'Low carb downunder' conference

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These are the slides I presented at the 'low carb downunder' conference in Sydney on the 24th of November 2012.

Transcript of 'Low carb downunder' conference

  • 1. Has nutrition research helped us with our food choices? Simon Thornley (Epidemiologist) University of Auckland

2. Summary What is science/epidemiology? A brief history of human nutrition I get involved diversion into tobacco Food addiction? What next? 3. My view Yes, but many nutrition scientists are notlistening to the data Fructose, sugar, carbohydrates are oftenoverlooked 4. What is science or research? In God we trust, all others bring data William Edward Deming First establish the facts, then seek toexplain them Aristotle 5. Science Anarchistic; consensus not useful Hypothesis and argument Disproof over proof Uncertainty over absolutes Integration 6. A basic epidemiological studyDiseaseSubjectsWhat we eat Focus on statistical over biological evidence 7. Error Many contradictory studiesNot included in CI or p-value Accounted for by 95%[Quantitative bias analysis] Errorconfidence interval andp-valueSelection bias recruitment %Information Systematic RandombiasAccuracy of measures? UnmeasuredFalse +ve False ve~5%~10 to 20% confoundingRCT? From literature? 8. ConfoundingSugar consumption Coronary Heart Dental cariesDisease 9. Bradford-Hill Criteria Strong RCT better thanassociation?observational study Consistent? Makes sense Does cause comebefore effect? Moreexposuremoredisease? 10. Salt restriction Salt restriction blood pressure Observational studies show both and survival (unmeasured confounding) Only randomised study shows benefit ingroup that didnt restrict salt. Taylor, R. S., Ashton K. E., T. Moxham, L Hooper, and S. Ebrahim. "Reduced Dietary Salt for the Prevention of CardiovascularDisease." Cochrane Database of Systematic Reviews, no. 7 (2011).http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD009217/frame.html . 11. Is the idea falsifiable?HOW DOES SCIENCE GOWRONG? 12. How it works in theoryIdea ExperimentInterpret New Idea GenerateTestInferences from Refinehypothesishypothesisexperiment hypothesis 13. In reality? ExperimentInterpret NewIdea GenerateTestInferences from Ideahypothesishypothesisexperiment Refine hypothesis 14. Some historyNUTRITION IDEAS OVER THELAST 100 YEARS 15. Museum photo 16. Dairy photo 17. What happened in the 1960s? Diet-heart hypothesis Heart disease caused by saturated fat Response: reduce fat (sugar or carb.) Cheap sugar (HFCS in USA) American Heart Assoc other Englishspeaking countriesTaubes G. The Diet Delusion. New York: Vermilion; 2007. 18. Brain washing?THE ACCEPTED STORY 19. Nutrition to the rescueAB=CA = Energy in (food)B = Energy out (burned, metabolism)C = Energy stored (as fat)CauseA/BC obesigenic environment (energyin/ reduced energy out) 20. Whats ok...THE GOOD! 21. Its not OK... Ever!THE BAD 22. http://longwhitekid.files.wordpress.com/2011/08/anchor-best-new-zealand-butter-380h-x-270w-heavy-card-21.jpg 23. Salt 24. WE ALL LIVED HAPPILYEVER AFTER? 25. AN ALTERNATIVE VIEWEMERGES 26. My thoughts on obesityMedical training Public Health Research ResearchTraditionalTobacco Similarities Critique ofNutritional theory addiction betweenenergy density- Energy density obesity andFocus on sugar smoking199420052007 2011 27. Why does a smoker smoke? 28. Withdrawal Symptoms Duration (weeks) Irritability