endocrinol. Metab. 2010 Jan. 8, 2010; [doi:10.1210/jc.2009-1797]
“The effects of supplementing vitamin D to raise the serum 25-hydroxyvitamin D level on atherosclerosis in African Americans are unknown. Prospective trials are needed,” the investigators said.
Recently, a large prospective randomized trial assessed the effects of using calcium supplements on vascular event rates, but it did not involve African Americans. The trial involved 1,471 healthy postmenopausal New Zealand women who were randomized to receive either supplemental calcium or placebo.
By 5 years of follow up, there were a total of 101 myocardial infarctions, strokes, and sudden deaths in 69 women in the supplemental calcium group compared with 54 such events in 42 control subjects (BMJ 2008;336:262-6).
The numbers needed to treat (NNT) were “particularly disturbing,” in Dr. Buckley's view.
The NNT required for 5 years of supplemental calcium to cause one additional MI, compared with placebo, was 44. The NNT for one stroke was 56. And the NNT to cause one additional cardiovascular event was 29. In contrast, the NNT to prevent one symptomatic fracture was 50.
The vascular event rate was higher in women with high compliance with calcium supplementation. The event rate was also higher during months 30-60 of follow-up, which is consistent with an initial latent period during which undetected vascular damage may occur.
There is a noticeable, if anecdotal, increase in the number of physicians ordering serum vitamin D tests to screen for deficiency. The vitamin D assay has become one of the most-ordered lab tests in the U.S., despite the assay's questionable reliability, its $40-$200 cost, and considerable unresolved debate as to what constitutes an optimal blood level.
In fact, the Centers for Medicare and Medicaid Services is considering denying Medicare coverage for vitamin D tests for screening purposes, according to Dr. Buckley.
There is solid evidence that vitamin D supplementation reduces fracture risk in the elderly, especially in those with low serum levels. But the impetus for the upsurge in vitamin D screening and supplementation is the hope that it might protect against a broad range of chronic diseases, including cancers, dementia, autoimmune diseases, and cardiovascular disease. However, that hope is driven mostly by epidemiologic data, which must be viewed as hypothesis-generating rather than definitive.
The classic example of how misleading epidemiologic associations can be is the expectation that estrogen replacement would reduce cardiovascular risk in postmenopausal women; when the Women's Health Initiative and other prospective trials were eventually carried out, it turned out just the opposite was true, Dr. Buckley noted.
“The question we have to ask is: What does that low serum vitamin D level mean? Is it the thing that predisposes, or is it somehow a byproduct of illness?” she said.
There is intriguing evidence to indicate the optimal level of vitamin D to promote bone health, muscle strength, immunity, and other key functions may vary by race. Data from the National Health and Nutrition Examination Survey show that very few white children aged 1-12 years are vitamin D deficient using the classic threshold of 15 ng/mL. In contrast, about 10% of non-Hispanic black 1- to 6-year-olds are vitamin D deficient, as are close to 30% of those in the 7- to 12-years-old age bracket (Pediatrics 2009; 124: e362-70 [doi:10.1542/peds.2009-0051]).
Many observers see this racial disparity as a public health problem reflecting unequal access to services. But there is a conundrum here: If vitamin D deficiency is rampant in black children, why do they have greater bone strength and muscle mass, on average, than white children?
Such observations make “one wonder whether the definition of normal levels should vary by race,” according to the rheumatologist.
Support for this theory comes from studies showing that pushing serum vitamin D levels to 30 ng/mL or higher in whites reduces their parathyroid hormone levels, while pushing levels above 20 ng/ml in African Americans—young or old—doesn't further decrease parathyroid hormone or increase bone density.
Asked by audience members what she does about vitamin D in her own practice, Dr. Buckley said she generally tries to get patients into the 20-29 ng/mL range, while in African Americans and patients with known cardiovascular disease she aims for 15 ng/mL or slightly more—“and I worry that might be too high sometimes.”
Dr. Buckley added that she reserves expedited supplementation—50,000 IU weekly for 8 weeks—mainly for vitamin D deficient elderly patients at high risk for fracture or fall. That's where there is supporting evidence of benefit. There is no evidence to support supplementation in young or middle-aged patients whose increased fracture risk is decades away.
Like many others, Dr. Buckley eagerly awaits fresh guidance in the form of updated recommendations on vitamin D from the Institute of Medicine.
Rumor has it that the IOM report, due this spring, will recommend an increase in the currently recommended supplemental 400 IU/day for 50- to 70-year-olds not getting sufficient vitamin D from the sun. Her hope is the IOM will address the thorny issues of who should receive supplementation, and how fast it should be done.
Dr. Buckley reported having no financial conflicts of interest relevant to her talk.
The content on this site is intended for health professionals.
Vitamin D, Adiposity, and Calcified Atherosclerotic Plaque in African-Americans
Prevalence and Associations of 25-Hydroxyvitamin D Deficiency in US Children: NHANES 2001–2004
Those two links came with the article.
bump
Before Dr. Buckley starts sounding the alarms bells about dangers of Vitamin D supplementation in relation to atherosclerosis, she might want to investigate the role of Vitamin K2, which studies have shown transports calcium to where it should be, to the bones and away from harmful buildup in the arteries, thereby inhibiting atherosclerosis. Several supplement manufacturers now come D3 and K2 into one supplement:
http://www.vitacost.com/Twinlab-D3-Plus-K2-Dots
You can Google Vitamin K2 and calcium transport and see many links which discuss this research. Not yet accepted, but many studies have shown this to be a role of K2:
And, the darker the skin, the less Vitamin D a person absorbs from the sun. It could be that blacks, who do absorb less from the sun, might actually have a lower need form Vitamin D than whites, who’ve both probably adapted to particular levels of Vitamin D over thousands of years.
<Vitamin D, Adiposity, and Calcified Atherosclerotic Plaque in African-Americans
You can’t win, huh? I just came from my OBGYN nurse practitioner who said I needed to talk to my endo (I’m a black Type II diabetic) about how much D to take. I’ve been taking some, my previous endo recommended that I take it (I started before his recommendation), but never gave an amount. The nurse practitioner said I should get my levels tested so I’d know just how much to take. Now this article suggests maybe I shouldn’t take it. Who knows? I’ll show it to the new endo this week.
One thing I’m curious about is did they control for diet? I’ve been vegan for 2 years. There’s a lot that I don’t eat, especially things that might cause heart problems down the line. So, are the results of the test true for all black diabetics or only for those who eat the standard American diet? I’m just thinking out loud here, I’m not expecting an answer.
Get the test done from your endo. I’m a white type 1 but also take another medication that depletes my vitamin D. Mine was very low and the doc gave me a prescription vitamin which from me ended up cheaper than buying OTC. I think standard does is 2000iu a day but the doc have me a 50,000iu once a week vitamin D. I don’t think vitamin D is one that can be stores or builds up you will lose the excess instead.The heart problems are worrisome just because we are more inclinded towards heart problems anyway. Anyone know what the recomended vitamin K dosage is per day?
OOOPPPPSSS have=gave
One thing I’m curious about is did they control for diet?
You might have to pay for the article to find out, unless you can find a medical library in a hospital nearby. I have no idea if a regular library will help you find a professional article like the citation I linked.
FReepmail me if you want on or off the diabetes ping list.
Thanks for the links.
“Anyone know what the recommended vitamin K dosage is per day?”
Everything I’ve seen says around 90 - 100 mcg per day. Here is another one that is K2 only. I’ve used this one or the D3K2 combination for about three years. This one is 100 mcg, page down for ingredients:
http://www.vitacost.com/NSI-Vitamin-K2-MK-7-from-Natto-Extract
One tbs of Cod Liver Oil will give you 340% the recommended Daily value of D.
Seems like the most economical way to get the vitamin.
New method to grow arteries could lead to 'biological bypass' for heart disease
Americans want Uncle Sam's help putting healthy foods on their dinner table (however...)
Two-faced testosterone can make you nasty or nice The original article is a FReebie. Copy & paste the URL.
FReepmail me if you want on or off my health and science ping list.
Cheers!
Science is a work in progress. We don't know what we don't know. Our Creator didn't give us a brain to waste it.
I don’t trust folks from the PTB who are determined to force the world’s population down to 200 million any further than I could throw the moon.
I’ve been taking D3 for some months now and have found a significant difference in my health and resistence to a number of commong maladies.
I plan to take it for some time to come as long as I have a supply.
I’ll put this one up, from Dr. Sinatra who is the first one I saw publicizing K2. He lays out the greatest expectations for K2 for which there is some research to support, though it is not yet accepted by the medical profession . He recommends 150 mcg per day, and his product is expensive. I just put this up for anyone interested, and then they can find a good bit of research on the net to consider. And, there is some research that suggest K2 can even reverse atherosclerosis. But most of us will just have to make our own decisions about it since it’ll be a while before anything is proven.
http://www.drsinatra.com/Products2.aspx?ProductID=MK10
Science is the reason we have such good, long lives. We only have to look at parts of the world that don’t employ science to see what a bountiful life it has given us.
Why disparage that?
With the greatest of respect: there is published science on the differences in both glucose uptake and calcium metabolism in African Americans. A recent 20 year longitudinal study revealed a 2000% increase in early cardiac mortalities in African Americans between the ages of 40 and 50. D3 deficiencies in African American are presumed to be the major causation. It would seem plausible that there is a problematic period in a rapid D3 repletion process where calcium supplementation and elevated parathyroid secretions are responsible for mislaid calcium in smooth muscle tissue. A slower D3 loading process may reduce the parathyroid secretions and reduce this problem.
Thanks! When I am not on the script vitamin D3 I take 2000iu of a softgel D3 OTC so going with the separate is probably the most thrify way to do it. :)
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