The most important medical advance of the past century

Antibiotics revolutionized medicine, but it is likely that no single antibiotic caused as big of a drop in deaths as a simple over-the-counter medicine that you have probably taken it at some point without appreciating how revolutionary it is.  It treats the ailment that was the biggest killer in the world for thousands of years until sometime in the 1980s.  Guess what ailment it is:

  • Everyone gets it occasionally, including you.
  • It is an infectious disease that is caused by so many different pathogens that doctors rarely even try to figure out which pathogen is causing the disease.
  • It is particularly tragic because it mostly kills infants and children.
  • Largely due to a new treatment its death toll dropped from 5 million children annually in the early 1980s, to only 1.5 million in 2004 (WHO).
  • The treatment only costs pennies per day and can be produced at home by anyone with the most rudimentary ability to follow a recipe.
  • Although the new treatment has caused death rates to plummet, there is still a lot of work to be done and in 2008, it was still the world’s second leading cause of death in children under 5.
  • Although it rarely kills anyone in rich countries, in 2001 it was still the fourth biggest killer in total in developing countries.

The world’s biggest killer for all of history until the 1980s is…. drum roll… diarrhea!  Most Americans would never guess it because almost nobody dies from diarrhea in temperate nations like the US mostly due to improved sewage and water treatment which have prevented the spread of disease.  It is much harder to manage sanitation in poor, tropical nations, and there isn’t enough access to expensive intravenous treatment, so diarrhea remained the biggest killer in the world until a new treatment was developed in the 1970s which almost magically eliminates over 90% of diarrheal deaths for pennies per treatment.  The British medical journal, the Lancet called it, “potentially the most important medical advance this century,” but most people don’t even know what it is.

As an economist, I rarely teach something practical that could save a life, but I have used this treatment many times for my kids when they were little and for myself when afflicted with severe diarrhea while traveling in tropical nations.  It may have already saved your life when you were a child because it is the primary treatment for diarrhea in the US too.  It is called Oral Rehydration Therapy (ORT – but there are several other acronyms like ORS).  It is basically water with a fairly precise amount of salt and sugar.  That’s right salty sugar water is the most important medical advance of the 20th century!  The WHO estimates that ORT saved well over 60million people and it continues to save millions every year.

The basic formula:  Just mix up these ingredients and drink as much as you can to replace the fluids lost due to diarrhea.

  • 6 level tsp sugar (30 ml)
  • 1/2 tsp salt, (2.5 ml)
  • 1 litre (4.25 Cups) of clean water

Note that this is not the optimal formula, but it is almost as good as a professional formula and if you cannot purchase a professional version, it is probably good enough and certainly better than nothing.  It is very important to not mix in too much salt and sugar.  Too much salt and sugar is worse than not enough because it will increase dehydration and draw liquid out of the body instead of increasing absorption.  For example, sports drinks like Gatorade have too much sugar and not enough salts and will be as bad or worse than plain water.  ORT should taste only VERY slightly salty and slightly sweet like 1/3-strength juice. A proper ORT mix tastes a bit unpleasant, but the flavor should be very mild if it is mixed correctly.

I prefer using apple juice.  It tastes better and provides some potassium too.  Other juices like orange juice or grape juice are probably ok to substitute, but don’t look good if you are vomiting.  The basic apple juice recipe is:

  • 1C apple juice
  • 3C water
  • ½t salt

This treatment is largely responsible for the dramatic reduction in the number of children dying from diarrhea.  Diarrhea still causes nearly 1 in five childhood deaths  according to the World Health Organization and these deaths are mostly preventable if people had used ORT.  This treatment is so simple, the big problem with getting people to use it has been to convince them that something so trivial is really a miracle cure.  Historically, nobody was convinced that ORT could work until scientists figured out the mechanism of how diarrhea kills people.

People don’t literally get so ‘pooped’ that they die.  Diarrhea actually kills the same way that sweating too much could kill.  People die when they lose about 10% of their fluid.  Imagine that you had a single massive sweat gland that is going to produce 10 liters (2.6 gallons) of sweat over the next 24 hours.  It isn’t hard to imagine how that could be life threatening.  (A giant pimple might also come to mind at this point, and obviously a giant pimple on a gland that is pumping out two and a half gallons of fluid would be more than just socially damaging.)  There are two main lethal mechanisms:

  1. Dehydration
  2. Salt (electrolyte) depletion

To put 10 liters of fluid loss into perspective, most people drink less than 2 liters/day (about 8 cups) and pee less than 1.5 liters/ day, so it is easy to see how a loss of 10 liters of fluid could cause death from dehydration.  In addition, diarrhea pumps out salt and other electrolytes that are necessary for life.  An electrolyte shortage can directly cause death causing the heart, brain, or other vital organs to malfunction. Or an electrolyte shortage could indirectly cause death by weakening the immune system’s ability to fight infection.

Normally the intestines absorb more liquid than they excrete, but diarrhea turns the intestines into something like a giant sweat gland.  Both diarrhea and sweat glands are salty because they both work through osmotic transport.  The body’s cells move water across membranes using an osmotic salt pump.  For example, when the body wants to expel sweat, the cells in the sweat gland push salt out of the body. Then the salt attracts water from inside the body because osmotic pressure tries to equalize the salt concentrations.  The water then flows through the membranes and out of the body as a result.  I guess nobody tasted diarrhea to discover that it is a bit salty like sweat, but diarrhea pulls water out of the body using the same mechanism as a sweat gland and diarrhea is even saltier than ORT.  One significant difference between the sweat glands and the intestines is that the intestines also use sugars to pump water.  That is why ORT contains both sugar and salt.  The sugar is pulled the other way across your body’s membrane into your bloodstream and each sugar molecule pulls one sodium ion which pulls one bit of water.  This is why the formula must have an equal concentration of salt and sugar molecules for optimal functioning.  It doesn’t work if each molecule of salt isn’t paired with a sugar.

Research is currently being carried on to utilize these additive effects to develop a multi-component "Super ORS".

Because the intestines have a lot bigger capacity for moving fluid than the body’s sweat glands, the intestines can squeeze ten liters of fluid out of an adult body per day which is a dangerous amount of water and salt. ORT works by creating just the right amount of osmotic pressure in the intestines to push fluids back into the body to replenish both fluids and electrolytes.


There are many ancient traditions in India and elsewhere that prescribed similar solution as a home remedy, but without a precise ratio of salt and sugar, it was difficult to consistently replicate success. India has had a longstanding tradition of treating diarrhea by giving rice or coconut water with is fairly effective, but this traditional formula does not contain enough salt.  Sweden had a tradition of using a diluted carrot soup, but it didn’t always have the right ratio and often had too much salt. Without scientific understanding, the traditional remedies were often a little off and sometimes a lot off.  For example, more is not better:  If the solution has too much salt or sugar, it can be worse than plain water which is likely to be lethal.  There have been several failed attempts due to overly-concentrated solutions.   For example, in the US in the 1950s powdered banana was mixed with water with varying degrees of success.

Western medicine ignored the ancient wisdom until researchers provided both an understanding of the biological mechanism for why it works along with numerous clinical experiments showing that it worked to save lives. Medical doctors were unconvinced by the multiple studies that showed how well ORT worked until they also understood the osmotic mechanism of how diarrhea works.  Unfortunately, for many years the scientists who discovered the osmotic mechanism didn’t think about how their discovery might have practical applications for diarrhea treatment and the clinical scientists who were testing various ORT formulas didn’t read the biology.  Nobody combined the theory about the mechanism with the experimental evidence until the 1970s and once the two were combined, doctors were finally convinced and ORT finally caught on.

In hindsight, you can see a mountain of evidence had been accumulating before mainstream medicine finally caught on, but the quality of medical “science” was horrifically bad before the 1970s, so it was hard for practitioners to know what was good science and what was bad.  The gold-standard in medical research is the randomized-controlled trial (RCT), but before the late 1960s, there were almost zero RCTs per year and most medical research was junk.  Even among RCTs, most medical research is still contradictory or misleading, so in an era before RCTs it was exceptionally hard to know what research to believe.  RCTs were almost unheard of until the 1970s.


Once medical professionals understood how ORT worked, they finally believed the research showing that it did indeed work. With both an understanding of the mechanism they finally believed the clinical evidence and ORT rapidly gained widespread acceptance in the 1980s.  Salty sugar water just didn’t seem like a technological breakthrough that could be a magic bullet.  The basic ORT formula sounds like something out of an ‘old wives tale’ that might be followed with the extract from the boiled toes of a newt.

Before ORT, the conventional scientific theory had been that diarrheal deaths were merely caused by the inability of the gut to absorb fluid.  That wouldn’t be nearly as big of a problem as the reality.  Diarrhea kills people by turning the intestine into something like a giant sweat gland that rapidly extracts fluid and electrolyte from the body.  Based on the old theory, IV treatment had been developed in 1920s and doctors thought that oral nutrients should actually be withheld from patients to help stop the flow of diarrhea and give the intestines a rest.  Even though the theory was faulty, the IV treatment worked well enough that it was not much problem that patents weren’t given enough to drink.  The success with expensive hospital IV treatment made it hard for medical science to change their thinking.  IV treatment seemed more scientific and technical than the traditional remedies like carrot soup or coconut water that work like ORT and it was easier to standardize the IV formula. It was also a lot more profitable, but poor people cannot afford it and ORT works as well or better for most diarrhea cases.  A big advantage of ORT over IV therapy is that IVs can cause lethal infections, particularly in hospital settings.  ORT really is safer for most patients which is why it is the preferred treatment in rich countries today too.

Unfortunately, even though ORT is an incredibly cheap and effective way to save lives, it still isn’t being used nearly enough.  The biggest problem is educating doctors and patients about how well it works.  One problem with cheap interventions like ORT is that it isn’t very profitable because it isn’t patented and there is little incentive for markets to disseminate it around the world to where it is needed most.  The Global Healthcare Information Network estimates that:

Only 1 in 10 children with diarrhoea in India receive increased fluids to prevent death from dehydration. Almost 4 in 10 receive less to drink than normal, thereby tragically increasing their risk of death. By contrast, more than 1 in 3 are inappropriately given antibiotics, which are not generally recommended for childhood diarrhoea. Almost half of children with diarrhoea in India are given little or no food, contrary to WHO recommendations. A thousand children die needlessly from diarrhoea every day in India alone, due to basic errors in care from parents and health workers.

And ORT use is much better in India than in many other nations.  Although ORT is an incredible success story that very few people have heard about, there is much work yet to be done:


Age-standardised disability-adjusted life year (DALY) losses from Diarrheal diseases per 100,000 inhabitants.

Posted in Development, Health, Millionaire Superheroes

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