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.
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True science, not the science as illustrated by Global Warming freaks, is the endless search for the truth of our physical world.
It’s not any more complicated than that.
Making
Yes, that’s what true science is.
Since I regard the Bible as truth, I reject any Science that denies Scripture.
I am happy to explore verifiable scientific fact.
Here is the best article on Vitmin K
NOW brand vitamins makes a good Vitamin K
NOW is a very good company with nice lower prices
http://www.nowfoods.com/m102225.htm
Just as the true church is filled with false prophets, science is filled with false prophets claiming to be scientists.
All of us have an obligation to judge and expose both.
Never heard of ‘em, I just Googled.
No sweat.
Thx thx.
“Just as the true church is filled with false prophets, science is filled with false prophets claiming to be scientists.”
Amen to that.
“There is no magic diet, food, pill, or exercise that will make us live forever.”
Of course.
But there is a vast difference between being reasonably healthy into old age and stumbling around with no ability to do anything you enjoy. Most of the research says that eating the right food for your metabolic type and using certain targeted supplements, along with exercise, extends the quality of life, aside from the longevity.
<You might have to pay for the article to find out
I’m a prof in a univ w/a hospital & med school. I guess I could stop being lazy and download the article. : ) I think in the back of my mind I figure they didn’t control for diet because they are looking for pharmaceutical (and vitamins at such high doses they have to be prescribed) answers to problems, not to the power of food.
I’m almost following you, but not quite. Are you saying that blacks diabetics need or don’t need D3?
Odd, it seems like practically everything gives me stomach problems but 5,000 IU D3 is one thing that doesn't! In fact, my IBS is better. People differ, I guess.
I’ve seen my endo and thought I’d come back here and ask some questions.
It turns out I have very low Vit D. The doc put me on 50,000 units, every 2 weeks.
Is anyone else doing the high dosage thing? Any side effects - tummy upset, diarrhea? Are you taking this for years, or just until your levels get up, then you can take regular doses? (and yeah, I shoulda asked my doctor, shoot me.)
I find it was interesting that I had such low Vit D levels, even though I had been taking 1-2,000 units for almost a year. I guess it wasn’t enough.
>One thing I’m curious about is did they control for diet?<
Excellent question!
LOL, hardly, Vitamin D is very much needed. The big Pharmies want you guys to fall for all this crap that suppliments do not work, this is why they are using the FDA to try and get suppliments banned.
A clinical trial led by Mitsuyoshi Urashima and conducted by the Division of Molecular Epidemiology in the the Department of Pediatrics at the Jikei University School of Medicine Minato-ku in Tokyo found that vitamin D was extremely effective at halting influenza infections in children. The trial appears in the March, 2010 issue of the American Journal of Clinical Nutrition (Am J Clin Nutr (March 10, 2010). doi:10.3945/ajcn.2009.29094)
The results are from a randomized, double-blind, placebo-controlled study involving 334 children, half of which were given 1200 IUs per day of vitamin D3. In other words, this was a “rigorous” scientific study meeting the gold standard of scientific evidence.
In the study, while 31 of 167 children in the placebo group contracted influenza over the four month duration of the study, only 18 of 168 children in the vitamin D group did. This means vitamin D was responsible for an absolute reduction of nearly 8 percent.
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