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'Low carb downunder' conference
 

'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.

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

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  • Eg. vitamin D. Plausible biological mechanism, consistent studies.Essentially inductionist principles. Critique: Rely heavily on the subjective judgement of the reviewer. Temporality particularly important (prospective studies stronger). Expanding scientific literature makes almost all plausible hypotheses supported.
  • Important, because in a prominent publication summarising findings, not one mention of the health effects of fructose was mentioned.
  • How much sugar do you think Nzers eat on average?
  • Why the about face????

'Low carb downunder' conference 'Low carb downunder' conference Presentation Transcript

  • Has nutrition research helped us with our food choices? Simon Thornley (Epidemiologist) University of Auckland
  • Summary What is science/epidemiology? A brief history of human nutrition I get involved… diversion into tobacco Food addiction? What next?
  • My view Yes, but many nutrition scientists are not listening to the data Fructose, sugar, carbohydrates are often overlooked
  • What is science or research? “In God we trust, all others bring data”  William Edward Deming “First establish the facts, then seek to explain them”  Aristotle
  • Science Anarchistic; consensus not useful Hypothesis and argument Disproof over proof Uncertainty over absolutes Integration
  • A basic epidemiological study… Disease Subjects What we eat Focus on statistical over biological evidence…
  • Error… Many contradictory studiesNot included in CI or p-value Accounted for by 95%[Quantitative bias analysis] Error confidence interval and p-value Selection bias recruitment %Information Systematic Random biasAccuracy of measures? Unmeasured False +ve False –ve ~5% ~10 to 20% confoundingRCT? From literature?
  • Confounding… Sugar consumption Coronary Heart Dental caries Disease
  • Bradford-Hill Criteria Strong  RCT better than association? observational study Consistent?  Makes sense Does cause come before effect? More exposuremore disease?
  • Salt restriction Salt restriction ↓ blood pressure Observational studies show both ↑ and ↓ survival (unmeasured confounding) Only randomised study shows benefit in group that didn’t restrict salt. Taylor, R. S., Ashton K. E., T. Moxham, L Hooper, and S. Ebrahim. "Reduced Dietary Salt for the Prevention of Cardiovascular Disease." Cochrane Database of Systematic Reviews, no. 7 (2011). http://www.mrw.interscience.wiley.com/cochrane/clsysrev/articles/CD009217/frame.html .
  • Is the idea falsifiable?HOW DOES SCIENCE GOWRONG?
  • How it works in theory… Idea Experiment Interpret New Idea Generate Test Inferences from Refinehypothesis hypothesis experiment hypothesis
  • In reality…? Experiment Interpret New Idea Generate Test Inferences from Ideahypothesis hypothesis experiment Refine hypothesis
  • Some history…NUTRITION IDEAS OVER THELAST 100 YEARS…
  •  Museum photo…
  •  Dairy photo
  • 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 English speaking countriesTaubes G. The Diet Delusion. New York: Vermilion; 2007.
  • Brain washing?THE ACCEPTED STORY
  • Nutrition to the rescue… A–B=CA = Energy in (food)B = Energy out (burned, metabolism)C = Energy stored (as fat)Cause↑A/↓B→↑C – obesigenic environment (↑energyin/ reduced energy out)
  • What’s ok...THE GOOD!
  • It’s not OK... Ever!THE BAD
  • http://longwhitekid.files.wordpress.com/2011/08/anchor-best-new-zealand-butter-380h-x-270w-heavy-card-21.jpg
  • Salt
  • WE ALL LIVED HAPPILYEVER AFTER?
  • AN ALTERNATIVE VIEWEMERGES…
  • My thoughts on obesity…Medical training Public Health Research ResearchTraditional Tobacco Similarities Critique ofNutritional theory addiction between energy density- Energy density obesity and Focus on sugar smoking1994 2005 2007 2011
  • Why does a smoker smoke?
  • Withdrawal Symptoms Duration (weeks) Irritability <4 Depression <4 Restlessness <4 Poor concentration <2 Increased appetite >10 Craving to smoke >2
  • Automatic behaviour Rational Automatic Addiction breathing Automatic, behaviour withdrawal, harm Mid brain/brain Cortex stem
  • Subconscious learning… Withdrawal discomfort Puff cigarette Nicotine metabolised Withdrawal More relief puffs
  • How do cigarettes work...?
  • FOOD ADDICTION?
  • Carbohydrate?
  • Eating and addiction? Atkins Diet An executive who had tried obesity surgery, laxatives, diets, everything…“Often I would shake until I could putsome sugar in my mouth”
  •  “Ihad an hour’s drive from my office to my home, and I knew every restaurant, candy machine and soft drink dispenser”
  • What about glucose? Is refined starch the same as nicotine? Are low GI foods the obese person’s equivalent to a smoker’s nicotine patch or gum?
  • Bread: white v. wholegrain
  • Glucose: glycemic index?
  • What about sugar? Sugar is actually low/moderate GI
  • I TAKE A LOOK AT SUGAR?
  • The medical gurus say sugar isOK? “Excess sucrose has largely been exonerated as an important dietary factor in the aetiology of type-2 diabetes...”J. I. Mann and A. S. TruswellDiseases of overnourished societies and the need for dietary change: in theOxford Textbook of Medicine, 4th Edition. Postprandial glycemia (GI) used to exonnerate sugar…
  • Sugar: traditional views 30% increase over last 30 yearsPopkin BM, Nielsen SJ. The sweetening of the worlds diet. Obesity Research 2003;11(11):1325-32. “Empty calorie”Nestle M. Soft drink "pouring rights": marketing empty calories to children. Public Health Reports 2000;115(4):308-19. Fructose not mentioned Something is missing?
  • Update... AHA turns around. “Fructose... has been indirectly implicated in the epidemics of obesity and type 2 diabetes”Circulation 2009;120;1011-1020
  • Fructose: what has changed? GI ignores fructose Sweeter than glucose Linked to:  Gout, diabetes, weight gain, metabolic syndrome  Hypertension, rotten teeth  High triglycerides, dyslipidaemia, CVD Tends to ↑ hungerJohnson, R.J., et al., Hypothesis: Could Excessive Fructose Intake and Uric Acid Cause Type 2 Diabetes? Endocr Rev, 2009. 30(1): p. 96- 116.Segal, M.S., E. Gollub, and R.J. Johnson, Is the fructose index more relevant with regards to cardiovascular disease than the glycemic index? European Journal of Nutrition, 2007. 46(7): p. 406-17.
  • What about saturated fat? Recent summaries  no association with heart disease.Skeaff CM, Miller J. Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Ann Nutr Metab 2009;55:173–201Mente A, de Koning L, Shannon HS, Anand SS (April 2009). A systematic review of the evidence supporting a causal link between dietary factors and coronary heart disease. Arch. Intern. Med. 169 (7): 659–69.
  • Food addiction: evidence Addiction pathways Eating is automatic Rats  sugar induces withdrawal; not fat.
  • In the headlines…
  • My inbox... “For three weeks I cut all sugar and flour… then…  mood swings…,  depression…,  stomach pain…,  joint and muscle pain…,  the shakes….”
  • “People who knew me started thinking I washiding a drug problem.”
  • Overeater’s Anonymous “When you are addicted to drugs you put the tiger in the cage to recover; When you are addicted to food, you put the tiger in the cage, but take it out three times for a walk” Kerri-Lynn Murphy Kriz
  • Critique: Academia “Any addictive … hypothesis cant explain the rise that weve seen over the last … 30 years of obesity.”Prof. Boyd Swinburn, Professor of Population Health, Deakin University 13 Jan 2009
  • SO WHAT?
  • Synopsis Nutrition focuses on energy not hunger Low fat idea predates obesity epidemic Sugar intake continues to ↑ Likely subtle addiction Likely cause of major risk factors for heart disease Many nutrition researchers stuck in energy paradigm (cf. some pop science)
  • More details
  • Thank you!Slides and my articles areavailable at:www.slideshare.net/sithor