Medical/Scientific Conventional Wisdom That Turned Out to be Wrong:

For a paper I'm working on, I'm collecting recent examples of conventional wisdom among health professionals that turned out to be wrong once the issue was studied in more depth. I'm not looking for eccentricities, but for generally accepted theories that had a reasonable basis, but have since been refuted or at least strongly challenged. Recent examples I can think of: (1) that it's generally good to give estrogen to post-menopausal women; (2) that being overweight, but not obese, lowers one's life expectancy; (3) that eating lots of fiber reduces the risk of colon cancer; (4) that eating tomatoes lowers the risk of prostate cancer. More examples, along with citations to any relevant scientific studies (including for the examples above), would be most appreciated. Wisdom from commentors regarding how unproven theories become conventional wisdom in the absence of hard data would also be welcome.

Waldensian (mail):
True, it's mostly a story repeated by nutritionists and other non-MDs -- but you might consider the bit about how everyone has to drink eight glasses of water a day. I'm amazed at how many highly educated people believe that.
7.5.2006 7:58pm
Professor Bernstein, please disclose any personal, financial interest you may have in the concept of conventional wisdom turning out to be wrong.

I kid, I kid.
7.5.2006 8:04pm
Mahan Atma (mail):
Might I ask how you plan to discern:

1) What is/was "conventional wisdom"?


2) Whether it has in fact been proven wrong, as opposed to the latter conclusion being wrong?
7.5.2006 8:09pm
Greg C (mail):
One noteworthy example is the belief that frozen vegetables were less nutritious than fresh because many vitamins begin to denature as time passes. Turns out that frozen vegetables are often more nutritious than fresh per unit of weight due to water loss in the flash freezing process.

Turns out that ketchup and other processed tomato products also have higher micronutrient value per unit volume than fresh tomatoes, and for much the same reason: water loss.

There is also some recent literature indicating that low-fat diets may not prevent cancer as had previously been thought — though the jury is still out on that one.

I don't have the cites in front of me, but I suspect a web search would turn them up. And, if not, a PubMed search ( certainly would.
7.5.2006 8:12pm
One is "Stomach ulcers are a product of stress," which was gospel for many years. Another is that medicine has increased our lifespans. Check out the King James Bible (published in 1611), where in Psalms 90:10 we read that "The years of our days are three score years and ten, or if by reason of strength they are four score years..."; in other words, that long before modern medicine, people died of old age at around 75.
7.5.2006 8:18pm
PK (mail):
Another example: Two Australian doctors eventually won the Nobel Prize by showing that most ulcers are caused by a bacterial infection, not stress, as was commonly assumed.
7.5.2006 8:19pm
Eduardo S:
The definitive example of this in recent days is the "stress causes ulcers" meme. See
7.5.2006 8:20pm
cirby (mail):
"Ulcers are caused only by stress and/or diet."

...which caused a lot of, er, ulcers when two guys (Dr. J. Robin Warren and Barry Marshall) found out that Helicobacter pylori causes ulcers in a helluva lot of people (80% or so of cases), and can be cured by a simple treatment of antibiotics.

Some doctors still don't believe in this cause of ulcers...
7.5.2006 8:22pm
Trent McBride (mail) (www):
Ulcers are caused by stress - ulcers are caused by bacteria.
7.5.2006 8:26pm
Trent McBride (mail) (www):
Wow. cool.
7.5.2006 8:28pm
A. Zarkov (mail):
If you had ulcers or any kind of stomach distress doctors would counsel eating many small meals and dairy. Now you get exactly opposite advice, eat few meals and little dairy. In any case, medications like Zantac are so good it doesn't matter.
7.5.2006 8:28pm
Cyrus (www):
I wish I remembered the term for it, but there's a procedure done during labor where the woman's vagina is cut down to the anus in order to prevent it from tearing. Turns out that it was never based on any studies, it was just something that had always been done, and a study showed that it did no good at all, and in fact sometimes incerased complications. Hope that wasn't too graphic. I'm pretty sure the medical term for the procedure starts with a "p" but that's the best I can do.
7.5.2006 8:30pm
DavidBernstein (mail):
7.5.2006 8:32pm
Jeremy Pierce (mail) (www):
Is there an echo in here?

How about autism caused by parents not being affectionate enough?
7.5.2006 8:32pm
DNL (mail):
Did you hear the one about ulcers?
7.5.2006 8:33pm
For another recent example, see this NYTimes article: "Lactic Acid is Not Muscles' Foe, It's Fuel" from May 16, 2006.
7.5.2006 8:35pm

Urinary tract infections in girls caused by bubble bath. Check out the above interesting article in Slate (scroll down to second item).
7.5.2006 8:37pm
oatbran lowers cholesteral circa 1985 or so.
7.5.2006 8:40pm
bellisaurius (mail):
I'm not an expert in the field, but part of the reason behind these changing coventional wisdoms are based on the issues that the stuides that created them covered. At the time, it was thought that dietary effects on health could be based on peoples and countries whose diets had a lot of the food component in question (fiber, fat, etc...).

As it turns out, the studies, for various reasons (that maybe the component needed to be eaten at younger points in life, that other components of the diet had amplitory effects, etc..) were not neccessarily as applicable as hoped. I guess it was thought that this would replace/enhance life time studies that are typically the gold standard of health and nutrtion (often nurses studies, but one that comes to mind was one conducted on nuns).
7.5.2006 8:46pm
Robert Lyman (mail):
Isn't the "overweight" conclusion based on BMI?

That is, isn't it the case that the conclusion "overweight people live longer" actually more like "guys who work out a lot and are pretty built live longer"?

That is to say, I'm not convinved the CW has been overturned if the CW was that having lots of extra fat was bad for you.
7.5.2006 8:48pm
steve k:
Sorry to be so vague, but all sorts of helpful qualities were ascribed to certain vitamins, especially E, which studies have not borne out.
7.5.2006 8:51pm
bode (mail):
This is an excellent episode of "This American Life" that might satisfy your query.

Act One is the portion I'd recommend:

Act One. An Epidemic Created by Doctors. Alix Spiegel reports on the "Recovered Memory" movement. In the early 1990's people across America turned to experts in psychology for help... and many people were told that the source of their problems could be traced to traumatic events they could not even remember, to memories that had to be recovered through special techniques. In the last ten years, this whole approach to psychology has fallen out of favor. So what happened that so many experts came to believe in a treatment that turned out to make many of their patients worse, not better... and what happened when the patients and therapists figured all this out? (35 minutes)

Sucked to be those poor people!
7.5.2006 8:55pm
Another NYU JD:
"Another is that medicine has increased our lifespans. Check out the King James Bible (published in 1611), where in Psalms 90:10 we read that "The years of our days are three score years and ten, or if by reason of strength they are four score years..."; in other words, that long before modern medicine, people died of old age at around 75."

Wow, PersonFromPorlock, I hope you were kidding with your post. While people do tend to mix up lifespan and life expectancy (and you're right, people so far have always had the same lifespan), medicine has definitely increased life expectancy. The fact that many "lay folk" have incorrectly said that modern medicine has increased lifespan, had they instead said that modern medicine has increased life expectancy, they would have been absolutely correct. This semantics mix up, however, has absolutely nothing to do with "conventional wisdom among health professionals." Health professionals, if they are any good at all, know the difference between life expectancy and life span, and to my knowledge, have never made the claim that medicine increased lifespan.

What's most disturbing, though, is that you offer, as your sole piece of "evidence," verses from the bible. Holy Jesus.
7.5.2006 8:56pm
Veggie_Burger (mail):
1) The belief that margarine is healthier than butter
2) The belief that diet soda is safe
3) The belief that egg yolks are harmful because they contain cholesterol
4)The belief that fat makes you fat
5) The practice of circumcision
6) The belief that water should be fluoridated
7) The belief that high doses of vitamins simply create expensive urine
8) The belief that doctors know something that you don't already know about nutrition
9) That premature heartattacks and heart disease is simply a matter of a bad diet and lack of exercise.
10) That Linus Pauling was wrong about vitamin C.
11) That Western medicine is better than Eastern and Chinese Traditional Medicine.
12) That vaccines, tetnus shots, flu shots are safe and are a good idea
13) That buying organic food is a waste of money
14) That pesticides and herbicides are not making their way into the food chain and into our bodies
15) That milk is a health food for adults
16) That the anorexic look is attractive and healthy
7.5.2006 8:57pm
Ken Arromdee:
Skeptical Inquirer ulcers link

This should be required reading for anyone who wants to use the ulcers example.

It's still against conventional wisdom in the sense that at the idea was once new, but once the idea existed for examination, scientists were willing to examine it. It took a while to become accepted because doing proper experiments takes a while; it didn't take unusually long.
7.5.2006 9:09pm
AK (mail):
Veggie Burger:

Just off the top of my head, I know for a fact you're at least partially wrong on 1, 2, 3, 5, 6, 11, 12, 13. #12 for example: was the polio vaccine a bad thing? Although some of what you're wrong about went from "right" to "wrong" to "right" again so fast that you may not have noticed. Take circumcision. For years it was thought to be healthy, then it fell from favor, and now we know that it helps prevent the spread of HIV. Then again, you probably don't believe that HIV causes AIDS...

Anyway, I cannot believe you have not seen this article from the Times. It contains several great examples, like the "weather aggravating arthritis" and "chocolate causes acne" myths.
7.5.2006 9:13pm
Veggie_Burger (mail):
Two very generous tips from me:
1) Most premature heartattacks and clogging of the arteries can be prevent by taking natural dessicated thyroid supplements (by prescription). Check out
The late Dr. Broda Barnes proved this to my satisfaction.

2) Most people as they age should take Hydrochloric ACID supplements NOT acid suppressants that millions of people currently take by prescription and over-the-counter. Digestive enzymes are a good idea as well.

The body produce gastric juices for good reasons and to suppress them is a phenomenal mistake. I get heartburn just thinking about what doctors advise their patients to do.

I also think constipation is bad for one's health.
7.5.2006 9:25pm
Dilan Esper (mail) (www):
Thet two I thought about were that silicone breast implants were dangerous, and that a high-fat high-protein diet (i.e., Atkins) would not lead to weight loss.
7.5.2006 9:28pm
Grant Gould (mail):
Not too long ago, it was widely believed that ordinary trauma -- cuts and bruises -- could and often did cause cancer. The belief goes way back -- the seventeenth century at least -- but it stuck around until quite recently. In Menarde v. Philadelphia Transportation Co. (1949, IIRC) a victim of a fall from a streetcar successfully sued for injuries including breast cancer.
7.5.2006 9:29pm
Windypundit (www):
I believe the conventional wisdom for first aid for minor burns (1st or 2nd degree if not extensive) was that running cold water over the burn area was bad and that some kind of greasy ointment should be used instead. That changed a few decades ago. Greasy ointments are out, and cold water is now believed to be the best first step.
7.5.2006 9:32pm
Veggie_Burger (mail):
I also don't believe in silver amalgam fillings. They are loaded with DEADLY mercury. Don't put that stuff in your mouth or your kid's mouth if you know what's good for you.
7.5.2006 9:36pm
The Original TS (mail):
After the ulcer thing, the most glaring example is all the purported benefits of a low-fat diet. This had been recieved wisdom for many years. It turned out, however, that it had never been scientifically validated. When studies were done, the evidence wasn't there.

The low-fat meme turned into a crusade and a multi-billion dollar industry. Consequently, when studies were eventually done to test the low carb/Atkins-style diet, many people in the medical community were apoplectic to discover that strict low-carb diets appeared to be just as beneficial as strict low fat diets. Some of these people had vested interests, having built careers as low-fat/dieting gurus. Others were simply appalled that they had been parroting unscientific hokum for so many years.

The story of how the low-fat meme became so generally accepted is a fascinating study of the intersection between politics and public health. It is well-worth looking into.
7.5.2006 9:39pm
Veggie_Burger (mail):
That lobotomies are good way to treat mental illness. This was once a fairly common practice in this country.
7.5.2006 9:40pm
Kevin L. Connors (mail) (www):
It seems like Michael Crichton brought up a bunch of these in his speech, Aliens Cause Global Warming.
7.5.2006 9:43pm
Nathan Jones (mail):
The dust is still settling but: the use of arthroscopy to treat osteoarthritis received a major blow when the New England Journal of Medicine published the results of a randomized, placebo-controlled double blind study by Moesely, et al. in 2002.

The story leading up to the publication of the article is fascinating in an of itself. For decades orthopods used the procedure for osteoarthritis without one shred of scientific evidence that it worked. (Anecdotes don't count there is, as we might imagine, a powerful placebo effect of surgery!) Some surgeons had their doubts and the Moesely paper actually got patients to undergo fake surgeries to test the real versus perceived effects of arthroscopy. Result: the surgery was no better than a placebo.
7.5.2006 9:49pm
That there are no racial differences other than the most superficial, now repudiated by a recognition that the best treatment for some heart conditions among those of african descent is one discarded decades ago because it only helped 12 per cent of the [race blind] populace...

It was always on odd politically driven beleif, but a particualrly odd one to be maintained among a profession with an unusually large representation form a group that was the cause of one of the first genetic registries for disiease to be consulted befoe marriage.
7.5.2006 9:53pm
John Allen (mail):
In the movie Sleeper, Woody Allen says to Diane Keaton:
"Remember when they thought fat and cigarettes were bad for you."
7.5.2006 9:54pm
Greedy Clerk (mail):
What's most disturbing, though, is that you offer, as your sole piece of "evidence," verses from the bible. Holy Jesus.

Even better was that he quoted the King James' Bible as being "published in 1611." Of course that is true, but it is a translation of a document that was most probably written in about 500 BCE (the Psalms). It is amazing how ignorant religious people are about the Bible. Most fundamentalist Christians do not even know that Jesus was a Jew, for example.
7.5.2006 9:55pm
Greedy Clerk (mail):
Scratch that -- I meant Catholics not fundamentalist Christians.
7.5.2006 9:56pm
John Allen (mail):
Amazingly enough, they had X-ray machines in shoe stores so you could see how your feet fit inside the shoes you were trying on. Now I'm afraid that some day I'm going to get toe cancer or something.
7.5.2006 9:57pm
Veggie_Burger (mail):
Avoid antibiotics like the plague! The pun was intended!
7.5.2006 9:58pm
Veggie_Burger (mail):
That a dental x-ray is like spending 5 minutes soaking up the sun at the beach. Nowadays, they cover you in lead aprons and the x-ray technician goes outside the room to take the picture. x-rays are NOT like spending time in the sun; they are dangerous.
7.5.2006 10:01pm
The belief that cerebral palsy in infants was related to trauma in the birth process. Put to rest in the 1980s, yet OBs still get sued for this.

Posters above mentioned the belief that you couldn't lose weight on a low-carb/high-fat "Atkins" diet -- one should add to this the belief that such diets are radically superior to other weight-loss plans. A New England Journal of Medicine Study in 2003 found that a group of low-carb dieters lost more weight in six months than participants on a "standard" diet -- but the difference was only 4%. After a year, there was no statistically significant difference.
7.5.2006 10:01pm
John Jenkins (mail):
Did DB intend to attract nutjobs with this post?


16-Is misleading. Different people like different things, but I don't know that anyone has ever thought that looking emaciated was a good thing. That some people take "thin &healthy" a little far doesn't make thin &healthy wrong as such.

15-Lots of people have problems with milk. Lots don't. It's not bad as such, no matter what weird conspiracy websites have to say.

14-This is an idiotic statement. Of course they are. Dose, however, is important. Given the increase in life expectancy discussed in this thread and the number of people that the Earth is able to support food-wise, I'd guess it's not the problem you think it is.

13-It is unless you prefer the taste. I only buy tomatoes from local farmers because the varieties in stores are tasteless. Organically raised produce is treated with poisons just as bad as chemical herbicides and pesticides (in large doses) that just happen to be natural.

12-Yeah, I think that Polio is a much better option than the vaccine was. Ditto smallpox.

11-If by "better" you mean "does something," then I'd say CW is right on target.

10-On which claim? He wasn't ever RIGHT about anything, and if you have data to the contrary (data meaning peer-reviewed double blind studies of any kind, not lunatic websites) I'd love to see it.

9-Genetics are a bitch, but both of those are contributing factors. Dietary supplements of dessicated animal organs are probably not an effective treatment (data?).

8-Doctors aren't generally educated in nutrition (though that is changing). That's why we have nutritionists. This is like saying your Lawyer can't run your factory floor.

7-That's not true. They can also kill you given that some vitamins are not water soluble. Those are seriously insane doses though. In normal doses that you could manage to take, they do cause expensive urine and have no proven positive health effects (data?)

6-Data to the contrary?


4-Second law of thermodynamics-look into it.

3-Not really CW anymore so on this one you're rightj!

2-Not shown to be harmful and, no, aspartame can't convert into formaldyhide in the body. Sorry to disappoint.

1-Neither of them is a particularly good idea, simply because you're dealing with something that's 9 cal/gram, though butter adds good flavor whereas margarine doesn't. Don't be surprised if the crusade against trans-fats turns out to be as baseless as the crusade against eggs was.

My list:

Height/weight tables (or BMI) tell you anything at all (they don't, variations among different people are too great).

You need to be on a low sodium diet if you have high blood pressure (only about 10% of the population is sodium sensitive: for most people drinking enough water solves the problem).

Some favorites from lifting/fitness:

The 8 glasses of water is a great one.

Two alternatives:

1. You must have HUNDREDS of grams of protein per day; or
2. You may NOT have more than 50 grams of protein per day (lest ye die!).

You have upper abs (you don't. You have a rectus abdominis which is one sheet of muscle and two sets of obliques).

I could go on for DAYS on this. I used to work in a health food store and the things those people believe make me laugh (and made me a living before law school: thanks crazy people!).

Here's a free bit of advice from me: When you walk into the health food store asking if they have anything to help you to lose weight, finish your ice cream cone first or they'll be making fun of you for years.
7.5.2006 10:15pm
Brett Bellmore:

that silicone breast implants were dangerous

I'm not sure that was ever the conventional wisdom outside the tort law profession. There was never any real evidence to support it, after all, and it was pretty conclusively proven false long before Dow took it in the neck from the courts.
7.5.2006 10:20pm
The Original TS (mail):
Posters above mentioned the belief that you couldn't lose weight on a low-carb/high-fat "Atkins" diet -- one should add to this the belief that such diets are radically superior to other weight-loss plans.

The call of the question had to do with conventional wisdom among health professionals that turned out to be wrong. It has never been conventional wisdom among health care professionals that low-carb style diets are superior!

BTW, another somewhat more amusing one was the (still) common belief that that you must wait 1/2/3 hours after eating before going swimming lest ye suffer cramps and die. IIRC, this had its genesis in a first-aid book published by the Red Cross in the mid/late fifties. Subsequent editions removed it but it was, for some reason, already firmly entrenched in the public consciousness. Kind of ironic since I doubt anyone ever remembered any of the correct information from that particular book. I don't know if this qualifies as I don't know how widespread this misinformation was amongst the medical community.
7.5.2006 10:35pm
While I wouldn't call it "wisdom" I do have some thoughts on how "unproven theories" become "conventional wisdom" despite the lack of "hard data." For one thing, it is only a very small slice of our collective "knowledge" about the world that has actually been "proven" to be true through "hard data." Even those theories that have been so proved, like the theory of gravity, leave behind gigantic holes and unanswered questions. How is society to function when most of what we know about the world is, in a scientific-hard-data sense, not "known" at all? Well, we respond as we always have: behaving and advising others to behave in a manner that comports with our general experiencies of what works and what doesn't, combined with a healthy dose of reasonable inferences. The result is that a whole lot of information that gets bandied about in casual conversation, professional advice, or blog comments is only marginally aligned with observable phenomena in the physical world. As our ability to percieve observable phenomena improves our scientists are able to establish more and more facts as more likely true than not, and they hope that those observations stand the test of time, but they usually don't. So I guess I would suggest, in response to your querry about why "unproven theories" become "conventional wisdom," that the vast majority of what we think we know about the world is only "unproven theories" turned "conventional wisdom" and that most if not all of it will eventually crumble to a new regime of unproven theories turned conventional wisdom. And so on and so forth until we're all oblierated in nuclear fire...

That and, btw, OB malpractice can and does cause cerebral palsy -- though it is relatively rare - cerebral palsy can be caused by oxygen deprevation during the birthing process. For most cases of cerebral palsy the cause, not surprisingly, remains unknown.
7.5.2006 10:41pm

What's most disturbing, though, is that you offer, as your sole piece of "evidence," verses from the bible. Holy Jesus.

Why not just wave a cross (presumably upside-down) at me and shriek "unclean!". If in 1611 the authors of the KJV were comfortable with the statement that people lived about 75 years, that simply implies that it was the common experience of the time.

Assume that the authors made the verse up on the spot, or that they were faithfully translating something written in 500 BCE, and it doesn't affect my point at all: between 1611 and now, there's been little change in how long we live -- although modern medicine has certainly helped more people to reach that limit.
7.5.2006 10:48pm
Fresh Air (mail):

It's worse than what you say. There are many theories that can't be proven or have been disproven yet are still held out as truth. So-called secondhand smoke causing death and disease in non-smokers is one of these. There are others. As to why, there is certainly a great deal of politicization among the health establishment in this country, which is overwhelmingly liberal and nannying. The better question is why aren't these things refuted more effectively?

The answer, I believe, is that the MSM reporters who handle many stories of scientific "breakthroughs" really have no idea what they are writing about. They don't know the medical literature, they couldn't research the research if they tried, and they aren't even able to ask intelligent questions. Try this experiment: Look up any article on Lexis/Nexis for a major scientific study being published. How many critics of the research do you see quoted? Most of the time you won't find any.

The trouble with many of these "landmark" (often longitudinal) studies is that they are based upon epidemiology, which has serious threshold limits before it is a useful, prescriptive tool.

Any time, for example, you see a study that shows a less than double, or 200%, increase in risk of disease, it is probably best to ignore it. This is the mathematical level below which epidemiologically derived risk factors are just as reflective of chance as of some behavior or other cause.

The American Cancer Society doesn't want you to know, for example, that over 95% of the disease found in their epidemiological studies of "passive" smokers are not attributable to smoking at all, but rather something they cannot even identify. This sort of subterfuge is rampant among the medical establishment, (which in this case has an open field due to the prior neutering of the tobacco companies from the Big Tobacco settlement).

Not to dwell on passive smoking, because there are other examples. I recall a few years back women's health groups went nuts when a study was published linking abortions to cervical cancer. They claimed the RR (relative risk) wasn't high enough, but it was much, much higher than the RR for secondhand smoke.

Yes, there is a double-standard. But there are also a lot of intellectually dishonest "advocates" out there who are foisting crap on the public and the MSM is simply recycling their talking points instead of taking a properly skeptical attitude.
7.5.2006 11:26pm
Frank Drackmann (mail):
Don't let cats around a baby because the cat will steal the babys breath and it'll die.
7.5.2006 11:33pm
D. Ashbaugh (mail):
As a retired Doctor, I have seen many theories come and go and most often the reason is just better science. In my early years, this debate was largely within the profression, but now the good, bad and purely awful science all get thrown into the public arena post haste and the public is left to sort it out, which can take a while.

D. Ashbaugh, MD
7.5.2006 11:56pm
Amber (www):
I thought the whole being cold leads to catching cold thing was true.
7.6.2006 12:22am
A very recent one. Lactic acid is bad for you. turns out not so.
7.6.2006 12:25am
I think the piece de resistance has not yet been mentioned yet, and that is: that washing hands with soap and water between patients prevents infections from being transferred from patient to the doctor.

Yes yes I know some guy in Europe, Semmelwiess or something, came up with that in his gynecological practice in Europe in the 1800's with respect the horrific infections of post natal women and puerperal fever. The guy eventually went crazy, but doctors finally figured out that, yes, washing hands does prevent infection transfer.

Now why would I mention this 1800's thing as recent? One need only frequent medical sites and reports such as Reuters Healthline, Medscape and others, to run across, fairly routinely, that hospital infections are reduced if, yes, doctor's and other health professionals wash their hands between patients.

Thus, not only was the absolutely and totally incorrect conventional wisdom of the 1800's proved wrong, but also it has revived itself.
7.6.2006 12:54am
lee (mail):
At fifty my father developed a peptic ulcer. There wasn't much stress in his life other than the "bland diet" the doctors put him on for 5 years. Surprise, surprise, it didn't work! I guess the operation in which they removed 2/3 of his stomach was pretty stressful too, but it worked. And to think, 2 antibiotics for 2 weeks!
7.6.2006 1:41am
Not sure if these qualify:
1. Global Ice Age cometh - early 1980s. (Now its Global Warming, or better yet - the always right Climate Change).
2. The Population Bomb - published in late 1960s. We're all going to starve to death for lack of food! Ooops.
3. Homosexuality as a Psychological Disorder. Not making a judgment one way or the other here, just noting that until about 30 years ago the APA considered it a disorder, and now it is considered akin to a genetic trait.

### Other Notes
a. Greedy Clerk, not sure how your Catholic reference works in. What Roman Catholics would use the King James Version of the Bible? The other remarks about the passage dating to 1611 made me LOL.

b. Circumcision. I think what Veg refers to is the common consensus that circumcision was healthier than no circumsicion. It's really as question of cleanliness. As long as you shower regularly with soap (uncommon during Biblical times, when the practice arose), circumsicion provides no health benefit of avoiding infection. As for reducing the risk of contracting HIV via sexual intercourse, if that is true (brief search indicated possible, but not conclusive), I'm not sure that this is a compelling case for circumsicion.
Circumsicion seems to be behind at least: 1) limited sex partners, 2) condom use and 3) no anal sex, as a way to avoid HIV.
Having said all that, I've got nothing against those who "nip the tip." It's a fine religious tradition, but as a goy, it wouldn't do much good.
7.6.2006 1:54am
AK (mail):
Greedy Clerk:

Catholics don't know that Jesus was Jewish? Please give me a second to regain my composure. Perhaps by the time that I stop laughing, you will have come up with some evidence for your assertion.

If you're going to distinguish Catholicism from other Christian churches and communions, the most obvious difference is in the Sacrifice of the Mass, in which Catholics participate in the inseparable sacrifices of the Last Supper and the Crucifixion. The Last Supper, of course, was a Seder, and nothing in Catholicism has ever tried to diminish that or hide that. Rather, the Church has always emphasized the links between the Last Supper and Passover. If you look elsewhere in Catholicism, more than any other branch of Christianity, you will see evidence of the links between the Old Covenant and the New Covenant. Jesus is the new Adam; Mary is the new Eve. Mary is also understood to be the new Ark of the Covenant.

I don't doubt that there are misinformed Catholics out there. If you ever want to spot one, look for the person who prefaces a statement with "I was raised Catholic..." and you'll know that you talking to someone who knows about as much about Catholicism as you do.
7.6.2006 2:42am
jfd (mail):
Wot about 'margerine' prevents heart disease 'cause it lowers cholesterol (not often, we know now) and is way, much better than butter for health?

Now it's widely believed, based on long-resisted research, that synthetic 'trans-fats' can worsen/cause heart disease, obesity, diabetes and, perhaps, even cancers.


There's a libertarian [?] angle here in that it can be argued that the AMA was suborned by a powerful political cabal of corn growers (have to sell that corn oil somewhere), the Dept. of Agriculture, and the FDA (Foods ain't Drugs, Alright?).

So, government-sponsored market distortion distorted scientific research, suborned the medical profession, and wreaked serious damage upon Americans' health.

Worse, just wait until research into health effects of extremely processed vegetable oils seeps into the health administrative mainstream...
7.6.2006 3:45am
M. Simon (mail) (www):
The belief that drugs cause addiction. (the foundation of the War On Drugs).

The NIDA now says that chronic drug use has two factors.

1. Genetics
2. Environmental factors (what I prefer to call trauma)

Needless to say most folks have not caught on to this yet. Not even anti-prhibitionists.
7.6.2006 6:42am
Parsi (mail):
I recommend Part 3 ("The Fall") of (Dr.) James Le Fanu (1999)
The Rise &Fall of Modern Medicine, Abacus/Little Brown.

Although intended for a lay audience, the book has extensive
footnotes, references, and a thorough index. It contains
much material relevant to your paper.
7.6.2006 7:10am
Wow, there are so many posts that I'll just add my few without bothering to read all of the ones above to avoide dupes.

1) Of all things, blood letting.
2) Also, a recent French study in Africa showed that circumcision actually reduced AIDS transmission rate 30% or so. Now it might be medical malpractice not to recommend it!

7.6.2006 8:36am
Oh yeah, another one:
It seems that new research says that vitamin D is so important to fighting cancer that it outweighs the ill effects of getting sunburned. Admittedly, this is a recent study and subject to much refution by the entrenched anti-sun crowd.

7.6.2006 8:45am
In the 1980s, observational studies suggested that high dietary intake of beta-carotene (an antioxidant and precursor to vitamin A) might reduce cancer incidence. Based on this finding, two large-scale, long-term, double-blinded, placebo-controlled clinical trials were performed to determine whether beta-carotene supplementation could prevent lung cancer in smokers (one study also enrolled former smokers and persons exposed to asbestos). Beta-carotene supplementation was also advocated by health magazines, etc., to the general public.

Both the Finnish ATBC study, which included more than 29,000 participants, and the U.S. CARET study, which included more than 18,000 participants, found statistically significant increases in lung cancer incidence in the participants who had received beta-carotene. Lung cancer incidence was 16% higher in the ATBC study, and 28% higher in the CARET study.

Interestingly, beta-carotene supplements have not been found to increase cancer incidence in non-smokers.
7.6.2006 9:12am
Two examples:
1. Ice water lavage (using a nasal gastric tube to add ice to the stomach) was thought to be an effective treatment of gastric bleeding. A perfect way to waste hours of a medical students life, but unfortunately not effective (and maybe dangerous).
2. That antiarrythmic drugs (see Fleicanide) are helpful for preventing fatal arrythmias after a heart attack, even if no rhythm disturbances has been noticed. (actually increases risk of fatal arrhytmias).
7.6.2006 9:25am
By the way, dental x-rays aren't particularly dangerous. The radiation dose is small compared to what we all get all the time from natural sources. The technician leaves the room because he or she is exposed to many of these sessions per day, not just one or two a year, and the dose is cumulative. The lead apron is just an extra precaution, not an essential shield against something really awful.


Health Physics Society FAQ for Dental Patients

for some numbers on radiation doses and for a general discussion.
7.6.2006 9:31am
Houston Lawyer:
Babies should sleep on their stomachs. Lileks has a whole book on bad mothering advice given during his lifetime. I'm sure it's a rich source.

In the late 50's, breast feeding was discouraged. Doctors often gave women shots to stop lactation without the woman's consent.
7.6.2006 11:27am
sierra (mail):
Windypundit: I don't know why or where I heard about it, but onion juice (or pulp) is superior to cold water for first degree burns. (Since second degree burns involve blistering, you probably don't want to risk getting it infected.)
7.6.2006 11:48am
sierra (mail):
Veggie_Burger: a recent study confirmed mercury fillings are safe.
7.6.2006 11:52am
Richard Bellamy (mail):
"Multiple Personality Disorder" was very popular for a while because it worked in very well to the plot of B-Level murder mysteries.

It has since been removed entirely from the DSM -- replaced by something called "Dissociative Identity Disorder" -- which also may or may not exist.

The idea, though, of multiple unique individuals with no knowledge of each other residing in the same body is now widely believed to be total bunk.
7.6.2006 11:59am
Seamus (mail):
Another is that medicine has increased our lifespans. Check out the King James Bible (published in 1611), where in Psalms 90:10 we read that "The years of our days are three score years and ten, or if by reason of strength they are four score years..."; in other words, that long before modern medicine, people died of old age at around 75.

Uh, "three score and ten" is 70 years, not 75.

And in any event, you only got to be 70 years old if you survived the horrible infant mortality of those days. You don't suppose medicine has had anything to do with bringing that mortality down in the last couple of centuries, do you?

(But it's true that claims that "life expectancy back then was 30 [or 40, or 45] years" is based on averaging the ages of everybody's death, which is skewed by infant deaths; it doesn't mean that people typically dropped dead at around 30, or 40, or 45.)
7.6.2006 12:28pm
Aaron B. Dossett:
kidney stones is turning out to be
wrong. Since most kidney stones are calcium
stones, the conventional wisdom has been to
limit calcium intake to prevent recurrence.
But evidence shows that this approach actually
leads to more stones, and that reducing
sodium and protein is more effective."
7.6.2006 12:56pm
I can't believe the hostile reactions to PersonfromPorlock's entry that quoted the Bible. Maybe his example isn't on point because, among health professionals, life span (as opposed to life expantancy) isn't thought to have increased over time. But it seems like a book published in the 17th century that was a translation of something published centuries earlier would be fairly good of how long people lived during that time. If a man from Jordan's profession was listed as "goat-herder" in the Bible, isn't that fairly good evidence that people in Jordan herded goats? Now, it'd be nice to corroborate that with the fossil record or other evidence, but I'd wager that there were, in fact, goat herders.

Seamus, uh, 75 is halfway between "three score and ten" and "four score," which were the two ages listed. I'm guessing that PersonfromPorlock just picked the midpoint, you (phrase deleted in deference to VCs "civil comments only" policy).
7.6.2006 1:39pm
"...would be fairly good of how..." should be "...would be fairly good evidence of how..."
7.6.2006 1:41pm
Bill Gardner (mail):
Most of the previous suggestions concern epidemiology, rather than medicine or surgery. There many examples, however, of medical interventions that were accepted as standard care based on 'clinical experience', yet were discarded after they were tested using randomized clinical trials. Your best lead for details might be a heart surgeon.
7.6.2006 1:54pm
MDJD2B (mail):
I wish I remembered the term for it, but there's a procedure done during labor where the woman's vagina is cut down to the anus in order to prevent it from tearing. Turns out that it was never based on any studies, it was just something that had always been done, and a study showed that it did no good at all, and in fact sometimes incerased complications. Hope that wasn't too graphic. I'm pretty sure the medical term for the procedure starts with a "p" but that's the best I can do.

The procedure is called an episiotomy. It was routine when I was an OB/GYN resident in the 1970's, but is now restricted to special circumstances (or should be).
7.6.2006 2:52pm
MDJD2B (mail):
Until less than 200 years ago, and for almost 2000 years previous, doctors thought disease was caused by an imbalance of the four humors: blood, phlegm, black bile, and yellow bile. this led to such practices as bleeding and purging.

In the years immediately post WWII, gynecologists thought you could treat infertility in women with retroverted women by surgically sewing them into the forward position. This is no longer accepted.

Also in the years post WWII, topnsillectomies were commonly performed for recurrent upper respiratory infections. I don't know if this was consistent with academic conventional wisdom, but I had it done.

Did anyone mention lobotomy for the treatment of mental illness. This may not be such a great example. It DOES affect behavior, but does not restore it to normal. In those days, it may have been better than nothing in some cases.

Psychiatrists believed that a cold "refrigierator" mother was the cause of autism, and that mothers who presented "double bind" choices to their children were responsible for schizophrenia. These beliefs caused a lot of guilt in a lot of parents, before they were demonstrated to be untrue. Indeed, "talk therapy" without drugs used to be considered more efficacious in treating psychiatric diseases with a strong biologic basis (like schizophrenia and mood disorder) than it is at present.

It used to be thought that activity caused early miscarriage, and that bed rest was effective treatment. Now it is appreciated that first trimester miscarriage usually is due to gross genetic defects.
7.6.2006 3:12pm
Ronald Thisted (mail):
Regarding example 4 (tomatos and prostate cancer), the jury is out, but the evidence leans in favor of tomato consumption reducing risk of prostate cancer. The FDA judged that "The limited scientific evidence describing the effects of tomatoes and tomato products on prostate cancer, suggests that consumption of one-half to one cup of tomatoes and/or tomato sauce per week may reduce the risk of prostate cancer" in 2005. A clinical trial sponsored by the National Cancer Institute that may settle the issue is currently under way.

Regarding example 2 (overweight reducing life expectancy), again, the jury is out, in this case, way out. The debate centers on what to make of consistently replicable associations. The evidence is strongest for increased weight being associated with increased risk of various cancers, and of cardiovascular disease, both of which would, ceteris paribus, lead to reduced life expectancy. But detection and treatment in both areas are improving, diet is changing, etc. That makes it tough both to detect associated differences in life expectancy and to attribute the causes of any differences that are found.
7.6.2006 3:16pm
Anderson (mail) (www):
Great example: that stomach ulcers are caused by stress, when they've been proved to be caused by bacterial infection. The Australians who advanced the bacterial theory were practically ostracized for years but have now (2005) won the Nobel.

(I've not read the thread, but searched for "ulcer" on this page &got no hits; sorry if already ID'd.)
7.6.2006 3:24pm
MDJD2B (mail):
Three more great examples:

Breast cancer must be treated by en bloc excision of the entire breast and lymph nodes (removal of these structures in one piece, with all the intervening tissue. This is no longer believed necessary, except in large tumors.

The definitive operation for breast cancer must be done at the same time as the biopsy, lest the biopsy spread the disease. Simple old wives' (or old doctors') tale.

Serum estriol levels predict the development of fetal distress. This test was almost universally done on pregnant woman during the 1970's but has been discredited.

BTW, Prof. Bernstein, be sure to distinguish between change of conventional wisdom due to demonstration that it is wrong, and change in CW because something better came along.

For example, the use of forceps in prolonged second stage of labor has been somewhat discredited (I don't want to go into technical detail). This is not because OB's came to realize that spontaneous vaginal delivery is actually safer for the baby, but because cesarean section became safer for the mother, and emerged as a third, best, alternative to forceps and unassisted vaginal delivery.
7.6.2006 3:42pm
That the "Pneumonia shot prevents Pneumonia" it does not. It prevents sepsis from the most common cause of bacterial pneumonia (Pneumococcal pneumonia). That "treating strep throat with Pencillin make the sore throat go away quicker" it does not. It is treated to prevent latent complications (Rheumatic fever and a type of kidney damage). All caused by antigen-antibody caused disease. If you take the antibotic within 9 days of the sore throat these latent diseases are prevented.
7.6.2006 6:42pm
M. Simon (mail) (www):
Richard Bellamy,

May I suggest "Societies of the Mind" by Minsky.

Every one has multiple personalities. When they don't work well together or don't communicate it is called MPD.

If you have never lived with such a person, don't. For the most part they are abused children. So with a little effort you can avoid them.
7.6.2006 6:45pm
Zed Pobre (mail) (www):

Actually, stress is still considered a major factor:

In any case, as posted above, the history of ulcer treatment is not how it is commonly presented.
7.6.2006 7:10pm
leucanthemum b (www):
How about the standard treatment for allergies? It used to be recommended that a person avoid known allergens at all cost, but now they're using controlled exposure as a method of immunizing patients.

And, hey, while we're on the topic of allergies, remember when kids with continuous sniffles and wheezes were simply referred to as "sickly"? And they wouldn't let those kids go out to play with the others, because they were too frail. Now, they're discovering that, the more the asthmatic kids exercise, the less severe their asthma attacks may be.
7.6.2006 8:10pm

scientific evidence describing the effects of tomatoes and tomato products on prostate cancer, suggests that consumption of one-half to one cup of tomatoes and/or tomato sauce

To be complete, it is tomatoes and tomatoe (sic) products cooked with oil, such as olive oil, for the best bioavailability of the lycopenes.
7.7.2006 12:00am
Houston Engineer (mail):
The procedure is called an episiotomy. It was routine when I was an OB/GYN resident in the 1970's, but is now restricted to special circumstances (or should be).

Unfortunately, I've heard of OB/GYNs (which is a surgical specialty, by the way) that don't believe the research, and still use episiotomy regularly, even against the clear wishes of the mother.

Obstetric Myths vs. Research Realities has a whole chapter on this one. It's Chapter 14, so there are at least 13 others to add to your research, David.

Of course, episiotomy is less common now, because doctors are more likely to just do a c-section. The common wisdom seems to be that you can't get sued if you do a c-section, because you 'did everything you could for the baby.'
7.7.2006 2:05am
Harry Eagar (mail):
That asthma was pyschosomatic.

I cannot decide whether I am amazed that no one has cited Bendectin, or that -- since I am among lawyers -- I would be amazed that anyone would cite Bendectin.

The question is, whose conventional wisdom? The medicoes' completely wrong notions about asthma were clearly CW.

That Bendectin causes birth defects is CW among scientifically illiterate feminists and plaintiffs' lawyers, but is, I believe, recognized as witchcraft by real doctors.
7.7.2006 2:31am
Harry Eagar (mail):
Here are 2 more. The first I am also surprised was not mentioned already.

1. That global warming (itself a myth in the historian's strict usage and probably also a myth in the everyday meaning of an imaginary event) will lead (or has already led) to the spread of tropical diseases into temperate zones.

The disease usually mentioned first is malaria, which is not a tropical disease. It used to be common in northwest Europe and was the leading cause of death among whites in Illinois in the 1840s.

There really are tropical diseases, but those cited in this piece of misplaced CW are usually diseases of poverty, which is prevalent in the tropics. Hansen disease (leprosy) is virtually unknown except in the tropics today, but it is named after a Norwegian doctor because it used to be endemic in Norway, and not so very long ago either.

(Similarly but oppositely, diseases that are strongly affected by weather and have been great killers in temperate zones, like glanders and typhus, are not great killers today in the tropics, but not because it is too warm for them there.)

2. That indigenes of the New World were especially susceptible to European (or, as the historian W.H. McNeill correctly labels them, mostly African) diseases because they lacked natural immunity.

So they did, but so did everybody else. The bitter dispute between Cotton Mather and Ben Franklin about inoculation should put paid to the notion that Europeans thought themselves naturally immune to smallpox.

Similarly with other killer diseases like TB or measles. The reason Europeans in the New World or Oceania did not succumb in the proportions that the natives did (when the ratio went that way, which it did not always) was not natural but acquired immunity. The infants who died of TB, measles, smallpox, plague etc. in Europe were not available to die again as colonists in Massachusetts or Hawaii.

This example does not quite fit Professor Bernstein's inquiry, because although CW on this topic is undoubtedly wrong, it has not yet been overthrown.
7.7.2006 4:52am
Colin (mail):
I'm not sure why you think that the conventional wisdom holds that aboriginal populations were more susceptible to imported diseases because they lacked natural immunities. I think the explanation has always been what you describe - acquired immunities in colonists who had already been exposed to the diseases gave their communities an advantage in limiting their spread and severity.

Bernstein asked "how unproven theories become conventional wisdom in the absence of hard data." One vector is the assumption of authority; people who claim factual knowledge and take the position of an expert are persuasive when they make factually unsupported but intuitively reasonable claims. At the same time, an audience that wants to be informed but doesn't have the wherewithal to do the legwork itself can assume the authority of an informed opinion by accepting a convenient or sympathetic position as true and well-supported, even if there's no objective reason to think that it is. Arguments that sound right substitute for evidence for most of us, most of the time, at least on issues that we don't have the time or inclination to study first-hand.

Eager's claim, without support, that global warming is "a myth in the historian's strict usage and probably also a myth in the everyday meaning of an imaginary event" is an off-the-cuff example. The situation is not nearly as simple or as open-and-shut as the blanket statement makes it appear, but the confident and authoritative statement might easily persuade a reader who is not familiar with the scientific literature or unwilling to do the outside reading. That's especially true if the idea being sold is an attractive proposition--if, for example, it is politically convenient to accept the argument.

"Stolen election" stories are another example. (Not an example of a scientific or medical myth, but at least it makes my argument bipartisan.) Even in the absence of actual data, a tempting or convenient argument can seem very persuasive and authoritative, so long as its sold with confidence. The confidence of its presentation increases with its acceptance, building conventional wisdom that supports attractive and intuitive propositions.

I assure you, with all the weight of my tremendous experience and authority in this field, that my statement is correct and insightful.
7.7.2006 1:29pm
Harry Eagar (mail):
Except in my own writing, I have never seen anyone make the, obviously correct, deduction about acquired immunity. That the New World natives lacked natural immunity is a commonplace, repeated, for example, by the otherwise reliably skeptical Pultizer Prize-winning historian Walter McDougall in his new history of the U.S., 'Freedom Just Around the Corner.'

Just because I didn't present my evidence about GW in a short blog post doesn't mean I don't have it.

The strict definition of myth is that which almost every member of a group (usually a national group) shares. When historians use the word that way, there is no presumption that the belief is incorrect.

To give two examples:

Until around 1960 it was an American myth that Americans are/were the free-est people on earth. That myth seems to have lost some of its status in the past half century, but it probably was true generations ago and is true now.

The French have a myth that the French are the most logical people on earth, although this was probably never true and certainly is not true today, although the myth is as strong there as ever.
7.7.2006 3:08pm
Ken B:
Umm ... it probably is generally good for PM women to be on estrogen. There are a lot of proven benefits. It is just not the case that all should be or that no elevated risk factors exist. But if my sense of what you want to argue is right this is a poor example, because the conventional wisdom is mostly right: it has been modified not overturned.

Ulcers is the example you want.
7.7.2006 3:38pm
Hey, how about maggots as a treatment for gangrene? In, then out, now somewhat back in.
7.7.2006 5:04pm
Harry Eagar (mail):
Probably the most theatrical contest between CW and an eventually triumphant critic was Martin Couney's infant incubator, which operated for 39 years (1904-43) at Luna Park at Coney Island.

Couney imported the idea of incubating premies from Europe but was ridiculed by the medical establishment and denied hospital access. So he set up his neonatal unit as a carnival attraction, first at the Trans-Mississippi Exhibition, later permanently at Coney Island. There was even a rival incubator at Dreamland for a while.

Even after he had saved hundreds of babies, he had a monopoly for years because M.D.s wouldn't admit they were wrong. For a long time, the only place to get treatment for prematures was at the amusement park.
7.8.2006 12:59am
Michael F. Cannon (mail):
John P. A. Ioannidis, "Contradicted and Initially
Stronger Effects in Highly Cited Clinical Research," Journal of the American Medical Association 294 (July 13, 2005): 218--28.

John P. A. Ioannidis, "Why Most Published Research Findings Are False," PLoS Medicine 2, no. 8 (August 2005): e124.
7.13.2006 7:02pm
Michael F. Cannon (mail):
Joan: Will she be alright?

Theodoric of York: Well, I'll do everything humanly possible. Unfortunately, we barbers aren't gods. You know, medicine is not an exact science, but we are learning all the time. Why, just fifty years ago, they thought a disease like your daughter's was caused by demonic possession or witchcraft. But nowadays we know that Isabelle is suffering from an imbalance of bodily humors, perhaps caused by a toad or a small dwarf living in her stomach.
7.13.2006 7:07pm