Poor vitamin D study - IMHO

[annelb]

Calcium/vitamin D supplementation and cardiovascular events. When I saw that title I got excited. I have coronary artery disease and have had low vitamin D levels so I look out for such articles. Then I read the abstract :( They only used 400 IU of vitamin D a day - that is way to low to show anything. The abstract does not mention what the vitamin D levels were in these subjects - gotta find the complete article. What is even worse this is the American Heart Association official journal. :eek:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17309935&query_hl=1&itool=pubmed_docsum
Circulation. 2007 Feb 20;115(7):846-54.Calcium/vitamin D supplementation and cardiovascular events.Hsia J, Heiss G, Ren H, Allison M, Dolan NC, Greenland P, Heckbert SR, Johnson KC, Manson JE, Sidney S, Trevisan M; Women's Health Initiative Investigators.
Department of Medicine, George Washington University, Washington, DC, USA. jhsia@mfa.gwu.edu

BACKGROUND: Individuals with vascular or valvular calcification are at increased risk for coronary events, but the relationship between calcium consumption and cardiovascular events is uncertain. We evaluated the risk of coronary and cerebrovascular events in the Women's Health Initiative randomized trial of calcium plus vitamin D supplementation. METHODS AND RESULTS: We randomized 36,282 postmenopausal women 50 to 79 years of age at 40 clinical sites to calcium carbonate 500 mg with vitamin D 200 IU twice daily or to placebo. Cardiovascular disease was a prespecified secondary efficacy outcome. During 7 years of follow-up, myocardial infarction or coronary heart disease death was confirmed for 499 women assigned to calcium/vitamin D and 475 women assigned to placebo (hazard ratio, 1.04; 95% confidence interval, 0.92 to 1.18). Stroke was confirmed among 362 women assigned to calcium/vitamin D and 377 assigned to placebo (hazard ratio, 0.95; 95% confidence interval, 0.82 to 1.10). In subgroup analyses, women with higher total calcium intake (diet plus supplements) at baseline were not at higher risk for coronary events (P=0.91 for interaction) or stroke (P=0.14 for interaction) if assigned to active calcium/vitamin D. CONCLUSIONS: Calcium/vitamin D supplementation neither increased nor decreased coronary or cerebrovascular risk in generally healthy postmenopausal women over a 7-year use period.

PMID: 17309935 [PubMed - in process]


Grrrrr. I have heard that studies on supplements often show no benefit because the dose is way too low.
Anne

[Ted Hutchinson]

The Vitamin D council comments on the Womens Health Initiative research project (http://www.vitamindcouncil.com/newsletter/2006-mar.shtml)

If you read the above you will be even angrier.

[nopain]

They only used 400 IU of vitamin D a day - that is way to low to show anything.

How much should they have used?

[rose]

There's a rash of those again lately. I just read a newspaper article reporting that research showed people who do not have heart disease should not take fish oil. And people should stop taking vitamins C, E, and A.

Pharmaceutical companies must be heavily greasing palms in these areas. What disgusting crap.

rose

[Ted Hutchinson]

How much should they have used? Optimal levels are above 50 ng/mL (125 nM/L) so depending on where the person was living and the amount of sunlight available, sufficient D3 to raise status to the optimal level.

Vitamin D: What's Enough? Many people may need much more Janet Raloff (http://www.sciencenews.org/articles/20041016/bob9.asp)writing in 2004 reports Holick says that physicians could measure 25-D in blood and prescribe increasing doses of the vitamin until 80 nmol/l is reached. Such personalized prescriptions could take into account lifestyle and pigmentation. For instance, Heaney's research in Omaha indicates that elderly, dark-skinned women could require up to 2,000 IU of vitamin D to keep 25-D concentrations around 80 nmol/l. So really it depends on where you live and how much you get outside. There are time particularly above latitude 45 where no sunshine is available and many of us live in countries where milk is NOT fortified and so our levels get particularly low during the Winter. In these cases up to 4000iu/d does not seem unreasonable.

The point is that if you only have 10% of the oil in you car engine it will be more likely to have engine problems. If there is only 10% of the required amount of air in you tyres you'll have handling and fuel efficiency problems. Before you start a research project on identifying the benefits of a particular supplement regime you need to identify the current status of the client group, then raise that status by using such an amount as will effectively do the job. Using 10% of the amount the body actually uses daily is such a small drop in the ocean it wouldn't be detectable. All the report is actually telling us is that if you use an insignificant amount of vitamin d the impact on health is not detectable.

If you give a bankrupt a few dollars a day (less than 10% of his daily living expenses) will it solve his bankruptcy scenario?

[annelb]

The Vitamin D council comments on the Womens Health Initiative research project (http://www.vitamindcouncil.com/newsletter/2006-mar.shtml)

If you read the above you will be even angrier.

You are right, Ted. Thanks. The Vitamin D Council is an excellent resourse. I also get the newsletter.

My vitamin D was never checked until I asked about 2 years ago. By taking about 1500 IU a day I have raised my vitamin D from 24 to 42 this fall. I am curious as to what the level is now after winter - I will get a recheck soon.

It is interesting how many health problems seem to escalate in the winter. Anne

[annelb]

Here is a collection of better articles about vitamin D and vascular/heart health http://www.vitamindcouncil.com/researchHeartDisease.shtml and a quiz http://www.vitamindcouncil.com/newsletter/2005-dec.shtml

Amazing that no doctor ever suggest that I have a vitamin D test - I had to insist on it.
Anne

[annelb]

I read a great analogy last night.

This study that used only 400 IU of vitamin D and concludes vitamin D does not help the heart is similar to giving a person, dying of thirst, one glass of water a day and then concluding that water does not help dehydration.

Anne

[nopain]

There is nothing wrong with their study or their conclusions.

They supplemented the RDA amount for women 50 to 71 in addition to whatever other dietary intake they were receiving.

What they concluded was supplementing the normal RDA amount of Vitamin D in addition to the persons normal diet and exposure to sunlight did not benefit the individuals in the study.

What the smart researcher would now do is draw a new hypothesis and find a pool of candidates to do the next study at 800 iu or ?

What the media outlets will report is:

VITAMIN D IS NOT EFFECTIVE FOR HEART HEALTH.

So this studied proved there wasn't much benefit to 400iu. Thats it, nothing more. You can't blame the researchers. Imagine if 400iu had proven to provide great benefit?

Imagine a study where they gave them too much and everyones condition got much worse.

So let this one ride for what it's worth.

The point of my how much should they have used was not to determine an exact amount but to open a dialog. How does a research team determine what amount of a substance (any substance) to test on a pool of live human subjects?

[rose]

There may be no problem with the study, but there is a huge problem with the reporting on it.

rose

[annelb]

It is true, if you read the complete paper, there is mention that the dose of vitamin D may have been inadequate. Possible explanations of this null finding include the
following: (1) Background calcium use impaired our ability
to identify a treatment effect; (2) the dose of vitamin D was
inadequate; (3) poor adherence to study medication blunted
any treatment effect; (4) concurrent postmenopausal hormone
therapy interfered with treatment effects; (5) the trial was
designed to evaluate the effects of calcium/vitamin D supplementation
on fracture, not cardiovascular disease; or (6)
calcium and vitamin D do not, in fact, affect cardiovascular risk.

I did not see vitamin D levels for these study participants. Did I miss that?

Another problem with this study is they used calcium carbonate - calcium citrate is better absorbed from all I have read (and my doctor told me so :rolleyes: )
Anne