Evropi Theodoratou, Ioanna Tzoulaki,Lina Zgaga, John P A Ioannidis. Vitamin D and multiple health outcomes: umbrella review of systematic reviews and meta-analyses of observational studies and randomised trials. BMJ 2014;348:g2035
Objective To evaluate the breadth, validity, and presence of biases of the associations of vitamin D with diverse outcomes.
Design Umbrella review of the evidence across systematic reviews and meta-analyses of observational studies of plasma 25-hydroxyvitamin D or 1,25-dihydroxyvitamin D concentrations and randomised controlled trials of vitamin D supplementation.
Data sources Medline, Embase, and screening of citations and references.
Eligibility criteria Three types of studies were eligible for the umbrella review: systematic reviews and meta-analyses that examined observational associations between circulating vitamin D concentrations and any clinical outcome; and meta-analyses of randomised controlled trials assessing supplementation with vitamin D or active compounds (both established and newer compounds of vitamin D).
Results 107 systematic literature reviews and 74 meta-analyses of observational studies of plasma vitamin D concentrations and 87 meta-analyses of randomised controlled trials of vitamin D supplementation were identified. The relation between vitamin D and 137 outcomes has been explored, covering a wide range of skeletal, malignant, cardiovascular, autoimmune, infectious, metabolic, and other diseases. Ten outcomes were examined by both meta-analyses of observational studies and meta-analyses of randomised controlled trials, but the direction of the effect and level of statistical significance was concordant only for birth weight (maternal vitamin D status or supplementation). On the basis of the available evidence, an association between vitamin D concentrations and birth weight, dental caries in children, maternal vitamin D concentrations at term, and parathyroid hormone concentrations in patients with chronic kidney disease requiring dialysis is probable, but further studies and better designed trials are needed to draw firmer conclusions. In contrast to previous reports, evidence does not support the argument that vitamin D only supplementation increases bone mineral density or reduces the risk of fractures or falls in older people.
Conclusions Despite a few hundred systematic reviews and meta-analyses, highly convincing evidence of a clear role of vitamin D does not exist for any outcome, but associations with a selection of outcomes are probable.
I fight this battle every day Brennan, not only with my patients but with colleagues. To listen to the media and even many corners of the medical community one would think its a a well established principal that we should measure vit D levels and supplement them to the normal range with the expectation that we may reap all manner of beneficial effects.
The fact is that some associations have been demonstrated but no causal links have been established between vit D supplementation and reduced illness. Furthermore it has not been shown that measuring vit D levels and then supplementing patients until their level is within the “normal range” is either safe or beneficial in the short range or the long term where some vitamins have been shown to increase cancer risks.
The media and my colleagues need to put the brakes on this fad until we know more.
So until we know more it could be possible that we don’t need Vitamin D at all?
Not to go round and round again but that’s not really what we’re saying. What we’re saying is that we don’t know if taking additional amounts above what is in our diet is either safe or beneficial based on the existing evidence. As with all drugs, if there is no clear safety and efficacy data they probably shouldn’t be used until we know more.
Interesting. At one time was thought Tylonal was safe, until people started taking large amounts (ie Nicholette Larson) and dying from liver damage, then warning labels were put on everything that contained acetaminophen, stating that we shouldn’t take several meds containing the drug. I think safety and efficacy applies with all drugs whether they are considered “safe” or not, because large quantities of any medication or supplement is dangerous. Even Advil could be dangerous if you get too much or mix drugs that contain Ibuprofen. So I think, macgyver, you may want to rephrase what you said, slightly, because “additional amounts” of any drug is not safe and there is no efficacy for “additional amounts” of many drugs. Celebrex, an arthritis medication, even has it’s problems and entirely safe. Codeine is safe, IF taken as your dr Rx it, but can be addictive too. So there are dangers with all drugs.
What we’re saying is that we don’t know if taking additional amounts above what is in our diet is either safe or beneficial based on the existing evidence.
As an online Doctor here, are you recommending people cease taking vitamin D supplements?
Are you recommending that people stop taking any and all supplements until “further evidence” can satisfy you and
McKenzie regarding their “efficacy”?
As with all drugs, if there is no clear safety and efficacy data they probably shouldn’t be used until we know more.
The FDA does NOT classify vitamin supplements as drugs. As an online doctor here, are you saying supplements are drugs?
Finally, please explain why everyone should believe you and McKenzie. What if their doctor prescribed a certain supplement for them?
What if you are scaring them off of their prescribed and necessary treatments?
Are you saying that you know more than most doctors?
What you and McKenzie are saying: ”we don’t know if taking additional amounts above what is in our diet is either safe or beneficial based on the existing evidence.”
You don’t know?!?!?! You don’t know either way?!?!
So then why the heck are you coming on here giving people medical advice if you don’t know?!?! Is that safe?
People are supposed to just heed your medical recommendations over other studies and findings because you have a bone to pick
with the Supplement Industry?!?!
The kicker is we have a frickin’ Animal Doctor giving advice here too!
Vyazma I am not an online doctor. I am a real life doctor who is happy to discuss the scientific evidence here for those who are interested. I believe the same is true for Mckenizie. We both have extensive training in science, medicine, and experience interpreting medical literature. Your comment about mckenzie being an animal doctor is obviously meant to be derogatory but comes off just making you sound foolish. For what its worth when I was applying to med school it was actually more difficult to get into vet school. Mackenzie’s grasp of the medical literature is at least as good as mine so you should give him the respect he has earned and deserves.
Getting to more factual issues, the FDA’s classification of vitamins as supplements has to do with regulatory issues rather than biology and medicine. It does not change the fact that they ARE drugs. Anything you put into your body which alters the biochemistry of the body by inhibiting or promoting biochemical pathways or altering cell or organ system function is a drug whether it is commonly referred to that way or not. There is absolutely no question that vitamins are drugs. From a practical standpoint this definition is the only one that matters. Anything which affects the bodies biochemical pathways may have both beneficial effects as well as unintended side effects. This has been well established to be the case with vitamins and supplements just as it is the case with all drugs. It may make you uncomfortable to think of them as drugs but that’s what they are.
I never said no one should take supplements. We have gone over this before, there are cases where supplements may be advisable but for MOST people that is not the case. I am also not advising people to do anything. I don’t give medical advice here. As I said, I am happy to discuss the science and I can tell you what I and the medical community generally recommend to patients but as I do not have a doctor patient relationship with anyone on here I have never suggested to anyone that this was meant as personal advice for them to follow. If your doctor told you to do something different you should follow their advice since they know your specific conditions and I don’t. The things I discuss here are for informational purposes only and they may serve as food for thought to discuss with your own doctor but that’s all.
Let me make one other thing clear. I am not asking people to “heed (my) medical recommendations over other studies and findings “. I am asking people to question the advice of less knowledgeable individuals who are making these recommendations exactly because the studies and findings as you put it DON’T support the notion that taking vitamin D supplements is beneficial. If you read the metaanalysis that Mckenzie quoted above it pretty clearly says just that. Not only do we not know whether vitamin D supplementation is safe or effective, the fact is NO ONE knows, and that is the point. Since no one knows then no one should be advising people do take these supplements without a good reason especially people in the supplement industry, media personalities, or celebrities who know even less.
If we don’t know whether a drug is beneficial and we don’t know if its harmful then we shouldn’t be advising people to take it. Its as simple as that.
But that still doesn’t matter, The FDA says supplements are NOT drugs.
Perhaps you will show me where the FDA says that supplements and vitamins are not a drug first. Even if there is such a statement it does not affect the medical definition of a what a drug is. Aspirin is not suddenly “just a supplement” because you obtain it by sucking on bark form a willow tree instead of getting it from a bottle, and vitamins are not suddenly not a drug simply because someone decides to classify it as something else. Anyone who states that Vit D is not a drug would in fact be wrong. If there is a statement form the FDA stating that supplements are not drugs they are using the definition just in a regulatory manner. The FDA is required to treat items designated as supplements differently not because science says they are different but because An ignorant senator from Utah managed to push a law through congress in 1994 creating an artificial distinction between supplements and other pharmaceuticals. The distinction is entirely artificial and unscientific and was opposed very strongly by the FDA. However as a government agency they are required to follow the law no matter how wrong it is.
MacGeyver, how about you do me a favor an explain why the human body needs Vitamin D?
I don’t have time to give you an education in vitamin D metabolism here nor is it relevant to the point. No one here said the human body doesn’t need vitamin D. What I said is that there is no current evidence that Vitamin D supplements are beneficial or necessary for most people to take. They could be helpful, harmful, or harmless. The fact is that no one knows at this point and anyone who says they do is misinformed.
Dose is always relevant to safety, not just for drugs. Your can die from ingesting too much water or breathing too high a concentration of oxygen. Nothing is perfectly safe, and almost nothing is absolutely toxic. It’s almost always about the dose.
What a totally childish response. You really don’t care about this issue at all do you? All you seem to care about is that no one tells you what to do.
I didn’t give you any advice, and I never asked you to take my word for anything. I simply posted the published reviews of the scientific evidence and offered my opinion on them. Why you need to have a tantrum every time I do is beyond me, but the evidence is here for anyone to look at and draw their own conclusions. They don’t need to take macgyver’s word for what it means, whether he’s an MD or not. They don’t need to believe my interpretation, whether or not I’m really an “Animal Doctor.” And they don’t need to blindly follow your opinion, whether you have a Nobel Prize or absolutely no medical education or credentials at all. See, aren’t we all nice and free to think and do as we please? So what’s the beef?
And as a medically ignorant retired biochemist, I’ll quietly continue taking my 3000 i.u. of vitamin D daily as long as my mind and body are functioning well. I figure that if it hasn’t killed me yet (at 83.5) it can’t be TO harmful.
3000 I.U. daily? That’s an awfully high dose, Occam. I’m not at all against taking supplements, but I believe in taking them within reason. I do 1000 I.U./day in the winter, unless I eat mushrooms or something else high in D, but once the weather gets warmer and I’m in the sun more, I quit, instead of skipping taking it. I’ve done this for the last 3 winters, since I got pneumonia and haven’t suffered a severe respiratory infection since, but I know better than to over do it. 3000 I.U., I think is way over doing it. More than over doing it and potentially dangerous, esp if you also take that much during warmer weather, because you get vitamin D from the sun. That said, 3000 I.U./day and the vitamin D you get from the sun, could potentially exceed human tolerance. Not saying you won’t see 100 doing that, but depending on how many years you’ve been doing that, you might not see 100. There’s moderation, common sense, reason, and knowledge about supplements and then there is total unreason and lack of knowledge. Occam, what you’re doing, esp since vitamin D is stored in fat cells, is bordering on risking not living to being 100 y.o. I don’t think you’re doing yourself any favours taking that much every day, year around. I’d be very interested in looking at your diet to see how much you are actually ingesting every day, esp since you’re not a vegetarian. If you were a vegetarian or even vegan, I’d still say you’d need to cut that dose by a third at least.