Anyone publicly writing about issues of science and medicine from a pro-science perspective likely gets many e-mails similar to the ones I see every week. Here’s just one recent example:

Im sorry the medical community has become decadent and lazy as most that follow your stance could care less to study the real truth. I have also seen it much more deviant as many professionals know the risks and harm vaccination cause but continue to push it through there practices because of pure greed. Many are also scared of loosing there practices for not following the corrupt industry. Im sorry but the medical industry has become drug pushing decadent slobs that only care about there bottom line.

The e-mailer clearly has a particular narrative that he is following (in addition to the amusingly common poor grammar and spelling). He even writes at one point in our exchange, “the details really don’t matter at this point what matters is what the bigger picture…” He is certain of his big picture conspiracy narrative. The details are unimportant.

Being on the receiving end of an almost constant barrage of such medical conspiracy theories it might seem that such beliefs are extremely common. Of course, such e-mails are self-selective and therefore not representative of the general population. I was therefore interested to see a published survey polling the general population about such beliefs. The survey is published in JAMA Internal Medicine, authored by Eric Oliver and Thomas Wood.

Here are the six survey questions and the percentage who agree or disagree (the rest indicating that they do not know).

The Food and Drug Administration is deliberately preventing the public from getting natural cures for cancer and other diseases because of pressure from drug companies. (37% agree, 32% disagree)

Health officials know that cell phones cause cancer but are doing nothing to stop it because large corporations won’t let them. (20% agree, 40% disagree)

The CIA deliberately infected large numbers of African Americans with HIV under the guise of a hepatitis inoculation program. (12% agree, 51% disagree)

The global dissemination of genetically modified foods by Monsanto Inc is part of a secret program, called Agenda 21, launched by the Rockefeller and Ford foundations to shrink the world’s population. (12% agree, 42% disagree)

Doctors and the government still want to vaccinate children even though they know these vaccines cause autism and other psychological disorders. (20% agree, 44% disagree)

Public water fluoridation is really just a secret way for chemical companies to dump the dangerous byproducts of phosphate mines into the environment. (12% agree, 46% disagree)

The numbers are not surprising, in fact I would have guessed they were a bit higher, but again that perception is likely distorted by my e-mail inbox. They found that 49% of Americans agreed with at least one conspiracy, and 18% agreed with three or more. This is in line with the level of belief in non-medical conspiracies. They did not publish, but I would be interested, in the percentage of people who said they disagreed with all of the conspiracies. Many of the respondents indicated that they did not know if a particular conspiracy were true, likely because they had not heard of it before, but were unwilling to disagree on plausibility grounds alone.

An earlier study by Oliver and Wood found similar percentages for political conspiracies. In that study they concluded that belief in conspiracy theories does not track with any particular ideological belief, but rather with a, “willingness to believe in other unseen, intentional forces and an attraction to Manichean narratives.”

This would seem to be true for the 18% who believe in three or more medical conspiracies – they have a tendency to believe in conspiracies. For those who believe in only one or two conspiracies, that might have less to do with personality and more to do with culture and ideological beliefs.

The second part of their study is perhaps more interesting. They found a strong predictive correlation between belief in the above conspiracies and a host of medical behaviors. Conspiracy believers were more likely to use herbal supplements, use alternative medicine, and eat organic food, and less likely to vaccinate, use sunscreen, and have regular physicals.

The largest effect sizes were for taking herbal supplements, which went from 13% for zero conspiracy beliefs to 35% for three or more. Buying from local farms was similar, going from 14% to 37% respectively, while using sunscreen only decreased from 38% to 30% respectively.

I would have been interested in seeing other responses, such as the percentage who visit a naturopath or chiropractor. I would predict that more hard-core use of clearly “alternative” practices (more than just taking supplements) would be a strong predictor of belief in medical conspiracies. This is based upon the observation (documented in many of the articles here on SBM) that much CAM promotion is intimately tied with medical conspiracy thinking. Anti-vaccine sites, for example, often promote homeopathy and other alternatives to vaccinations. Mike Adams of naturalnews is perhaps the most dramatic example of the convergence of CAM and all manner of conspiracy theories.


This survey by Oliver and Wood indicates that belief in medical conspiracies is fairly common, and that such beliefs are not benign, but correlate negatively with important medical behaviors. It’s difficult to tease out cause and effect, and this survey makes no attempt to do so. It’s possible that the same personality profile is attracted to both conspiracy theories and alternative medical practices. It’s also possible that the CAM subculture encourages belief in conspiracy theories, and that the conspiracy subculture encourages rejection of mainstream medicine and acceptance of fringe ideas. I think all of these factors conspire together to create the effect we are seeing in this survey.

The medical community would be well-served if they understood the phenomenon of medical conspiracies. In fact, it can be viewed and addressed as a public health issue. Medical institutions can take such beliefs more seriously, rather than just dismissing them as fringe. Efforts to educate the public about critical thinking, scientific methodology, and how the institutions of medicine work and are regulated, might reduce the popularity of such conspiracy theories.

I also think we need to have as much transparency as possible in scientific and regulatory processes. Secrecy or even opaqueness tends to breed paranoia.

This data (if I may indulge in a little self-promotion) also highlights the importance of efforts such as science-based medicine, the goal of which is to popularize understanding of the science of medicine, and taking a critical view of popular misconceptions, including medical conspiracy theories. I would argue academic and medical institutions to take such efforts more seriously.

Posted by Steven Novella

Founder and currently Executive Editor of Science-Based Medicine Steven Novella, MD is an academic clinical neurologist at the Yale University School of Medicine. He is also the host and producer of the popular weekly science podcast, The Skeptics’ Guide to the Universe, and the author of the NeuroLogicaBlog, a daily blog that covers news and issues in neuroscience, but also general science, scientific skepticism, philosophy of science, critical thinking, and the intersection of science with the media and society. Dr. Novella also has produced two courses with The Great Courses, and published a book on critical thinking - also called The Skeptics Guide to the Universe.