Mythology, Medicine & Backwards Nephrology
Single individuals can influence the direction of entire scientific fields for purely social reasons, leading to an illusion of scientific consensus and decades of backwards medical advice.
Not medical advice.
Myths have a powerful, animating effect on human behavior. From religious fundamentalists to Lord of the Rings fans and scholars of ancient mythology, the human mind is drawn to symbolical stories like a moth to a flame. But myths do not operate solely in the realm of fiction and religion. They are also a powerful animating force in science and medicine. In fact, myths can be especially potent in this realm because we often don’t recognize them as such. Even hardcore scientists and practicing physicians fall prey to the power of compelling fictions. An entire career can be spent in devotion to ideas never firmly tethered to empirical reality.
According to the general mythos of Western science we inherited from the Enlightenment, science is progressive. Slowly but surely, we march forward in the general direction of objective truth, moving sideways here and there but never turning backwards or driving blindly off-road and into a ditch of superstition. An iterative trial-and-error process of careful experimentation and disinterested observation, mediated by the sacred practice of peer review, is constantly eroding away our ignorance of the natural world. The work is dutifully carried out by credentialed experts (our modern-day priest caste)—special people, rigorously trained to engage in stone cold scientific reasoning and to eschew the more subjective, emotional, and nakedly self-interested thinking styles of regular folks.
In medicine, physicians don’t treat patients based on unproven hypotheses passed on by fiat or by chance. Diagnoses are made and remedies prescribed according to textbook knowledge. Our knowledge may be imperfect and subject to change, but only the most rigorously vetted facts make it all the way into medical textbooks and codified into official, nationwide guidelines.
For better or worse, science and medicine often do not conform to this mythological ideal.
The process by which scientific knowledge is transformed in medical practice does not take place in some sacred realm, divorced from the social forces that motivate the decisions of primates jockeying for position within status hierarchies. An education is scientific thinking does inoculate the human mind, to some extent, from the various cognitive biases and flights of fancy that we’re prone to. But that inoculation is far from perfect.
The simple historical truth is that entire fields of medical practice can and often have been mistaken, sometimes for many decades on end. And not simply because it took time to slowly discover more truths and diligently revise and update our prior beliefs, step by step. That stuff does happen, don’t get me wrong. But there are other, much less flattering patterns to be found in the history of science and medicine. The ideas of a single person can enter the formal scientific discourse and become crystallized as “textbook facts” despite the existence of plausible, competing hypotheses. In some cases, these hypotheses lack empirical support almost entirely. They win the hearts and minds of a plurality of experts not because they’ve run through some ironclad gauntlet of peer review and experimental falsification, but because of social influence. An illusion of consensus among experts can thus be created, affecting the health of millions.
“A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.”
—Max Planck
Protein Intake & Kidney Health: How an unproven idea became a textbook medical fact
I recently spoke to a top kidney biologist on M&M #186, Dr. Thomas Weimbs. He not only shared with me lots of practical knowledge about kidney health, but a fascinating piece of medical history illustrating how an unproven hypothesis can masquerade as medical fact for decades on end.
The myth: High protein diets are damaging for kidneys.
I’d heard this many times in my life. After asking Dr. Weimbs, about it. He told me the story of nephrologist Dr. Barry Brenner. I recommend listening to the audio of Dr. Weimbs directly (at about the 45 minute mark here), in his delightful German accent. Here’s an abbreviated and lightly edited text version, given in response to the question: Can high protein diets be problematic for the kidneys?
Dr. Weimbs: That’s a very old myth. It actually originates from a paper from the 1980s, by a very prominent nephrologist, Barry Brenner. It’s called the, “Brenner hypothesis.” Barry Brenner went on to write the textbook on nephrology that every single nephrologist in the country has studied. It’s a very interesting story.
It was almost a theoretical paper. There were some indications from [non-human] species that, yes, if you eat some protein your kidney filtration goes up. That all makes sense. Brenner essentially postulated that if you eat more protein, your kidney filtration goes into overdrive and you hyper-filtrate, and that ultimately would be detrimental for kidneys and you end up with chronic kidney disease.
That was the dogma for many decades and has made it into all of the clinical guidelines. Oftentimes people with kidney disease are advised to cut down their protein intake, sometimes dramatically. The threshold for malnutrition for protein intake is about 0.8 grams per kilogram body weight—that’s what the government says, you gotta be above that. But people with kidney disease often are advised to be below that, sometimes even way below that.
NJ: All because this guy had a hypothesis, and he wrote the textbook?
Dr. Weimbs: Yes. And there were some studies done, but nothing actually ever really proved anything. But it turns out that more recent studies have pretty much across the board shown that protein consumption is not really associated with chronic kidney disease. But it takes like 20 years for studies to make it into clinical practice. So we’re still behind here.
Unfortunately, many people with kidney disease are still advised to cut down their protein intake, but then they end up being malnourished. They end up with sarcopenia, muscle wasting. There was a recent paper that looked at patients with chronic kidney disease, that were either on a low protein or normal protein diet. They lived longer on a higher protein diet.
As we went on to discuss, this is not some strange historical anomaly. This type of thing is found in many episodes of medical science history. One person holding outsized influence in a field can propel their ideas forward by means other than raw scientific merit. An unproven hypothesis can become “consensus knowledge” among a critical mass of scientists or physicians, and it takes decades and decades to rein in.
NJ: It’s just amazing, one more example out of many in the history of medicine. We normally like to think that everything that's in clinical practice has gone through this rigorous chain of vetting, going from basic research to clinical research to proven, bona fide facts in textbooks. And then we put it into practice. But in many cases, there are things that are put into practice that are not only wrong, but based on ideas that often can be traced back to a single socially influential person that never really had strong evidence to back them.
Dr. Weimbs: Unfortunately, that has happened many times. Most nephrologists, I would say, have actually never really gone back and read this Brenner paper in detail. So I actually went back recently and said, “Okay, then let's read what exactly is in there,” and stumbled on something really interesting.
So the whole premise of this hypothetical paper was that ancient humans, when we were hunter gatherers, would have consumed food only every two days. So he just hypothesized we were on an intermittent fasting regimen throughout our lives, and that has to do with our luck in hunting. So the premise was ancient people ate every two days, and that would have spiked their kidney filtration intermittently every two days, and then things went back to normal.
In contrast, modern humans would eat food all day long (which is true), so our kidneys would hyper-filtrate all day long, and that's what's causing chronic kidney disease.
So there is probably a lot of truth to some of that premise, because I think ancestral humans didn't eat all day long. They didn't have breakfast, lunch, and dinner with snacks in between. So to me, the natural conclusion, from that premise, would be that you would treat kidney disease by putting people on an intermittent fasting regimen, [not limit protein intake specifically]?
NJ: Starting from that premise, that’s the conclusion [one would draw].
Dr. Weimbs: Exactly. But that wasn’t the conclusion of the paper. The conclusion was: if we eat protein every two days that’s okay, but if you eat protein all day long, it’s not okay—so let’s cut down protein intake. And that has become clinical practice, to say, “Okay, eat all day long, whatever you want, except protein.”
In other words, the paper Dr. Barry Brenner originally wrote involved speculation about the pattern and content of ancient human diets. Starting from the speculative but plausible premise that ancient humans were often unwittingly engaged in intermittent fasting, Brenner somehow drew the conclusion that eating “too much” protein was specifically harmful to kidneys. He did not draw the conclusion that people should stop eating all the time, and instead eat more intermittently. This would have been the logical conclusion, as Dr. Weimbs pointed out. But for some reason, Brenner focused in on protein intake. He then went on the write the medical textbook on kidney health, effectively laundering his hypothesis as a fact that then informed official clinical guidelines. For decades, nephrologists have recommended to millions if kidney disease patients that they restrict protein intake. This led to some unknown level of muscle wasting and emaciation in who know how many people.
To this day, many physicians still operate under a belief in Brenner’s hypothesis. After all, it’s textbook.
NJ: Wow. So it seems like kidney biology and nephrology have a long history of getting things pretty much backwards.
Dr. Weimbs: Yes, I think that's very, very true, unfortunately.
The biology of what does promote good kidney health is fascinating and offers people easily implementable solutions. Unfortunately, the nephrology communicated has yet to soak in the latest research. In private correspondence, Dr. Weimbs explained what he thought the key takeaway of the Brenner story is:
I think the punch-line of the Brenner story is that ancestral humans were in ketosis half their lives. So his argument should have been that being in ketosis is a good thing. However, he did not actually say or conclude that. Nearly all nephrologists are somehow convinced that ketosis is harmful to kidneys and they are very much against ketogenic metabolic therapy. If we could make them understand that their idol, Brenner, actually made a good argument on the renoprotective effect of ketosis, it might save some kidneys.
Kidneys, Hearts, Brains: Social influence as a major driver of scientific “progress”
Dr. Brenner’s hypothesis about the dietary causes of kidney disease echoes the story of Dr. Ancel Keys, whose “diet-heart hypothesis” infamously became enshrined in public policy. To this day, the diet-heart creed is still the dominant way of thinking about diet and heart health among cardiologists and public health institutions American Heart association. I previously wrote about the diet-heart saga here, based on a similar conversation I had with physician-scientist Dr. Orrin Devinsky.
What’s worth emphasizing about both of these historical examples is what did not happen. Brenner has a hypothesis about the effects of diet on kidney health. Keys had one about heart health. Each hypothesis had some amount of empirical support that could be pointed to, but there was no overwhelming preponderance of evidence or true scientific consensus. In the case of Ancel Keys’ diet-heart hypothesis, there were not only credible alternative hypotheses, but active human efforts that prevented the scientific process from working as we expect it to. As detailed here, there was an active suppression of data—studies went unpublished, scientists with opposing views were bullied, funding halted.
If you enjoy this content, try these M&M articles:
The Cholesterol Cult & Heart Mafia: How the process of science evolves into The Science™ of public policy
For both the case of Brenner and Keys, individuals with a special level of social influence were able to get their ideas promoted and adopted by mainstream institutions by means other than scientific merit. Their hypotheses were not deployed into some idealized “marketplace of ideas,” where scientific ideas compete solely on strength of evidence. The playing field is never level—scientific ideas arise from humans minds, inextricably caught up in webs of social influence. The momentum that any given hypothesis gains or loses is not strictly a function of its empirical support. A person’s position within a social status hierarchy—their position within institutions, ability to write textbooks, or (today) social media savvy—are all significant factors influencing whether a given idea “sweeps to fixation” and becomes recognized as consensus, textbook knowledge.
In genetic evolution, a selective sweep occurs when a set of genes quickly spreads through a population. This happens if they confer a strong reproductive advantage to the organisms housing them. In the realm of memetic evolution, combinations of ideas are housed and transmitted as narratives. Narrative transmission (“reproductive success”) is determined by whether or not a given individual believes they will receive social benefits from adopting and repeating the narrative. The ability of ideas to predict external reality (i.e. scientific merit) is just one of many factors influencing a narratives’ social success.
Has our scientific understanding of other organs been similarly led astray due to corrupting influence of social forces on the scientific process? It’s hard to know the extent to which this is happening, but there’s no doubt that it is. The brain is another organ worth pondering—an area of intense study, as well as stiff competition for prestigious research positions.
Our present understanding of neurodegenerative disease may be one area where we’ve been led far astray. In 2023, Dr. Marc Tessier-Lavigne resigned as Stanford University president amid a ongoing scandal in which multiple, high-profile papers from his lab were retracted. The retractions took place over twenty years after those papers were published, having influenced the flow of untold millions of dollars in grant money. There have even been numerous recent retractions of Nobel Prize-winning research. If anything, this seems to be becoming more common with time, as scientific disciplines “mature”—another awkward fact for the mythos of steady, inevitable scientific progress.
What other scientific myths may be animating human behavior today? What influential narratives might we be mistaking for textbook facts?
What will you eat today, and why?
To learn more about the topics covered in this essay, try these episodes of the Mind & Matter podcast: