Prevention—science vs. nonsense

There are many ways in which cult medicine believers try to insinuate themselves into the health care system.  As Dr. Gorski has pointed out, “prevention” is one of their metaphorical feet in the door.  The cult medicine literature often says things like, “mainstream medicine is fine for treating acute illness, but what we do is prevention.” What they often leave out is the question of what “prevention” means, what the data on prevention is, and how to properly approach prevention.  It’s likely that one of my co-editors will touch on this topic in a bit more detail, but let me give you an introduction to the topic of prevention.


Prevention is usually divided into three types: primary, secondary, and tertiary.

Primary prevention  refers to the prevention of diseases and conditions before their biological onset.  Examples of our most successful primary prevention interventions are clean water/sewerage and, ironically, vaccination.  I say “ironically” of course because so many of the altmed folks who talk about prevention are anti-vaccine.

Secondary prevention refers to the search for diseases that have not yet progressed to the point of causing overt disease, and intervening to prevent overt disease.  This  includes things like Pap smears, which look for early cervical cancers (which could have been primarily prevented by vaccination), mammography, which looks for early breast tumors,  and colonoscopy, which looks for early colonic neoplasms.  Secondary prevention is sometimes used synonymously with “screening”.

Tertiary prevention refers to the prevention of progression of and complications from existing disease.  For example, retinal and foot exams in diabetics prevent blindness and amputation very effectively.


We know quite a bit about prevention.  As I mentioned, vaccination is a very powerful tool of primary prevention.  Let’s take another example, coronary heart disease (CHD).  We know quite a bit about primary and secondary prevention of this disease, one of the top two killers of Americans.  For example, quitting smoking drastically reduces a person’s chances of developing CHD.  Controlling blood pressure and cholesterol also drastically reduces the risk of developing CHD.  Physical activity and a lower calorie and lower sodium diet lower the risk of developing CHD, although using it as a sole intervention is not always adequate.

Secondary prevention is another area where science has taught us a lot.  We have excellent data on the benefit of certain drugs and certain blood pressure and cholesterol parameters in preventing progression of CHD.  Statin drugs used to lower cholesterol have been shown consistently to significantly lower the risk of cardiovascular events. We are getting quite good at this type of secondary prevention.  So-called lifestyle changes also play a role, but the size of their effect is likely much less than that of medical intervention.  Still, the two used together can be very effective.   Much of the data on lifestyle modification alone are from very small studies, and the data are not nearly as strong as that for quitting smoking, controlling cholesterol, or controlling blood pressure.

Tertiary prevention has been very successful.  For example, diabetics have a very high rate of lower extremity amputations.  Simple foot care programs can prevent most of these.


The alternative medicine community gives a lot of lip service to “lifestyle changes” and prevention, but data from them is very hard to come by.  For example, the U.S. Preventative Services Task Force has dozens of evidence-based recommendations on prevention. The National Center for Preventative and Alternative Medicine (NCCAM) has a page on cancer prevention, but most of it is about studies that have not yet been done, or interventions that have been unsuccessful.

The study of prevention is a science—we can’t just make it up as we go along.  When we give people recommendations on preventing disease, we better know what we’re talking about.  For example, beta-carotenes where thought to have anti-oxidant–and therefore positive–health properties.  It turns out that beta-carotene supplementation may actually increase the risk of some cancers.

When someone talks about prevention, making pretty-sounding promises isn’t enough.  They better make sure they have the data to back it up, or they may end up killing people.

Posted in: Public Health, Science and Medicine

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11 thoughts on “Prevention—science vs. nonsense

  1. jonny_eh says:

    We discussed this very idea on our podcast.

    I thought science did a great job preventing problems with measures like vaccination, statins, and fluoride supplementation.

    These forms of disease prevention also happen to be attacked vociferously by the alt med crowd. Coincidence?

  2. Harriet Hall says:

    I submit that we are not speaking the same language. Scientists have very specific, well-defined concepts of prevention at various levels. When CAM believers talk about prevention, they often have some nebulous idea that if we would just live right we could achieve perfect health and would never get sick. They don’t have to back recommendations up with good science, because we just “know” some things are good for you. There are moral overtones and an idealistic dis-connect from real world practicalities. Scientific medicine wouldn’t have to worry about treating diseases if it would only buckle down and prevent them from ever occurring in the first place. That’s where the misconception starts about medicine “only treating the symptoms, not the cause.”

    What CAM does is “try” to prevent disease with untested recommendations; what they have not done is show that they “can” prevent disease with these measures. And if they can, it will be scientific medicine and no longer alternative.

    Prevention belongs to scientific medicine; they can’t take it away from us no matter what they say.

  3. DevoutCatalyst says:

    Harriet wrote: “There are moral overtones…”

    I remember reading the sales tract for a brand of sea salt at the local woo food shop, which said if you didn’t eat their particular salt you would soon die. There are fire and brimstone-like messages from the world of CAM, people predicting your imminent destruction if you don’t bend to their will and repent of your ignorant ways. Gimme dat old time religion, sister.

  4. Jurjen S. says:

    Quitting smoking isn’t a “lifestyle change”?

  5. Michael says:

    My lifestyle change might be to quit reading this blog, because it is causing hypertension for this reader. I want to live in a world where CAM nutjobs don’t exist.

  6. Dr Benway says:

    Fasten your seatbelt, Michael. This is a trillion dollar fight.

  7. CarolynS says:

    This whole ideology of “rightful living” as the answer to preventing disease is also behind a lot of the efforts to deal with obesity prevention, sodas out of schools and similar efforts. I am not saying that I think soda should be sold in schools one way or the other, but just that this general approach is being oversold fantastically relative to any actual data on its effectiveness, either in changing children or adult body weight or in preventing or warding off disease illness or death. Myths abound. A highly speculative commentary in NEJM a few years ago suggested as a remote possibility that obesity in children might lead to reduced life expectancy in the current generation of children relative to their parents. There were no data presented and this was clearly a speculative suggestion. Yet only a few years later, the head of the RWJ foundation is repeating this speculation as though it were a proven fact. I see this as a slippery slope. We start with perfectly reasonable recommendations to eat, say, fruits and vegetables because this is a prudent diet, but slide downhill to the idea that a main cause of chronic disease is not eating fruits and vegetables and that chronic disease can be prevented in the population by eating fruits and vegetables. Pretty soon we don’t need any medical care at all, just trips to the farmer’s market, to ward off cancer and cardiovascular disease.

  8. naprapath says:

    QUOTE: “The alternative medicine community gives a lot of lip service to “lifestyle changes” and prevention, but data from them is very hard to come by”

    Did you consider the fact that the alternative community has no where near the massive financial backing with which the allopathic medical community has in order to fund these important studies? Believe me, many, if not most CAM practitioners can barely pay their daily bills and we cannot afford to pay for studies out of pocket. We do not have the grant-writing machinery or the facilities which your community possesses.

    In case you didn’t know, much of the information with which the “alternative” community utilizes in our practices are based on studies done by the “allopathic” science community. For example, the efficacy of using Niacin for hypercholesterolemia rather than treating with statins in order to minimize the significant side-effects and then additionally encouraging a lifestyle of exercise and changing maladaptive eating habits as an effective strategy.

    It seems to me like the comments on this entire site is based in fear of the “alternative” community. But please ask yourselves why so many millions are going towards alternative health? Think hard – because you are losing millions of dollars every day! If we worked together to give the patients the best care it would benefit everyone, including lowering health care costs – which we all eventually pay in the end.

    It is my belief that your community could be supporting portions of our community to root out the ineffective practices that have little or no validity but also help promote the ones that actually have beneficial outcomes in them – but to know the difference is not very clear when you suppress or belittle the entire CAM population wholesale.

    Science is always discovering new cures and new strategies to help a person heal and become healthy. Why not open your eyes and encourage helping out everyone by promoting studies of these alternative practices rather than witch-hunt. This way we can truly see which “alternative” practices actually work and which do not – though I suppose they no longer would be considered “alternative” if the allopathic community embraced them!

    For my own little (“alternative”) practice, I go to the medical library all the time to seek the latest and best evidence-based ways to treat musculoskeletal conditions at Northwestern Memorial Hospital. I attend as many seminars as possible – including allopathic-based workshops. I work in tandem with a physiatrist and a physical therapist and we do a comprehensive treatment including strength training, modalities (ultrasound/LLLT/etc), body work/manual manipulation (not chiropractic), stress management training and focused lifestyle/diet education for musculoskeletal conditions.

    Our patients LOVE our treatments and get better quicker than most – but I cannot “prove” that as no money for funding – it is based on observation from the physiatrist and physical therapist from their experiences.

    As a Naprapath, hardly anyone knows who we are or what we do – but we are a basic nuts-and-bolts body work/manual medicine profession which has been around as long as the Osteopathic profession. Our profession does not have the political power or financial backing that your profession enjoys – but believe me, it is not voodoo and our patients get better faster than just taking a pill or just standard in-and-out P.T. – maybe because of the additional attention we give them.

    I am sure most of you will belittle this posting, but sometimes you need to see things in a different light instead of staid old ideas.

    PS – By the way, CarolynS: no one I know who promotes a good diet says that eating a good diet will prevent all disease – but it is true that eating a poor diet may have a systemic effect: obesity, high cholesterol, etc… so not sure why you are concerned that people promoting a good diet is “oversold”?

  9. Joe says:

    My goodness, after all these years- a quack (naprapath) that is new to me! The mind boggles.

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