Minnesota Coronary Experiment

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The Minnesota Coronary Experiment was the first large randomized controlled trial to investigate a targeted form of therapy. The study was planned and carried out by the American nutritionists Ivan Frantz (1916-2009) and Ancel Keys (1904-2004). The results of the study, which ended in 1973, were only published posthumously after more than 40 years. The initiators of the study wanted to prove that a reduction in saturated dietary fats reduces the cardiovascular risk . However, the results of the study showed the opposite. However, the data were not published by the initiators during their lifetime.

Scientific background

Cohort studies in the USA ( Framingham Heart Study and others) and the international seven-country study indicated that saturated dietary fats and elevated cholesterol levels significantly increased the risk of cardiovascular disease and premature death. To further corroborate this assumption, Ivan Frantz and Ancel Keys, founders of the seven-country study, initiated a large-scale clinical trial in Minnesota . The therapeutic replacement of saturated dietary fats with foods with a naturally high or artificially increased proportion of linoleic acid was planned .

execution

The study was planned as a randomized , double-blind study from 1966 . Recruitment began in 1968. It included 9,423 men and women from seven nursing homes and psychiatric hospitals. The study ended in 1973. The patients in the experimental group received a comprehensive diet change in which products with a high percentage of saturated fat were replaced by those with less saturated but more unsaturated fat (especially linoleic acid). The control group retained their original diet. A test duration of 41 to 56 months was planned. About 75% of the participants dropped out of the study before the end of one year, primarily because they were released from inpatient psychiatric treatment.

Results

Replacing saturated with unsaturated fat resulted in a greater reduction in cholesterol levels, but no benefit in terms of overall mortality. Patients over 65 years of age even died faster in the test group than in the control group. The more the patients in the test and control groups lowered their blood cholesterol levels, the higher their risk of death.

criticism

The test series was carried out according to the plan and completed in 1973, but only in small excerpts were published many years later as a conference contribution and doctoral thesis, but not as a classic paper. The results of the seven-country study and other cohorts were widely accepted until the 1990s and formed the basis for internationally applied dietary recommendations; The focus was on avoiding saturated fats. The 1973 Minnesota Coronary Experiment contradicts these findings. However, the study initiators decided not to publish the results.

Raw data and evaluations of the study were found by chance in the basement of Ivan Frantz in 2011 and were therefore only accessible to the public after the death of the founder of the study. The rediscovery of the study and the controversial results were widely discussed internationally, especially in the context of the conflicts of interest surrounding the proponents of the “Diet Heart Hypothesis”. A meta-analysis from 2015 found no influence from saturated fatty acids, but one from trans fatty acids .

literature

  • T. Beinortas, KR Mahtani, D. Nunan: Revisiting the diet-heart hypothesis: critical appraisal of the Minnesota Coronary Experiment. In: BMJ. Volume 357, 06 2017, p. J2108, doi : 10.1136 / bmj.j2108 , PMID 28572081 .
  • CM Skeaff, JI Mann: Diet-heart disease hypothesis is unaffected by results of analysis of recovered data from Minnesota Coronary Experiment. In: Evidence-based medicine. Volume 21, number 5, 10 2016, p. 185, doi : 10.1136 / ebmed-2016-110486 , PMID 27559090 .
  • MA Denke, ID Frantz: Response to a cholesterol-lowering diet: efficacy is greater in hypercholesterolemic subjects even after adjustment for regression to the mean. In: The American journal of medicine. Volume 94, Number 6, June 1993, pp. 626-631, doi : 10.1016 / 0002-9343 (93) 90215-b , PMID 8506889 .

Individual evidence

  1. ↑ Ivan D. Frantz Obituary. In: legacy.com. Retrieved May 11, 2020 .
  2. ↑ Christopher E. Ramsden, Daisy Zamora, Sharon Majchrzak-Hong, Keturah R. Faurot, Steven K. Broste: Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968-73) . In: BMJ . tape 353 , April 12, 2016, ISSN  1756-1833 , doi : 10.1136 / bmj.i1246 , PMID 27071971 .
  3. ^ ID Frantz, EA Dawson, PL Ashman, LC Gatewood, GE Bartsch: Test of the effect of lipid lowering by diet on cardiovascular risk. The Minnesota Coronary Survey . In: Arteriosclerosis: An Official Journal of the American Heart Association, Inc. Band 9 , no. 1 , January 1989, ISSN  0276-5047 , p. 129–135 , doi : 10.1161 / 01.atv.9.1.129 .
  4. ↑ Minnesota Coronary Experiment - Trying To See In A Blizzard? In: BostonHeartDiagnostics.com. May 9, 2018, accessed May 11, 2020 .
  5. ^ Peter Whoriskey: This study 40 years ago could have reshaped the American diet. But it was never fully published. In: washingtonpost.com. April 13, 2016, accessed May 11, 2020 .
  6. ↑ Editorial Board: The heretical Minnesota heart study: When science stops asking questions. In: chicagotribune.com. April 29, 2016, accessed May 11, 2020 .
  7. ↑ Eva Obermüller: “Good” fat - not that healthy at all? In: orf.at. April 13, 2016, accessed May 11, 2020 .
  8. ↑ expert reaction to study on vegetable oil, cholesterol levels, and risk of heart disease. In: ScienceMediaCentre.org. April 12, 2016, Retrieved May 11, 2020 (American English).
  9. ↑ Petra Plaum: Too much of a good thing? Plant oils rich in linoleic acid could also be bad for the heart in large amounts. In: medscape.com. May 6, 2016, accessed May 11, 2020 .
  10. ^ RJ de Souza, A. Mente, A. Maroleanu, AI Cozma, V. Ha, T. Kishibe, E. Uleryk, P. Budylowski, H. Schünemann, J. Beyene, SS Anand: Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. In: BMJ. Volume 351, August 2015, p. H3978, doi : 10.1136 / bmj.h3978 , PMC 4532752 (free full text).