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Portrait of Otto Warburg
Photo: Unknown author, http://www.nobelprize.org/nobel_prizes/medicine/laureates/1931 · Public domain via Wikimedia Commons

Nobel Prize in Physiology or Medicine · 1931

Otto Warburg

He found the iron enzyme that lets cells use oxygen and spotted cancer's hunger for sugar, the clue behind PET cancer scans.

The Nobel citation: “for his discovery of the nature and mode of action of the respiratory enzyme”
Born
October 8, 1883, Freiburg im Breisgau, Germany
Died
August 1, 1970, West Berlin, West Germany (now Germany)
Affiliation at the time
Kaiser-Wilhelm-Institut (now Max-Planck-Institut) für Biologie, Germany

Medicine prize

1931

Awarded alone.

Age that year

48years

Born in 1883.

Headline credited impact

240,000–810,000people benefited

Cancer patients whose planned care changed after an FDG-PET glucose scan. How it was built

Sources cited

26

Fact-checked September 24, 2026.

  • In 1918, at his mother's request, the family friend Albert Einstein wrote urging him to leave the army and return to research. He did.
  • The Nobel archive lists 51 nominations for him. Fellow laureate Otto Meyerhof nominated him six times.
  • Hospital FDG-PET cancer scans work because tumors gulp sugar, the habit Warburg measured in thin slices of tumor in the 1920s.
  • Nazi law classed him as half-Jewish, yet apart from a three-week removal in 1941 he led his institute through the war. Historians still debate why.
  • The name 'Warburg effect' for cancer's sugar habit was coined by the biochemist Efraim Racker in 1972, two years after Warburg died.

The breakthrough

Finding the iron enzyme that lets living cells use oxygen (1920s)

Every cell in your body burns food with oxygen to get energy, a process called cell respiration. A fire needs great heat to burn, so how do cells manage it at body temperature? Warburg suspected a catalyst, a helper molecule that speeds a reaction without being used up. The helper was far too scarce to isolate: by his estimate, its iron made up about one ten-millionth of a cell's mass. So he studied it indirectly. With a pressure gauge he adapted, now called the Warburg manometer, and thin slices of living tissue, he measured precisely how fast cells used oxygen. Cyanide and carbon monoxide, both of which grab onto iron, shut respiration down. Then came a clever trick. Light breaks carbon monoxide's grip, and different colors of light do so to different degrees. By measuring which colors best restarted breathing, he worked out the hidden enzyme's color spectrum without ever seeing it, like identifying a stranger from the shadow they cast. By 1928 he concluded it was a red iron pigment related to hemoglobin, the oxygen carrier in blood. Today it is known as cytochrome oxidase. Along the way he measured tumors, and in 1923 found that cancer tissue turns sugar into lactic acid many times faster than normal tissue, even when oxygen is plentiful. Scientists now call this the Warburg effect.[1],[3],[4],[6],[12],[26]

“Indeed, the ferment substance - though being so near to us - is, like the substance of the stars, inaccessible for us.”
Otto Warburg, Nobel Lecture, 10 December 1931, on why he had to study the respiratory enzyme indirectly, by its light spectrum, rather than isolate it (English translation published by the Nobel Foundation).[3]

What it meant for humanity

Warburg's work changed medicine mostly through tools and ideas that others built on. His measuring methods, the manometer and thin tissue slices, became standard laboratory tools for studying how cells turn food into energy, and Hans Krebs, a future Nobel laureate, trained in his lab from 1926 to 1930. In the 1930s he found that two small helper molecules carry hydrogen inside cells: one built around riboflavin (vitamin B2) and one around nicotinamide, a form of vitamin B3. The second, known today as NAD and NADP, works with about 150 enzymes. Its reduced form absorbs ultraviolet light, which let him follow enzyme reactions with a light meter. This optical test, later made commercial with Beckman Instruments, became a worldwide laboratory method, and hospital tests such as measuring alcohol in blood serum still rely on it. His most visible legacy is in cancer care. Because tumors take up far more sugar than most normal tissue, doctors can inject a radioactive sugar look-alike called FDG and watch where it collects with a PET scanner. FDG-PET, paid for by Medicare for some cancers since 1998, is now the main clinical PET test for finding tumors, staging them and checking whether treatment works. In a US registry of nearly 23,000 PET scans in people with known or suspected cancer, doctors changed their planned care after 36.5% of them. A UN survey puts nuclear medicine scans at roughly 40 million a year worldwide, and PET at about 17% of the scans it counted. And since the 2000s the Warburg effect has become a busy research field again, as scientists look for ways to attack cancer through its unusual metabolism.

  • FDG-PET cancer scans rely on tumors taking up extra glucose, the Warburg effect. The test became the leading clinical use of PET, used to find and stage cancer and to see whether treatment is working.[7],[13],[14]
  • In the first year of the US National Oncologic PET Registry, 22,975 scans in older Medicare patients, doctors changed their intended management after 36.5% of scans, and about 70% of planned biopsies were avoided.[15]
  • His optical test, built with Walter Christian in 1936, tracks the coenzyme NADH by its ultraviolet absorption. It spread worldwide and still underlies routine tests such as enzymatic blood-alcohol measurement.[6],[23]
  • He identified flavins and nicotinamide as the working parts of enzymes that shuttle hydrogen in cells. The NAD(P) coenzymes built on nicotinamide serve about 150 enzymes.[2],[6]
  • Researchers who worked in or visited his lab included future Nobel laureates Hans Krebs, Hugo Theorell, Fritz Lipmann and Severo Ochoa.[6]
  • Papers on the Warburg effect in cancer have multiplied since the 2000s, as researchers study how tumor metabolism is wired to growth signals and how to target it.[6],[12],[26]

Impact in numbers

Warburg's impact is mostly indirect but deep. His discovery of the iron-containing respiratory enzyme, and of the hydrogen-carrying coenzymes built from vitamins B2 and B3, is core textbook knowledge of how cells make energy. His optical test became a standard way to measure enzymes and still underlies routine laboratory tests. His 1920s finding that tumors devour glucose is the basis of FDG-PET, a key imaging test in cancer care. We model that FDG-PET changed the planned care of roughly 8 to 27 million cancer patients worldwide since 1998, and credit Warburg only 3%, because the scans also needed radiochemists, physicists, engineers and clinical researchers. We do not put numbers on his basic biochemistry or lab methods, since no honest figure exists. His cancer theory, pushed too far, has a downside too: it is still misused to sell false cures.

HealthFundamental science

Each number is the laureate’s credited share of a real-world outcome, cumulative to 2025. The whole outcome, the share of credit, and the reasoning are shown so you can check the arithmetic. Outcomes shared with other laureates are counted once on the impact page.

  • Low confidenceRippleModeledHealth

    Cancer patients whose planned care changed after an FDG-PET glucose scan

    240,000–810,000

    people benefited, credited share

    That is 3% of 8–27 million people benefited since 1998.

    How this number was built

    UNSCEAR: about 40M nuclear medicine scans a year worldwide (2009-18 surveys), 17% of them PET, so 6.8M PET a year; the US alone did 2.09M in 2018 (IMV). Scans: low = quadratic rise from 0 in 1998 (Medicare coverage) to 6.8M in 2018, then flat = 96M; high = linear rise, then +6% a year (US grew 10-12% in 2023-24) = 132M. FDG cancer share 0.70-0.85 (US: FDG 74% of scans; oncology about 90%) = 67M-112M. At 2.5 (low) or 1.5 (high) scans per patient (Gallach et al. assume at least 1) = 27M-75M patients. NOPR (US Medicare): plans changed after 36.5% of scans; use 30% (low) and 36.5% (high) = 8M-27M. Share 0.03: tumors' glucose hunger, which Warburg measured, is why FDG works, but FDG chemistry, PET physics, scanners, PET/CT and clinical trials by many others were essential.[13],[14],[15],[16],[17],[18],[19],[20],[21],[22]

    Sources: United Nations Scientific Committee on the Effects of Atomic Radiation; AuntMinnie.com; AuntMinnie.com; Diagnostic and Interventional Cardiology (DAIC), reporting IMV Medical Information Division data; AuntMinnie.com; IMV Medical Information Division, via PR Newswire; Journal of Clinical Oncology, via PubMed; Medical Science Monitor, via PubMed Central; Journal of Medical Imaging, via PubMed Central; Theranostics, via PubMed Central

The double edge

Warburg's discoveries were not used to hurt people, but his record has real shadows. He insisted until his death that damaged respiration is the prime cause of all cancer, and he brushed aside evidence about genes and viruses. Later work showed that most cancer cells have working mitochondria and that the metabolic shift usually follows genetic mutations. Misreadings of his idea still feed false cancer cures, including a so-called high-pH therapy with cesium salts that has caused dangerous heart rhythm problems and deaths. He also defended a wrong value in photosynthesis for decades. Ethically, he stayed in Nazi Germany and accepted protection from senior officials. He helped some Jewish co-workers find jobs abroad, but biographers say he did little to defend persecuted colleagues, and his accommodation with the regime angered scientists abroad. Historians also note that he performed no known unethical experiments and privately criticized some Nazi policies.

  • Moderate

    A cancer theory pushed too far

    In his 1956 Science paper and a 1966 lecture at Lindau, Warburg claimed that damaged respiration is the prime cause of all cancer. Later work showed that mitochondria work in most cancer cells and that the metabolic changes usually result from mutations in cancer genes. He was criticized for dismissing genes and viruses.[6],[7],[12],[24]

  • Moderate

    Misused to promote false cancer cures

    A 2026 review says misreadings of Warburg's hypothesis still fuel false claims about diet cures in books and social media, and underpinned so-called high-pH therapy with cesium salts. Of 20 published cases of people taking cesium, 16 of them as an alternative cancer treatment, five died.[24]

  • Moderate

    Staying on in Nazi Germany

    Warburg kept his institute throughout the Nazi years with protection from senior officials. Biographer Sam Apple judges that he did little to defend persecuted colleagues: he let a young Jewish researcher go in 1933, apparently under pressure, though he helped Jewish co-workers find jobs abroad and advised Hans Krebs to move to England. His acceptance of the regime's reclassification of his ancestry angered colleagues abroad.[6],[7],[8],[10]

  • Minor

    Wrong about photosynthesis for decades

    Warburg insisted that plants need only 3 to 4 particles of light to release one oxygen molecule. Robert Emerson measured 8 to 12, and Emerson's value proved correct despite Warburg's long challenges.[25]

Against the odds

Warburg grew up in comfort in Berlin, the son of a leading physicist, and for most of his career faced little personal discrimination. After 1933, though, his father's Jewish origins made him vulnerable. The Nazi regime drove Jews out of universities and state posts; Sam Apple counts about 2,600 scientists who left Germany, and the Kaiser Wilhelm Society was purged of its Jewish researchers. An early exemption for First World War veterans, foreign funding for his institute and, historians suspect, his value to the regime helped Warburg, a decorated veteran, keep his post. The 1935 Nuremberg Laws classed people with one or two Jewish grandparents as Mischlinge, neither German nor Jewish, and that is how the state saw him. His lifelong companion, Jacob Heiss, was a further risk, since the Nazis persecuted men accused of homosexuality; at one point someone denounced them. In 1941 he was removed as director. Within weeks he was reinstated after intervention from Hitler's Chancellery, and Hermann Göring had him reclassified as quarter-Jewish. Historians suspect that Hitler's fear of cancer made Warburg's research useful. He moved his lab out of bombed Berlin in 1943 and lost his equipment to Soviet troops in 1945. Several members of the wider Warburg family were murdered in the Holocaust. Warburg was protected rather than persecuted like most Jews, but his safety rested on the regime's whims.

  • 1935

    Persecution

    Under the 1935 Nuremberg Laws, which classed people with one or two Jewish grandparents as Mischlinge, the state treated him as half-Jewish. Biographer Sam Apple says protection for such people eroded after the war began, and Warburg's own position grew far more precarious in 1942.[7],[8],[11]

  • 1941

    Dismissal

    In 1941 he was removed as head of his institute. About three weeks later he was reinstated on orders from Hitler's Chancellery, and Göring had his ancestry reassessed as one-quarter Jewish.[6],[7],[9]

  • —

    Other

    He lived with his companion of some 50 years, Jacob Heiss. Biographer Sam Apple describes him as gay, another danger under the Nazis, and notes that someone wrote to Nazi authorities accusing the pair of homosexuality.[7],[8]

  • 1943

    War

    Allied bombing forced him to move his laboratory from Berlin to the countryside in 1943, and in 1945 Soviet forces confiscated its equipment.[6],[7]

Jewish background

Jewish fatherDistant from Jewish identity

His father, the physicist Emil Warburg, came from the old Jewish Warburg family; Emil's parents were Orthodox Jews, but he became a Protestant as an adult. His mother came from a Protestant South German family of officers and officials. Otto considered himself a German Christian, had no contact with the Jewish community, did not identify as Jewish and was buried in a Christian cemetery. Nazi law classed him as a first-degree Mischling (half-Jewish) because two of his grandparents were Jewish; after a 1941 crisis, Hermann Göring had him reclassified as quarter-Jewish. He meets this site's standard through his father.[6],[7],[8],[9]

Key dates

  1. October 8, 1883

    Born in Freiburg im Breisgau, Germany, the son of the physicist Emil Warburg and a Protestant mother.[1],[2],[6]

  2. 1906

    Earns a doctorate in chemistry in Berlin under Emil Fischer.[2],[6]

  3. 1911

    Earns a medical doctorate in Heidelberg under Ludolf von Krehl, after studying respiration in sea urchin eggs in Naples.[2],[6]

  4. 1913

    Joins the new Kaiser Wilhelm Institute for Biology in Berlin-Dahlem.[6]

  5. 1914

    Volunteers for the army and serves four years in an elite Prussian cavalry unit; he is wounded and awarded the Iron Cross, First Class.[2],[6],[7]

  6. 1918

    After a letter from Albert Einstein urging him back to science, returns to Berlin and is made a professor at the Kaiser Wilhelm Institute.[2],[6],[7],[10]

  7. 1923

    With Seigo Minami, finds that tumor tissue turns sugar into lactic acid far faster than normal tissue, the later Warburg effect.[6]

  8. 1928

    Concludes that the respiratory enzyme is a red iron pigment related to hemoglobin.[1],[4]

  9. December 10, 1931

    Wins the Nobel Prize in Physiology or Medicine for the respiratory enzyme, and becomes director of the new Rockefeller-funded Institute for Cell Physiology.[1],[2],[4],[6],[10]

  10. 1936

    With Walter Christian, shows that nicotinamide is the hydrogen-carrying part of a key coenzyme and develops the optical test.[6],[23]

  11. 1941

    Ordered out as director of his institute; weeks later he is reinstated through Hitler's Chancellery and reclassified as quarter-Jewish.[6],[7],[9]

  12. 1944

    Nominated for a second Nobel Prize by Albert Szent-Györgyi; claims that he was chosen but blocked by Hitler are unconfirmed.[5],[7]

  13. 1956

    Publishes On the Origin of Cancer Cells in Science, arguing that damaged respiration causes cancer.[6],[7]

  14. August 1, 1970

    Dies in West Berlin at 86, still at work in his institute.[1],[6],[7]

Sources

  1. 1.Otto Warburg - Facts · NobelPrize.org (Nobel Prize Outreach)
  2. 2.Otto Warburg - Biographical · NobelPrize.org (from Nobel Lectures, Physiology or Medicine 1922-1941, Elsevier, 1965), 1965
  3. 3.The oxygen-transferring ferment of respiration (Nobel Lecture, 10 December 1931) · NobelPrize.org, 1931
  4. 4.The Nobel Prize in Physiology or Medicine 1931 - Presentation Speech by E. Hammarsten · NobelPrize.org, 1931
  5. 5.Otto Warburg - Nominations · NobelPrize.org (Nomination Archive)
  6. 6.Warburg effect(s): a biographical sketch of Otto Warburg and his impacts on tumor metabolism (Otto AM, Cancer & Metabolism 4:5) · Cancer & Metabolism, via PubMed Central, 2016
  7. 7.Dr. Otto Heinrich Warburg: Survivor of Ethical Storms (Weisz GM, Rambam Maimonides Med J 6(1): e0008) · Rambam Maimonides Medical Journal, via PubMed Central, 2015
  8. 8.What a Gay, Jewish Scientist of the Nazi Era Has to Teach Us About Cancer (interview with Sam Apple by Andrew Silow-Carroll) · Jewish Telegraphic Agency / The Jewish Week, 2021
  9. 9.Why the Nazis allowed a Jewish cancer scientist to remain in Berlin during WWII (by Renee Ghert-Zand) · The Times of Israel, 2021
  10. 10.Otto Heinrich Warburg · Harnack House of the Max Planck Society
  11. 11.The Nuremberg Race Laws · United States Holocaust Memorial Museum, Holocaust Encyclopedia
  12. 12.Understanding the Warburg effect: the metabolic requirements of cell proliferation (Vander Heiden, Cantley and Thompson, Science 324: 1029-1033) · Science, via PubMed Central, 2009
  13. 13.History and future technical innovation in positron emission tomography (Jones and Townsend, J Med Imaging 4(1): 011013) · Journal of Medical Imaging, via PubMed Central, 2017
  14. 14.FDG uptake in cancer: a continuing debate (Peppicelli et al., Theranostics 10(7): 2944-2948) · Theranostics, via PubMed Central, 2020
  15. 15.Impact of PET/CT and PET alone on expected management of patients with cancer: initial results from the National Oncologic PET Registry (Hillner et al., J Clin Oncol 26(13): 2155-2161) · Journal of Clinical Oncology, via PubMed, 2008
  16. 16.UNSCEAR 2020/2021 Report, Annex A: Evaluation of medical exposure to ionizing radiation · United Nations Scientific Committee on the Effects of Atomic Radiation, 2022
  17. 17.PET Census: Slower But Continued Growth in PET Patient Studies (2008 to 2010) · Diagnostic and Interventional Cardiology (DAIC), reporting IMV Medical Information Division data, 2011
  18. 18.IMV: PET/CT drives PET scan volume to new heights · AuntMinnie.com, 2019
  19. 19.IMV: PET scan volume continues growing at steady pace · AuntMinnie.com, 2020
  20. 20.PET scan volumes continue to grow · AuntMinnie.com, 2024
  21. 21.Demand for PET Imaging Surges 12.2% in 2024, Straining Capacity at U.S. Facilities, IMV Report Finds · IMV Medical Information Division, via PR Newswire, 2025
  22. 22.Addressing Global Inequities in PET-CT for Cancer Management: A Statistical Model to Guide Strategic Planning (Gallach et al., Med Sci Monit 26: e926544) · Medical Science Monitor, via PubMed Central, 2020
  23. 23.The enzymatic analysis of alcohol (ethanol) in serum and plasma with the alcohol dehydrogenase reagent (Ialongo and Jones, Biochem Med 35(3): 030501) · Biochemia Medica, via PubMed Central, 2025
  24. 24.Intoxication by Self-administered Cesium Salts, the Clinical Impact of Questionable Research Output (Brouwer et al., Cardiovasc Toxicol 26: 10) · Cardiovascular Toxicology, via PubMed Central, 2026
  25. 25.On the evolution of the concept of two light reactions and two photosystems for oxygenic photosynthesis: A personal perspective (Govindjee, Photosynthetica 61: 37-47) · Photosynthetica, via PubMed Central, 2023
  26. 26.The Warburg Effect: How Does it Benefit Cancer Cells? (Liberti and Locasale, Trends Biochem Sci 41: 211-218) · Trends in Biochemical Sciences, via PubMed Central, 2016

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