SnakeOil? Scientific evidence for health supplements

Thursday, February 25th, 2010

A generative data-visualisation of all the scientific evidence for popular health supplements by David McCandless and Andy Perkins.

I’m a bit of a health nut. Keeping fit. Streamlining my diet. I plan to live to the age of 150 in fact. But I get frustrated by constant, conflicting reports and studies about health supplements.

Is Vitamin C worth taking or not? Does Echinacea kill colds? Am I missing out not drinking litres of Goji juice, wheatgrass extract and flaxseed oil every day?

In an effort to give myself a quick reference guide, I dove into the scientific evidence and created a visualization for my book. And then worked with the awesome Andy Perkins on a further interactive, generative “living image”.

Play with interactive version | See the still image

This visualisation generates itself from this Google Doc. So when new research comes out, we can quickly update the data and regenerate the image. (How cool is that??) Hopefully then this should be a useful web resources for years to come.

About the image

This image is a “balloon race”. The higher a bubble, the greater the evidence for its effectiveness. But the supplements are only effective for the conditions listed inside the bubble.

You might also see multiple bubbles for certain supps. These is because some supps affect a range of conditions, but the evidence quality varies from condition to condition. For example, there’s strong evidence that Green Tea is good for cholesterol levels. But evidence for its anti-cancer effects is conflicting. In these cases, we give a supp another bubble.

The evidence

We only considered large, human, randomized placebo-controlled trials in our data scrape – wherever possible. No animal trials. No cell studies. Many of the health claims made by the $23 billion supplements industry are based on non-human trials. We wanted to cut through that.

This piece was doggedly researched by myself, and researchers Pearl Doughty-White and Alexia Wdowski. We looked at the abstracts of over 1500 studies on PubMed (run by US National Library Of Medicine) and (which hosts meta-studies of scientific research). It took us several months to seek out the evidence – or lack of.

You can see our key results in this spreadsheet. (It’s the same spreadsheet that generates the interactive image).

Generation Game

This is our first interactive piece here on Information Is Beautiful. We’ll be doing more generative pieces over the next few months so stay tuned!


UPDATE 1: 6th Mar 2010 - We’ve updated the spreadsheet (changes in bold) and the viz after great feedback and new evidence and corrections from our amazing visitors. Thank you all so much.

Quick summary: We’ve added CoQ10, cocoa, capsaicin, L-Lysine and hyaluronic acid to the chart. And adjusted entries for Magnesium, Tumeric and Omega 3 (part of a massive downgrade of Omega 3 in fact). Read the change-log for full details

UPDATE 1: 10th Mar 2010 - Omega 3 has been downgraded in almost every category. See the spreadsheet (changes in bold) for more details.

See the visualisation | Check out the spreadsheet

Feed Us Back

As ever, we welcome your thoughts, crits, comments, corrections, compliments, tweaks, new evidence, missing supps, and general feedback. Thank you!



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Show Comments ( )

  • Tokyo-Jim

    It’s a great visualization, but I cannot find any explanation for how quality of evidence was accessed. The bubble height appears to be driven by Column B in the spreadsheet, but who or what generates that number? Echinacea, for example, links to two abstracts, both of which indicate demonstrated efficacy in clinical trials. I’m not sure why evidence is rated as “conflicting” and below the “worth it” line. An explanation of how this value is derived would aid interpretation of the chart.

    Nice work, I’ve enjoyed your other visualizations as well. (BTW, the link to the echinacea study is broken)

  • Fred

    Why is omega3 listed 3 times below the worth it line and fish oil is listed once above the worth it line? omega3 is in fish oil.

    Great graphic though, keep up the great work!
    thank you

    • Caroline

      He says some supplements might be listed twice as they effectiveness for different conditions varies. For example there is strong evidence that fish oil good for heart disease but not so great for child intelligence.

      Great graph guys!

  • Bobby Baum

    Congratulations – you’ve hit the big time! The latest issue of the scientific journal Nature (Dec. 23/30) includes a figure (page S12) “adapted from“.
    Rosemary (carnosic acid) looks promising (J. Neurochem. 104 1116).
    There is also some evidence that simply eating a more alkaline diet is beneficial (Am. J. Clin. Nutr. 87 662 & references cited).

  • Aaron C. Bennett

    Liver Tablets (Dessicated Liver)

    Erschoff, B(enjamin). H. “Beneficial effect of liver feeding on swimming capacity of rats in cold water.” Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.). July 1, 1951. Volume 77. pp. 488-91.

  • SS

    Very enjoyable viewing. No links to Vitamin A-related evidence in your bubble map. Pubmed has various Cochrane reviews showing little or no evidence for vitamin A supplementation for pregnant or lactating women and their babies in terms of reduced mortality (e.g., but proven effects against nightblindness and anaemia, so you may want to split it into two bubbles.

  • B

    This is great! You might want to take another look at your calcium links, though; the osteoporosis link goes to another paper about colorectal cancer.

  • Hermes
  • Sepp Hasslberger

    A friend asked me how reliable this bubble graph of evidence based supplements was, and I would like to share my reply also with you in the way of feedback. Here is what I said:

    “It seems reliable enough, as it’s based on actual studies. I do see two problems with the information though.

    1) Supplements are treated like medicines, i.e. the only information taken into account are studies that test a single supplement against a specific illness. Normally, this is not like supplements are used. They are nutrients, they act in synergy with each other, and the concept of an “illness” to be treated by a single substance relates to chemical (synthetic) medicines, rather than to nutritive substances. So the picture shown is probably truthful, but it really misses the point of why people use supplements.

    2) To add to this, the line where they say it’s worth taking (their “worth it” line) is drawn WAY too high on the graph. This is a consequence of the mindset of looking at supplements like you would look at a pharmaceutical medicine.

    In medicines, you want to be very sure it is useful, because there are numerous and potentially serious “side effects” (meaning effects of toxicity to some system in the organism) in most medicines.

    In supplements, those considerations are much more relaxed. Being that supplements are nutrients, and mostly quite vital nutrients without which our body cannot make do, the “worth it” line should be MUCH lower on the page. It might well be worth trying a nutrient, even if there is no good scientific evidence of its effectiveness, because of a substantial absence of toxic side effects. You might also want to combine several nutrients for synergistic effect (something that is not measured at all in the bubble graph). The cost is low, and the risk almost negligible.

    So the graph is reliable, as far as it goes, but it applies a measuring method to supplements that fits pharmaceutical medicines much better than it fits nutrient substances.”

    • Phil

      I think your reply is spot on. If a supplement has no side effects, why would the “worth it” line be so high up? It’s like saying something is not worth it even if it might help you with no repercussions. How is that logical?

    • Andy Sutton

      Having been involved in early phase human trials for 30 years I know that your comments and the original graphic are really enlightened as well as attractive and informative.
      I would add that one little-known nutrient that really is worth trying is a filtrate of cows’ milk colostrum because it is safe and not expensive at about a dollar a day. The evidence is a combination of efficacy in one double-blind, placebo-controlled human trial in Alzheimers and in several animal models. (See a review in depth by Szaniszlo P et al. New Insights into a Clinical Trial for Colostrinin™ in Alzheimer’s Disease. The Journal of Nutrition, Health & Aging© Vol 13, Number 3, 2009. p 235-241) . However it’s a great tagedy that research on it completely stalled because of a lack of funds. I review a lot of data on pharmaceuticals and biologicals in development and I don’t remember seeing any other that has such a range of positive effects on the mechanisms underlying Alzheimer’s, so I do think animal models have a useful role. . It’s a contrast with the superficial mode of action of biologicals like antibodies to amyloid plaques which are like treating the rash of meningitis with skin cream.

  • Paddy

    Nice graph! (Although obviously, the usual caveats apply). I’ve four addional suggestions to make, if I may (one a little tongue in cheek):

    “Strong” evidence for the use of zinc supplementation to help treat diarrhoea in children (in addition to the key intervention of oral rehydration solution, or dilute fruit juice with a literal pinch of salt if you’re making your own), as evidenced by this Cochrane review ( and WHO policy (

    “Promising” evidence for Vitamin D supplementation to help treat TB (in addition to the key intervention of the usual anti-TB drugs) as evidenced by a clinical trial published in the latest Lancet (

    “Promising” evidence for Vitamin C to help treat Pneumonia (with similar caveats to the others)

    “Strong” evidence for Vitamin C supplements to prevent or treat scurvy ;)

    @Sepp Hasslberger,

    Unfortunately, there is evidence for harm in some supplements. For instance, fish oil (whose main active agents are Vitamin A, Vitamin D, and a mix of omega-whatever fatty acids) is no longer recommended in pregnancy because it’s a tad too high in Vitamin A (straight Vitamin D supplementation is generally recommended instead). Similarly, as recommended before, high doses of beta-carotene are contraindicated for smokers.

  • Daniel

    Your graphic is very interesting visually, but it suffers from some methodological problems that artificially boost a number of the supplements.

    Dr. Scott Gavura over at Science-Based Medicine, while praising this blog, also brings up a major problem with your presentation. You do not compare the evidence for efficacy versus evidence of harm. If a supplement gives a modest benefit is one area and while also often causing major side effects that would still result it it being recommended. Please look under the section “Information is Beautiful … But Incomplete” at ( Thanks.

  • Amy

    This is a great visualization and thanks so much for doing it. One question: I didn’t see chromium on there. Studies have shown it helps regulate blood sugar in type II diabetics.

  • Mike Paolini

    That is a really cool little flash. Thanks for the share =D

  • Christopher Stelter

    Licorice is listed as helping with coughs, but the research behind it that you link to shows helping with upset stomach. Maybe you should correct the label, especially since this is one of the few “worth it” items?

    (Also, don’t eat excessive amounts of licorice candy if you have hypertension.)

  • Tim McD

    Great site…fascinating to look at the various visualizations. I followed a link from Scott Gavura who blogs on pharmacology at ScienceBasedMedicine (correction to Daniel above, he is not a medical doctor..and I don’t think he’s a PhD either, for whatever that’s worth)

    As a medical doctor with a particular interest in so called Alternative Medicine (SCAM), I am particularly interested in the evidence for the wide variety of supplements, so I was curious to peruse this visualization. On casual review, I think the evidence for efficacy for the majority of these things is over stated. For example, the link on cranberries and UTI cites a journal from 1994 as evidence. That is ancient history in medicine. Mark Crislip, another blogger at SBM and an infectious diseases specialist recently reviewed the evidence, and was far less impressed. It may have a minor role for a small sub-group of patients in preventing a UTI becoming pyelonephritis, but overall not very useful.

  • Daniel

    Really nice visualization …thanks for sharing ;-)

  • Brody

    I love the visualization, at first, I questioned a few placements. Then, I saw the conditions they were for; which explain the triple placement of the Omega 3 fatty acids. I take it that most of the placement is in respect to immediate effects they have on treating a a condition. Because I do agree many of theses supplements/alternative treatments have little to no effect in the short run. Many of the supplements listed are only proven over long term usage in the developmental stages of growth (i.e. Magnesium); in respect to what they prevent and treat.
    So, yeah all you health conscious adults out there need to be careful not to develop toxicity from supplements you may not need to take in the first place.

  • Jim Gerber

    You rank olive leaf pretty high for high blood pressure, but the study you link to was not blinded and did not use a placebo pill in the control group. That’s a pretty poor study that doesn’t fit your stated standards for evidence.

  • Chai

    I find this infographic to be very useful, interesting and important. This is really a great example of how scientific data can and should be made more accessible to the general public.
    Thanks for making it!
    Also, if you could include Black Elderberry based supplements, that would be awesome.

  • Jason Morrison

    Loving this! Really great work.

    I came across this article today:

    Researchers at the University of California, San Diego School of Medicine and Creighton University School of Medicine in Omaha have reported that markedly higher intake of vitamin D is needed to reach blood levels that can prevent or markedly cut the incidence of breast cancer and several other major diseases than had been originally thought. The findings are published February 21 in the journal Anticancer Research While these levels are higher than traditional intakes, they are largely in a range deemed safe for daily use in a December 2010 report from the National Academy of Sciences Institute of Medicine.

  • Jason Morrison

    Also, I get an “Access Denied” from s3 on the changelog txt file.

  • Bobby Baum

    The Feb. 26, 2011 issue of Science News magazine has an interesting article (p. 26) on supplements that boost cognition.

  • Scott Forbes

    Very cool. This is a lot of work and is so simple to use. Thank you very much. Would it be possible to include popular supplements to enhance gains in muscle mass or to prevent sarcopenia? Again, this is amazing.

  • Stephen Van Hook

    Anything on Juice Plus? Is it truly fruits, vegetables that have been dried and have similar effects of the “real thing”? thanks in advance.

  • Bobby Baum

    The March 24 issue of Nature has a very interesting section on cancer prevention that mentions some supplements (p. S22).

  • Me

    OBJECTIVE: To assess the effect, tolerability and acceptability of aged garlic extract as an adjunct treatment to existing antihypertensive medication in patients with treated, but uncontrolled, hypertension.

    DESIGN: A double-blind parallel randomised placebo-controlled trial involving 50 patients whose routine clinical records in general practice documented treated but uncontrolled hypertension. The active treatment group received four capsules of aged garlic extract (960 mg containing 2.4 mg S-allylcysteine) daily for 12 weeks, and the control group received matching placebos. The primary outcome measures were systolic and diastolic blood pressure at baseline, 4, 8 and 12 weeks, and change over time. We also assessed tolerability during the trial and acceptability at 12 weeks.

    RESULTS: In patients with uncontrolled hypertension (SBP ≥ 140 mmHg at baseline), systolic blood pressure was on average 10.2 ± 4.3 mmHg (p=0.03) lower in the garlic group compared with controls over the 12-week treatment period. Changes in blood pressure between the groups were not significant in patients with SBP<140 mmHg at baseline. Aged garlic extract was generally well tolerated and acceptability of trial treatment was high (92%).

    CONCLUSION: Our trial suggests that aged garlic extract is superior to placebo in lowering systolic blood pressure similarly to current first line medications in patients with treated but uncontrolled hypertension.

  • concerned parent

    Why do so many supplements bump up against the “worth it” line? Is a supplement considered worth it only if it is more or less a certainty that it provides benefit?

    If I take 5 “snake oil” supplements and only 1 provides a tangible benefit, I consider that to be worth it. Unfortunately it would be far too much trouble to run a double blind study on myself while controlling for other variables. Regardless, I take approximately 12 supplements daily, justified to myself with a mixture of popularity, available clinical studies, and anecdotal evidence. I doubt if more than 3 or 4 of them do anything.

  • Bobby Baum

    Another article definitely worth reading: “Why Most Published Research Findings Are False”, PLoS Medicine Vol. 2 Issue 8 e124 DOI: 10.1371/journal.pmed.0020124

  • Bobby Baum

    Note that CoQ10 is a form of ubiquinol.

  • Steve

    PubMed study for ubiquinol –

    Study on patients with Type IV CHF and ejection fraction at 22% non-responsive to traditional prescription drugs and CoQ10 changed to ubiquinol (active form of CoQ10) and the mean EF rose to 39% and mean Type to II instead of IV.

  • Tom

    Evidence of protection from the effects of radiation exposure by consumption of resveratrol.

    The Use of 3,5,4′-Tri-O-acetylresveratrol as a Potential Prodrug for Resveratrol Protects Mice from γ-Irradiation-Induced Death
    Currently, no drugs are available to protect humans from γ-irradiation-induced death. Because reactive oxygen species are produced upon exposure to γ-irradiation and directly responsible for the resulting death, we hypothesized that antioxidants found in foodstuffs may provide a safe and potent means of antioxidant-dependent radioprotection. Here, we describe our studies investigating the radioprotective properties of resveratrol and 3,5,4′-tri-O-acetylresveratrol. Each of these natural antioxidants was found to protect live cells after γ-irradiation. In mice, the use of 3,5,4′-tri-O-acetylresveratrol with Cremophor EL was particularly effective, indicating that this natural antioxidant may be a leading candidate for radioprotective drug development.

  • J

    Very interesting. Evidence relating to dementia would be super-useful…

  • Seth Fogarty

    Lovely design, but it would be MUCH more informative if you didn’t have to mouse over for the conditions. They are a central part of the information of the bubble, but we can’t see them at a glance.

  • Carlos Cuello, MD

    Nice job!
    I would use the “x axis” to portray the strength of the recommendation, as evaluated by experts in clinical decision based on evidence and taking into account the harms, costs and possible benefits. We usually use systems to do that, like the GRADE system, which uses four possible areas of recommendations= 1) strong in favor, 2) weak in favor, 3) weak against, and 4) strong against using the substance/intervention. In this way, we could see many interventions that sometimes are recommended for using them even if the evidence is conflicting (i.e., probiotics)
    BTW.- You should ADD PROBIOTICS for preterm babies in the prevention of necrotising enterocolitis

  • Jessica

    I’d like to have a way to ignore popularity, so all the bubbles are the same size. While that’s an interesting piece of information, if I’m actually trying to figure out what I should be taking, I don’t want to be influenced by this piece of information. It’d be easier to focus on the other dimension, position, if bubble size weren’t muddling things up.

  • DrC

    What’s the x-axis?

    • miriam

      Hi DrC,

      Thanks for your comment. The supplements are simply organised alphabetically along the x-axis.

  • Mike

    Vitamin B12 has been studied as an effective treatment for canker sores. (The Journal of the American Board of Family Medicine 22 (1): 9-16 (2009) ) (references a 1978 study in the Journal of Oral Pathology connecting B12 deficiency with canker sores)

  • Lee Mcavoy

    Hi a new goverment directive is being initiated this year making it impossible to sell meny natural herbal preperations on the internet, this is really frustrating for consumers as well as bussiness as their is strong evience to suggest many of these products that contain these ingredients may benefit some health conditions. It seems the reason why this has been initiated (in my opinion is for the benefit of pharma companies).<a href=""

    Didnt see any data regarding flax hull lignanas <a href="; Just the hulls from the seed, Numerous studies suggesting they may prevent the development of breast, prostate, colon & other cancers.

  • Carolorenge

    I must say, what you guys do on this site is awesome, but this snake-oil analysis kinda baffles me a little.
    Sorry, but am not a big fan of snakes either so I’ll probably have to stick to my dogs for now.
    Hey is there any analysis on dogs? It will be interesting to know.

  • Lex

    Your data is fascinating but I think ultimately presents a confusing picture: Certain supplements have been the focus of much attention – not necessarily due to their potential for effectiveness, but due to the potential for profit. So the number / focus of studies appearing on pubmed doesn’t necessarily give an accurate presentation of the supplement’s potential.

    Also I should mention that if you want to “cut through” non human trials (why?), you might give a tip of the hat to the thousands of years of human trials of herbs before the supplements and pharmaceuticals industries started.

    Why not do a follow up by a) doing a graph for the in vivo and in vitro studies and b) an assessment of data from old pharmacopoeia?

    Or better still, a comparison of the proportion of reports of negative side effects for pharmaceuticals vs. the proportion of reports of negative side effects for supplements.

    Infinitely more work, but perhaps infinitely more valuable given the current bias against even the best minds of ancient times…. I would love to see what proportion of the old folklore surrounding herb use turned out to have some basis in fact. A large amount, I would imagine.

  • Joan

    I don’t see any explanation for the size of the bubble. Larger study? Higher quality study? Stronger evidence? Or did I miss reading something?

  • Robbie Mackay

    Looks great. But really hard to tell what condition each supplement is for since many don’t have a condition inside their bubble – really important given most of these are claimed to treat multiple conditions.

    • Alex, Editor

      Hi Robbie,

      If you click through to the full image, you can hover your cursor on each bubble to see which conditions each supplement is for.
      Give it a second and the labels should show.
      If there are any specifically missing, let us know and we’ll check the graphic.


  • Aaron Slepkov

    I was very surprised to see Calcium missing under (low efficacy for) osteoperosis. Is this not the most widely taken supplement for the last few decades? I did then find it in the Google docs but I can’t seem to find it on the chart! It may be there nice and clear, but my XY chromosome is acting up and I can’t find it right in front of me. Is there a supplement for THAT?!



  • Rachel

    I would double-check some of these…Don’t get me wrong; I love naturopathic medicine. However, many studies–in both the allopathic and naturopathic world–are unfortunately ill-conceived and statistically ill-supported, though the data seems there at first glance. Vitamin D deficiency, for example, has been shown to be incredibly overestimated by the medical community. (See for the NIH’s review of the literature.) In fact, if you eat normally and healthily you should achieve appropriate levels of all vitamins without the need for supplementation ( The only people who should supplement their diet with vitamins (and then only B vitamins!) are women who plan on getting pregnant, since folic acid is necessary for fetal development before you can even test positive for hCG.

  • Christian Loiborg

    Hi David,

    I’ve just discovered this great interactive infographic. I’ve read through all of the coments, and although the majority of commenters focus on the information itself, few are also curious as to how you made this. It seems like a flash file is using the data you have entered in the Google Docs-spreadsheet.

    Is the flash file something you have coded yourself or is it a tool available somewhere? I haven’t been able to find that function in Google Docs, and it seems like it is a tad more advanced than what is possible with the standard Google Docs-elements (which are, to my knowledge, based on HTML5 and not flash).

    Perhaps you could offer a quick tutorial to all of us dataloving people who wants to share knowledge in a beautiful way like you do :-)

    - I btw found this via