Supplements: Healthy or Harmful?

supplements

“I will apply dietetic measures for the benefit of the sick according to my ability and judgment; I will keep them from harm and injustice.”

“In purity and holiness I will guard my life and my art.”

-Excerpts from the Hippocratic Oathe

There is a lot of hype regarding vitamin and mineral supplementation these days, whether it be the next key to longevity multivitamin marketed to you by various supplement manufacturers, or arm-flailing, attention-grabbing warnings found in the media via various editorials often interviewing concerned scientists and medical professionals.  Unfortunately neither side does a very good job at properly informing the public on how to make wise choices for their individual circumstance regarding this matter (because nutrition, as with all forms of science and art alike, is complex). Thus, the outcome inevitably is confusion and frustration.  One week, vitamins are good, life-saving in fact, and the next week they have brought you ever-so-closer to the grave.  Which one is it??

In this post, I will explain why supplements exist, why most people should consider supplementing (this of course means talking it over with your doctor and nutritionist), and are there any potential consequences to vitamin/mineral supplementation (specifically, I will address the recent editorial on over-supplementing with certain vitamins that were found to amplify the growth of various cancers).  I will conclude with my thoughts on supplement safety and regulation in the US as it currently stands.  My main objective is to give you a more comprehensive view of what the peer-reviewed research says about supplementation including its safety and precautions, as opposed to exposing you to just one side of the story.

Let’s start from the beginning:  why supplement at all?

I’m sure this will not be news to most of you, but I feel it is important to mention why supplements even came about.  So we all know vitamins and minerals are vital to life, and throughout time humans have obtained these micronutrients through foods; primarily plants, insects and animals.  We know that the nutrient-density of our plant foods depends on the health of our soil, and historical data has shown that the average mineral content of vegetables grown in US soils has declined abruptly over the last century.  (1) 

Research published in the Journal of the American College of Nutrition in 2004 found significant declines in the mineral and vitamin content of 43 garden crops grown in US markets.  (2)  The authors conclude that this could be due to a “trade-off” between high yield of crops and their nutrient content, while there are  other researchers coming across similar conclusions, adding selective breeding as another possible culprit.  (3)  This is a whole other can of worms that I’ll be sure to dive into more in depth in a future blog post.

So, our soils have been leached of essential nutrients, but is this enough evidence to assume justification for vitamin and mineral supplements?  Well, let’s pair this information with the Standard American Diet of pre-packaged, highly processed “foods”.  I trust I do not need to tell any of you that these foods are very poor in essential vitamins and minerals. If you are reading this blog, chances are you are reading nutrition labels, but I felt it is important to note that this issue is slowly turning into a “lose-lose” when it comes to these very important micronutrients.  We have one end, where people are trying to consume as many vegetables and fruits as they can to get adequate amounts of these vitamins and minerals from foods, but the soil and crops are being impoverished of these nutrients. Then on the other end we have people eating very micronutrient-poor, pre-packaged foods (and not that I’m pointing a shameful finger in their direction, I understand cost and convenience are also factors) but the main issue at hand appears to be this: the American diet, whether rich in fruits and vegetables or pre-packaged foods, is lacking more and more in the nutrition vital to fueling our existence.

And this is not just my humble opinion: Harvard researchers Drs. Robert Fletcher and Kathleen Fairfield convinced the Journal of the American Medical Association (JAMA) to rewrite its guidelines regarding the use of vitamin and mineral supplements. (4), (5)  In two reports published in the June 19, 2002 edition of JAMA, the authors conclude:

“In the absence of specific predisposing conditions, a usual North American diet is sufficient to prevent overt vitamin deficiency diseases such as scurvy, pellagra, and beriberi.  However, insufficient vitamin intake is apparently a cause of chronic diseases.  Recent evidence has shown that suboptimal levels of vitamins, even well above those causing deficiency syndromes, are risk factors for chronic diseases such as cardiovascular disease, cancer, and osteoporosis.  A large proportion of the general population is apparently at increased risk for this reason.”  (4), (5) 

Flash-forward to 2012, where the Journal of the Academy of Nutrition and Dietetics published this review of the National Health and Nutrition Examination Survey (NHANES 2003-2006) examining 8,860 participants over the age of 19. The researchers extracted the following data:  (6)

Image courtesy of J Acad Nutri Diet. 2012 May; 112(5): 657-663. E4 Doi: 10.1016/j.jand.2012.01.026

Image courtesy of J Acad Nutri Diet. 2012 May; 112(5): 657-663. E4
Doi: 10.1016/j.jand.2012.01.026

Those NOT supplementing with anything:

  • 96% inadequate in vitamin D
  • 48% inadequate vitamin C
  • 96% inadequate vitamin E
  • 58% inadequate vitamin A

Those who were supplementing with vitamins and minerals:

  • 25% inadequate vitamin D
  • 3% inadequate vitamin C
  • 5% inadequate vitamin E
  • 2% inadequate vitamin A

But are these supplements safe for everyone?

-This is a broad question, with an even broader answer.  To quote the father of toxicology Paracelsus, “all things are poison and nothing is without poison; only the dose makes a thing not a poison.”  In other words, “the dose makes the poison.”  This gets tricky because not everyone has the same levels of these nutrients in their bloodstream, so a therapeutic dose for one person, may be toxic to another.  This is especially true of fat soluble vitamins, such as vitamin D.  I’m sure most of you are aware of the vast number of health benefits one obtains from vitamin D, but too much (as with anything) can be toxic.  Large doses of supplemental vitamin D can cause improper tissue calcification, which can lead to kidney stones and even calcification of the arteries.  Vitamin K2 prevents against the toxicity of vitamin D, and it is known that vitamin D depletes and increases the need for vitamin K2.  (7)  I see people who take fairly large doses of vitamin D without having blood work done to check their levels.  Bad idea.  Vitamin D testing is so inexpensive now (and covered by insurance if you didn’t want to pay out of pocket), I don’t ever put people on a vitamin D supplement until I know what their levels are.  Granted, I have yet to come across someone who has high levels of vitamin D, but we still have to test: if you’re not assessing, you’re guessing.  Now, when I do see someone with low serum vitamin D, I will put them on a vitamin D3/vitamin K2 supplement (dose depending on their levels).  If you have a healthcare practitioner recommend you take “X” amount of vitamin D3, be sure it also has vitamin K2.

But recent reports are stating that high amounts of vitamins can increase cancer risk.

-This one is interesting, and another prime example of why context is key when evaluating the research.  If you look at the actual study, which was a meta-analysis published in the 2012 Journal of the National Cancer Institute, you can find not only flaws in the studies they reviewed, but also that some media outlets completely misinterpreted the studies actual findings.  Let’s take a look at this meta-analysis and see for ourselves if this applies to us:  (8)

In the abstract they open with how vitamins are used to treat nutrient deficiencies and link to the same NHANES study I linked to above, which also states that half of the population is currently taking a vitamin and mineral supplement.  They imply that these supplements aren’t necessary because nutrient deficiencies (such as scurvy, pellagra, etc.) are fairly uncommon in industrialized countries such as the US.  What they conveniently left out of this opening statement was that nutrient inadequacies do exist in the US and are linked to multiple chronic diseases, and they failed to mention the percentage of inadequacies even in folks who supplement (as previously shown in the graph above).  So right away we have some cherry-picking of data going on, but let’s see what else they have to say.

They also state, multiple times, that supplement sales are estimated to be approximately a $30 billion industry in the US.  They pair those statements with a few studies that question the efficacy of supplements (even though there are plenty of studies refuting those and that actually show efficacy) which generates quite a nice piece very subtly suggesting that supplements are a scam.  By the way, it is interesting to note that pharmaceutical sales are over ten times that of supplement sales ($300+billion industry), but you don’t see me on here cherry-picking research questioning their safety and then concluding that nobody should take pharmaceuticals.  Look, there are unfortunately some ‘bunk’ supplements with very poor quality standards and I will get into that at the end of this post, but it is important to understand that the literature still clearly states that even folks that supplement improve their nutrient status, but still are not obtaining adequate amounts!

First, they cite studies on antioxidants (mostly vitamins A and E) and how they have been shown to not effectively prevent cancer as well as have contributed to accelerating cancer growth!  Now, the studies they linked to share a few common flaws:

  1.  Lack of biochemical analysis of these nutrients at baseline and at the end of the study, and if they did have a nutrient baseline, it wasn’t measured via an analysis of their serum but rather a “supplement questionnaire”. The nice thing is the meta-analysis actually points out this flaw as well, which I appreciate. The media, however, failed to mention it.  Whoops!
  2.  They were often mega-dosing with these nutrients. For instance, in the Beta Carotene and Retinol Efficacy Trial (9) that was linked to in this meta-analysis, participants were exposed to over 8 times the RDA for vitamin A, and for a total of 4 years!!! Not to mention, this study was also conducted on smokers, former smokers, and those exposed to asbestos.  Is this study good enough evidence to tell everyone in the US they may want to reconsider their vitamin and mineral supplement?
  3. Most of the studies involved either people who smoked, or were already chronically ill.  How does mega-dosing individual nutrients in folks already chronically ill relate to disease prevention?  Besides, like disease, nutrition is complex, so for the media to extrapolate vitamins may not work based on studies where they tested vitamins A or E together or by themselves, really doesn’t tell us much.  Especially if the participants were smokers and other confounding factors weren’t measured, such as diet, exercise, sleep, etc.  PLUS, there is evidence to refute it, as I will link to in a bit.
  4.  Most studies used synthetic, alpha tocopherol for the vitamin E supplement. In the Physician’s Health Study II, a randomized, double-blind, placebo-controlled trial on 14,641 men, synthetic vitamin C, synthetic alpha tocopherol (vitamin E) and a synthetic multivitamin (Centrum) were used. (10)

synthetic vs natural vit E

Side-note on vitamin E as alpha tocopherol:  Alpha tocopherol is the most common type of vitamin E used in supplements.  There is a natural form known as d-alpha tocopherol and a synthetic form known as d/l-alpha tocopherol.  The synthetic form does not appear in natural food sources of vitamin E such as leafy green vegetables, red palm oil, avocados, olive or avocado oil and nuts, and high doses of this synthetic form can cause adverse effects-including hemorrhagic toxicity-an effect not reported with natural vitamin E.  Food sources of vitamin E have a combination of various tocopherols and tocotrienols.  This is one vitamin where I do tend to agree with the researchers: try to obtain vitamin E naturally from foods as often as possible.  There has been some interesting research showing that supplementation with alpha tocopherol alone can decrease levels of other important tocopherols such as gamma tocopherol and delta tocopherol.  (11)  So, if you are going to supplement with these nutrients, I do recommend that your vitamin E form should be as “mixed tocopherols”.  I have yet to come across any research suggesting the harm of mixed tocopherols.  Again, the studies in the meta-analysis showing harmful effects of vitamin E supplementation used synthetic forms of alpha tocopherol or alpha tocopherol alone.

Side-note on folate:  The paper also links to conflicting studies regarding folate.  Some, show protective effects against cancer (12) but others suggest once you already have cancer, folate can cause a more rapid progression of these cancer cells.  This is because folate is active in cell proliferation, so if you already have cancer, this can be used against you.  There is also some evidence that shows high levels of methylation (which methyl folate promotes) can over-methylate and potentially “silence” genes that shouldn’t be-such as tumor suppressor genes. (13)  It is also important to note that most of the studies that showed deleterious effects of folate were actually looking at the synthetic form: “folic acid”.  There are numerous studies within this meta-analysis that link folic acid to various cancers.  Some researchers even hypothesize that the excessive consumption of folic acid in fortified foods (such as grains) may be directly related to an increase in cancer rates.  Excess folic acid in our system gets converted to unmetabolized folic acid, which is associated with natural killer cytotoxicity.  (14)  Since natural killer cells play a role in tumor cell destruction, this could be yet another mechanism for why they saw higher cancer incidence with folic acid supplementation.  Also, an estimated 40-60% of the population have what’s known as an MTHFR single-nucleotide polymorphism (SNP for short, think of it as a mutation) that effects their ability to convert folic acid into its activated form, methylfolate.  This is another issue with folic acid, it has to get converted into folate to be active, and if about half the population has issues converting this synthetic nutrient (due to the SNP), then this leads to a build-up of folic acid and thus, unmetabolized folic acid. The MTHFR information is becoming more popular, if you Google it you will find quite a bit of info on the subject.  I will write a post on MTHFR SNPs in the future, because it is a fascinated field of research!  Folate, the natural form of the vitamin, is found abundantly in leafy greens and liver.  I actually urge my clients to stay clear of foods fortified with folic acid and folic acid supplements.  If they’re taking a B-complex or a multivitamin, I have them make sure that the form is L-methylfolate (5MTHF).  Some of you may be asking, “but what about folic acid preventing neural tube defects?”  There is actually some research now suggesting neural tube defects can be a result of a choline deficiency.  (15)  So if you’re taking a prenatal, again make sure it contains methylfolate and not folic acid, and make sure it has choline.  If it doesn’t have choline, make sure you consume at least 5-7 egg yolks per day or you can supplement with sunflower lecithin if you don’t tolerate eggs.

So there is definitely evidence that mega-dosing with individual vitamins and/or synthetic vitamins that are not found in foods may be unwise.  So is there a case for supplementation?  Let’s have a glance at the research that supports supplementation, more specifically regarding cancer, since that is the topic of the study in question:

  • Magnesium: I felt the need to mention this one first, because magnesium is used in over 300 enzymatic processes (16) one of which being DNA repair enzymes. (17) This means magnesium is critical for cancer prevention. Recent research suggests that 48% of the US population is deficient in this essential mineral. (18) Magnesium can be found in the center of chlorophyll molecules, so green, leafy vegetables are a good source of this mineral. Other sources include: halibut, artichoke, cashews, sunflower seeds and almonds. On top of consuming foods high in magnesium, I do like to see most of my clients supplement with it. This is because based on their diet analysis, I often see they are not consuming enough, plus, if you are consuming a pro-inflammatory Standard American Diet, I definitely like to see supplementation. My dose recommendations vary based on the client’s specific circumstance, but the RDA for adult males is 420 mg/day and 320 mg/day for adult females. My favorite forms of magnesium are chelated forms like magnesium glycinate. I also like magnesium citrate, both are shown to have an optimal bioavailability.
  • A 19-year study of colorectal cancer rates found the relative risk in men with poor vitamin D status was almost triple that of men with sufficient vitamin D levels. (19) In a meta-analysis of studies from 1966-2004, researchers concluded that 1,000 IU per day of vitamin D3 or serum levels >33 ng/mL lowers an individual’s risk of developing colorectal cancer by as much as 50%. (20) Again, get your levels checked! It’s cheap and worth it. A 2008 review on vitamin D research concluded that intakes between 1,000-4,000 IU per day offer protection against breast, colon, prostate, ovary, lung, and pancreatic cancer. (21) Now, stop reading this post, hop on to Direct Labs (www.directlabs.com) and place an order to get your vitamin D tested! They will send you a requisition form that you print out and take with you to your nearest LabCorp and you’re good to go! I actually like to see people get both their 25(OH)D tested (standard vitamin D test) as well as their 1,25(OH)D tested but if you had to choose one, just go with the 25(OH)D for now.
  • Eating a choline-deficient diet for as little as one month was shown to lead to increases in DNA damage. (22) Women with high choline intakes had a 24% lower risk of breast cancer. (23) Again, choline-rich foods include egg yolks, beef liver (only consume ¼ lb. per week), sunflower seeds and sunflower lecithin.
  • So we know there are studies suggesting the synthetic form of vitamin E can increase risk for cancer, but conversely, gamma tocopherol has been shown to regulate genes that influence cancerous growth. (24)

The researchers close with a suggestion to look into further regulating dietary supplements.  More specifically, in regards to how they are marketed.  They mention the potential dangers of supplement companies marketing products aimed at cancer treatment, which I completely agree with.  Even if the labels states to “consult with your physician before taking this product”, saying that this product has been shown to be beneficial for cancer can be murky waters, and I agree that those statements should be refrained from being used.  Having said that, I also don’t see claims like that very often anymore, so I’m not sure if that is still an issue?  What do you think?  If you have examples of this, please share in the comments because I am very curious about how prevalent that kind of marketing is in the industry.  Aside from manufacturer’s claims, I do think it is important for companies who have employee’s selling supplements first-hand that they are well-versed with the Dietary Supplement Health and Education Act (DSHEA), to avoid making any direct and potentially harmful claims.  Here is an interesting post I came across that is a nice, quick read for anyone who may be in supplement retail:  (www.m.newhope360.com/supplements/5-dshea-takeaways-natural-retailers )

Speaking of potentially harmful, here are a few statistics I want to share:

  • A meta-analysis published in the Journal of the American Medical Association (JAMA) in 1998 found that 106,000 individuals died due to adverse reactions to pharmaceutical drugs. (25) The paper went on to state that these would be between the fourth and sixth leading cause of death during that time.
  • According to the Centers for Disease Control and Prevention (CDC), nearly 15,000 people die every year due to overdoses of prescription painkillers alone. (26)

I share these because I want to make a point, and that is it is easy to find research supporting a claim and then run with it.  If I left you with these two bullet points, the reader is most likely going to take-away one notion: that pharmaceutical drugs are bad.  When in reality, there have been a few papers published discussing the flaws in the meta-analysis I linked to first published in JAMA 1998, but the second example regarding prescription painkiller overdose is also not enough to make generalizations.  Why?  Because painkillers are known to be addictive, and these deaths were due to consuming too much of this drug, not necessarily due to the drug itself. Remember, “the poison is in the dose.”  Now, can one make the case that perhaps these drugs are being overprescribed? Sure.  But I am not a pharmacist, nor an MD, and I don’t play one on the internet 😉 The reality is health is not black and white, and that is the point I’m trying to make in regards to this supplement scare.  Context.  The media made very poor assertions stemming from one side of the story, so my job is to give you both sides to make more informed decisions.  To give another example, we know that overconsumption of water can lead to a condition known as hyponatremia, which can cause fatally low levels of sodium in the blood.  Subtext:  too much water can kill you.  Do we need to the FDA to step in and regulate water consumption for us?  Of course, this is an absurd proposition, but I mean, there are healthcare professionals also simply stating “drink more water”.  What does that mean?  Should we regulate being able to make that suggestion?  Seems a bit extreme, and what I’m getting at is I’m for anything to improve safety within the lines of rationale, but I just can’t justify “witch hunts”.  So before we call on the FDA, then break out the pitchforks and torches and start marching to bring the pro-supplement camp to justice, we have to ask ourselves: “how many people have supplements been shown to harm per year?”  This is actually quite fascinating:

  • According to the latest Annual Report of the American Association of Poison Control Centers’ National Poison Data System (NPDS 31st edition) published in 2013: ZERO DEATHS DUE TO VITAMIN, MINERAL, AMINO ACID, AND HERBAL SUPPLEMENTS. None. Nada. Goose-egg. (27) Now, I will say studies have shown that mega-dosing with certain nutrients can lead to toxicity over time, I won’t argue with that. But boy is it reassuring to know people aren’t overdosing on supplements. To put this in perspective, more people are dying per year of consuming too much water than supplements.
  • In a recent meta-analysis with a pooled sample of 91,074 people published in the American Journal of Clinical Nutrition looking at multi-vitamin and multi-mineral supplementation and mortality, the researchers not only conclude that “multi-vitamin and multi-mineral treatment has no effect on mortality risk”, but they also found that there was actually a reduced risk of all-cause mortality across primary prevention trials. (28)

I’ve actually put in a good amount of effort trying to find a direct link to vitamin and mineral supplements and increased risk of mortality.  All I can find is the same old mega-dosing with synthetic vitamin E or vitamin A studies, or ones conducted on smokers and chronically ill individuals, but nothing on multi-vitamins, multi-minerals or any other nutrients.  If someone does come across such a study, please share!

I do need to mention that this paper did not get it all wrong: if you already have cancer, or are a smoker, it appears that abstaining from supplementation with vitamin A or vitamin E (at least alpha tocopherol and its synthetic form for sure) is probably a good idea.  A highly oxidative environment caused by someone who excessively smokes can cleave retinoic acid (synthesized from vitamin A) into a by-product that can damage DNA (which leads to cell mutation and cancer). The paper goes on to state how these antioxidants can also prevent apoptosis (cell death) from occurring in cells with damaged DNA (which leads to cancer as well) so you actually want those cells to die.  This is what I was talking about earlier when I said, context is everything.  And since vitamin A supplementation does have such an achievable toxicity, I do typically tell my clients to just obtain vitamin A from foods (such as sweet potatoes, egg yolks, liver, wild salmon, grass-fed butter, pumpkin, butternut squash, carrots, etc.)  This paper does also mention that vitamins and minerals should be obtained through foods whenever possible which I also agree 100% with.  In regards to cancer, consuming more raw cruciferous vegetables such as kale, garlic, onions, cabbage, cauliflower and broccoli, may activate tumor suppressor genes due to compounds they contain known as isothiocyanates. (29) But, as shown at the beginning of this post, often times consuming nutrient-dense foods alone without supplementation isn’t enough to get adequate amounts for a lot of people.  So how do you know which supplements are right for you?  The best, most efficient and safest way is to speak with a healthcare professional first.  I recommend both a licensed or certified nutritionist and of course your doctor.  I do like multi-vitamins but remember, if you smoke you may want to rethink them because of the vitamin A and vitamin E or at least find one with very miniscule amounts of these.

Supplements are just one piece to the puzzle.  I don’t think that just because we don’t have studies showing that isolated vitamins aren’t curing all of our modern diseases that we should ‘throw the baby out with bathwater’ and start scaring people away from vitamin and mineral supplements.  This is not a jab at the meta-analysis, nor the researchers, in fact, this whole post was to show that the media once again took science out of context.  It’s important to include possible drawbacks to over-supplementation, toxicity is real and I do agree it’s important to emphasize caution.  And I am fascinated by possible contraindications of vitamin supplements in the ‘smokers’ population.  I think that is a very important take-away, that none of the mainstream media articles I found even mentioned, yet it was mentioned multiple times throughout this meta-analysis.

So… in conclusion:

  • Should everyone stop taking their multi-vitamin, multi-mineral supplement? No, but you do want to avoid multi-vitamins with too high levels of vitamin A, synthetic forms of vitamin E or only alpha tocopherol (look for mixed tocopherols instead), and folic acid (look for folate, methylfolate, or 5MTHF instead). And, as always, ask your doctor and nutritionist if a multi is right for you.
  • If you smoke, you probably want to stay away from supplements with vitamins A and E. I would definitely ask a healthcare professional about looking into magnesium supplementation (to help repair damaged DNA), as well as incorporating more raw, cruciferous vegetables (due to their ability to activate tumor suppressor genes).
  • In the US, supplement companies are not required to any post-market surveillance program on their product; in fact, the FDA only investigates products after problems are found. Because of this, when buying supplements you should make sure they not only follow Good Manufacturing Practices (GMP compliance), but should also be third-party tested for ingredient identity and potency, personnel, document management, equipment, facilities, component control, maintenance, record keeping, laboratory controls, label controls, quality controls and performance reviews. The USP Dietary Supplement Verification Program (DSVP) and the NSF Dietary Supplements Certification Programs are two very reliable, stringent, and trustworthy third-party testers. Top-quality supplement companies should have frequent audits making sure their products are constantly being verified and compliant with these strict, quality standards. The top supplement companies that hold consistent audits and maintain the highest GMP certification analysis’ are: Douglas Laboratories, Blueberry Health Sciences, USANA Health Sciences, Xymogen and Vital Nutrients. I’m sure there’s even more, these were just ones I came across initially, if I missed any, please share in the comments! I like Xymogen a lot because they are not only third-party tested by two different companies (NSF and IFOS) but also test their products for heavy metals such as lead, mercury, arsenic, cadmium and other contaminants such as solvents, pesticides, PCBs, gluten, etc.) Vital Nutrients also tests for chemical solvents, lead, mercury, cadmium, arsenic, herbicides, pesticides, fungicides, dioxins, PCBs, aflatoxins and fungal toxins.
  • If you really wanted to have a more comprehensive view of what your nutrition status is, you can ask your nutritionist to look into Micronutrient Testing through SpectraCell Laboratories which tests your vitamin, mineral, amino acids, fatty acids and antioxidant status. This way you know for sure which nutrients you are lacking, and which are in the optimal reference range. For more info, check out their page here: www.spectracell.com

I am going to do a series of posts on supplements.  I think my next post regarding this topic is going to dive into the science and uses of herbs and amino acid supplements, so stay tuned.

I would like to hear from you.  Are you for or against supplementation and why?  Is there anything I left out in this post, that you wish I would have touched on?  Leave your thoughts and questions in the comments! 

References:

  1. www.nutritionsecurity.org/PDF/NSI_White%20Paper_Web.pdf
  2. www.ncbi.nlm.nih.gov/m/pubmed/15637215/
  3. www.ncbi.nlm.nih.gov/m/pubmed/19013359/
  4. www.jama.jamanetwork.com/Mobile/article.aspx?articleid=195039
  5. www.jama.jamanetwork.com/Mobile/article.aspx?articleid=195038
  6. www.ncbi.nlm.nih.gov/pmc/articles/PMC3593649/#!po=40.1786
  7. www.ncbi.nlm.nih.gov/pubmed/19022954?dopt=AbstractPlus
  8. www.ncbi.nlm.nih.gov/pmc/articles/PMC3352833/#!po=10.4938
  9. www.ncbi.nlm.nih.gov/m/pubmed/8602180/
  10. www.ncbi.nlm.nih.gov/pmc/articles/PMC2774210/
  11. www.ncbi.nlm.nih.gov/m/pubmed/14519797/
  12. www.ncbi.nlm.nih.gov/m/pubmed/17684216/
  13. www.ncbi.nlm.nih.gov/pmc/articles/PMC1421942/
  14. www.m.jn.nutrition.org/content/136/1/189.short
  15. www.ncbi.nlm.nih.gov/pubmed/19593156?dopt=AbstractPlus
  16. www.nlm.nih.gov/medlineplus/ency/article/002423.htm
  17. www.ncbi.nlm.nih.gov/m/pubmed/11295157/
  18. www.ncbi.nlm.nih.gov/m/pubmed/22364157/
  19. www.ncbi.nlm.nih.gov/m/pubmed/2857364/
  20. www.ncbi.nlm.nih.gov/m/pubmed/16236494/
  21. www.ncbi.nlm.nih.gov/m/pubmed/18034918/
  22. www.ncbi.nlm.nih.gov/pubmed/16825685?dopt=AbstractPlus
  23. www.ncbi.nlm.nih.gov/pubmed/19635752?dopt=AbstractPlus
  24. www.ncbi.nlm.nih.gov/m/pubmed/15753148/
  25. www.ncbi.nlm.nih.gov/m/pubmed/9555760/
  26. www.cdc.gov/vitalsigns/painkilleroverdoses/index.html?mobile=nocontent
  27. www.aapcc.s3.amazonaws.com/pdfs/annual_reports/2013_NPDS_Annual_Report.pdf
  28. www.ncbi.nlm.nih.gov/m/pubmed/23255568/?i=1&from=number%20of%20deaths%20due%20to%20vitamin%20and%20mineral%20supplements
  29. www.ncbi.nlm.nih.gov/pmc/articles/PMC2737735/#!po=8.26087

 

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s