The surprising cause of stomach ulcers - Rusha Modi

3,698,104 views ・ 2017-09-28

TED-Ed


Please double-click on the English subtitles below to play the video.

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In 1984, an enterprising Australian doctor named Barry Marshall
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decided to take a risk.
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Too many of his patients were complaining of severe abdominal pain
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due to stomach ulcers,
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which are sores in the lining of the upper intestinal tract.
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At the time, few effective treatments for ulcers existed,
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and many sufferers required hospitalization or even surgery.
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Desperate for answers,
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Dr. Marshall swallowed a cloudy broth of bacteria
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collected from the stomach of one of his patients.
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Soon, Dr. Marshall was experiencing the same abdominal pain,
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bloating,
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and vomiting.
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Ten days later, a camera called an endoscope
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peered inside his insides.
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Marshall's stomach was teeming with the same bacteria as his patient.
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He'd also developed gastritis, or severe inflammation of the stomach,
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the hallmark precursor of ulcers.
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Dr. Marshall's idea challenged
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a misconception that still persists to this day:
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that ulcers are caused by stress,
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food,
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or too much stomach acid.
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Marshall thought the culprit was bacterial infections.
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Initially, his idea was considered crazy
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by the brightest medical minds on the planet.
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But in 2005, he and Dr. Robin Warren received the ultimate validation
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when they were awarded the Nobel Prize for medicine.
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Our stomachs are J-shaped organs with surprisingly intricate ecosystems
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awash in hormones and chemicals.
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The stomach is under constant attack by digestive enzymes,
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bile,
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proteins,
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microbes,
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and the stomach's own acid.
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In response, it produces bicarbonate,
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mucus,
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and phospholipids called prostaglandins
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to maintain the integrity of its own lining.
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This delicate balance is constantly regulated
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and referred to as mucosal defense.
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Since the mid-1800s, doctors thought stress alone caused most stomach ulcers.
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Patients were given antidepressants or tranquilizers
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and told to visit health spas.
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This belief eventually shifted to the related notion of spicy foods
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and stress as culprits.
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Yet no convincing study has ever demonstrated that emotional upset,
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psychological distress,
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or spicy food
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directly causes ulcer disease.
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By the mid-20th century, it was widely accepted that excess hydrochloric acid
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prompted the stomach to eat itself.
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Fervent proponents of this idea were referred to as the acid mafia.
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The biggest hole in this theory was that antiacids only provide
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temporary relief.
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We now know that some rare ulcers
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are indeed caused by too much hydrochloric acid.
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But they make up less than 1% of all cases.
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Dr. Marshall and Dr. Warren pinpointed a spiral-shaped bacteria
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called Helicobacter pylori, or H. pylori, as the real offender.
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H. pylori is one of humanity's oldest and most frequent companions,
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having joined us at least 50,000 years ago,
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and now found in 50% of people.
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Previously, we thought the stomach was sterile
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on account of it being such an acidic, hostile environment.
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Yet H. pylori survives the acidic turmoil of the stomach
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with a variety of features that disrupt mucosal defense in its favor.
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For example, it produces an enzyme called urease
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that helps protect it from the surrounding gastric acid.
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H. pylori can make over 1,500 proteins,
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many of which are dedicated to maximizing its virulence.
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We still have unanswered questions,
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like why specific people develop ulcers at particular times.
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However, we do know individual genetics,
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other medical problems,
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use of certain medications,
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smoking,
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and the genetic diversity of Helicobacter strains all play a role.
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In particular, certain pain medications used to reduce inflammation in joints
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have been discovered to work with H. pylori
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to create more severe stomach ulcers.
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Dr. Marshall ended up being fine after his famous, albeit dangerous, experiment.
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He ingested a course of antibiotics similar to the ones taken now for ulcers.
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To be treated by simple antibiotics is a modern triumph
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for a disease that previously needed surgery.
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Marshall's work also reminded us that scientific progress is not always smooth.
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But there's value in trusting your proverbial,
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and sometimes literal, gut.
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