Of Cows and Men: Reviewing the Link Between Dairy Fat and Human Health

Transcription

1 Of Cows and Men: Reviewing the Link Between Dairy Fat and Human Health The Times, They Are A Changing To keep in mind: what 100% of experts believe and recommend usually changes over time Thomas Kuhn Eduardo Rico, Ph.D., and Daniel Rico, Ph.D. History of a Changing Perception A brief history of fat And then

2 Cardiovascular disease The Fear of Fats Excess weight gain and obesity The Diet Heart Hypothesis: A Hypothesis The 6 Country study Source: The New York Times, 2013 Father of the lipid hypothesis! Premises of the Diet Heart Hypothesis Fooling Ourselves? Dietary Saturated Fatty Acids A Serum (bad) Cholesterol B C? When tested rigorously, claims from observational studies fail to replicate findings 80% of the time. Coronary heart disease and deaths Young and Karr, 2011

3 The strength of evidence Causality! Randomized Trials of Disease Outcomes Prospective Cohorts of of Disease Outcomes Randomized Trials of Physiologic Measures/Risk Factors Retrospective Case Control Studies of Disease Outcomes Animal Studies Ecologic Studies Prevalence Studies Case Series/Case Reports Micha and Mozzafarian, 2010 Were the Dietary Fat Guidelines Backed by Good Evidence? A Big Fat Problem!

4 And then this Happened A Wise Choice? Fluid Milk Consumption Trends Bovine Milk Substitutes Today Source: USDA, Economic Research Service. 2012; 2018.

5 Was the Problem Solved? Was the Problem Solved? Although the rates of Death attributable to CVD have declined in the United States, the burden remains high % prevalence of Obesity, USA adults y.o. 2X increase in 30 years McGovern report Both (20-74, y) Men (20-74, y) Women (20-74, y) From: Prevalence and Trends in Obesity Among US Adults, JAMA. 2002; 288(14): Markers of Cardiovascular Disease The good and the not so good.. Getting the Fats straight Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides LDL particle size distribution Total / HDL cholesterol Triglyceride / HDL cholesterol

6 % of dietary energy Removing Dairy Fat from the Diet A Randomized Controlled Trial 50% CHO AAD, 14.1 AAD Average American +8%CHO Step I diet, %CHO Step II diet, 6.2 Step I diet Step II diet Reduced Reduced dairy fat I dairy fat I Federal American Heart Association Fat % Saturated fat % Monounsaturated fat % Lefevre et al., 2005 Mmol Lefevre et al., 2005 Removing Dairy Fat from the Diet Reduced Bad Cholesterol...but LDL-cholesterol Cholesterol * 1.00 * * 0.95 AAD Step I diet Step II diet Average Reduced Reduced American dairy fat I dairy fat II Mmol HDL-cholesterol Cholesterol AAD Step I diet Step II diet Average Reduced Reduced American dairy fat I dairy fat II * Removing Dairy From the Diet Increased CVD Risk Mmol/Mmol Total Total:HDL / HDL-cholesterol Triacylglycerol Triglycerides 1.3 * * 1.2 * * Mmol Cardiovascular Disease AAD Step I diet Step II diet Average Reduced Reduced American dairy fat I dairy fat II 1.0 AAD Step I diet Step II diet Average Reduced Reduced American dairy fat I dairy fat II Lefevre et al., 2005

7 Saturated fats Do Not Increase Cardiovascular Disease Risk Saturated fats Do not Increase Cardiovascular Disease Risk Relative risks for coronary outcomes in prospective cohort studies of dietary fatty acid intake. Meta-analysis of 21 prospective cohorts, n >340,000 subjects CVD, CHD inclusive of stroke: RR 1.00 [0.89, 1.11] Meta-analysis of 78 prospective cohorts and RCTs, with ~ 650,000 participants Siri Tarino et al., 2010 Chowdhury et al Saturated fats Do not Increase Cardiovascular Disease Risk Relative risks for coronary outcomes in prospective cohort studies of dietary fatty acid intake. Major CVD and Mortality Across the Continents The PURE study. Only Whole fat dairy Meta-analysis of 78 prospective cohorts and RCTs, with ~ 650,000 participants 17:0 (found in dairy) intake was associated with 23% reduction in CVD risk Chowdhury et al Dehghan et al., 2018

8 Major CVD and Mortality Across the Continents The PURE study. Does Fat Make Fat? Only Whole fat dairy Higher dairy consumption was associated with lower risks of mortality and cardiovascular disease, particularly stroke Dehghan et al., 2018 Gary Taubes, 2002 Does Dairy Increase Body Weight? Study ID Body Weight WMD 95% CI (kg) Weight (%) Does Dairy Increase Body Fat % Study ID Body fat WMD 95% CI (kg) Weight (%) Dairy consumption does not change risk of body weight gain Favors dairy Favors control Meta-analysis of 29 RCTs with 2,101 participants. Chen et al et al., 2012 Dairy consumption does not change risk of body fat gain Favors dairy Favors control Chen et al., 2012 Metaanalysis of 29 RCTs with 2,101 participants.

9 Could Carbs be the Enemy on your Plate? If not Fat, then What?! A Global Sugar Cult The Yudkin/Sugar Fight Fructose intake, % of total calories Fructose consumption raises circulating triglycerides and dysregulates hunger/satiety signals Vos et al., 2008; Teff et al. 2004

10 Milk Fat Intake & the Risk of Incident Diabetes Mellitus 2 large prospective cohorts Use of dairy intake markers in plasma 3,333 adults followed for 15 years Adjustments for lifestyle differences in multivariate analysis Hazard ratio Hazard ratio C15:0 P = C16:1 trans P < Hazard ratio Hazard ratio C17:0 P = 0.03 C14:0 P = 0.48 Adapted from Yakoob et al., 2016 Plasma FA, % of total FA Plasma FA, % of total FA The Fear of Fat is Melting Away The Fear of Fat is Melting Away

11 Summary and Final Thoughts No good evidence that dietary fats including dairy cause CVD, obesity, and chronic diseases: The fear of fats seems unjustifiable Heavy focus on dietary fats has been generally limited in predicting clinical outcomes, and arguably counterproductive. Higher quality evidence (prospective and randomized control trials) suggests dairy may be protective. Summary and Final Thoughts Can dairy products help combat the spread of chronic diseases? Of Cows and Men: Reviewing the Link Between Dairy Fat and Human Health Policy and guidelines The need to address bias Eduardo Rico Thank you!

12 A Global Sugar Cult Fructose intake, % of total calories Glucose Triglycerides Fructose Grhelin Fructose Consumption Dysregulates Appetite Glucose Fructose Glucose Leptin Fructose Vos et al., 2008; Teff et al Teff et al Some Saturated Fatty Acids Found in Dairy Fat Reduce CVD Risk Δ Total:HDL cholesterol * 0.05 C12:0 C14:0 C16:0 C18:0 Ratio increase % of energy intake from CHO replaced with FA Mensik et al., 2003 Carbohydrates Raise Small LDLs Krauss et al., 2003

13 New Evidence is Shifting Minds.. Cardiovascular Disease Risk in Individuals with the Highest Milk/Dairy Consumption Disease Relative Risk (95% CI) Ischemic heart disease 0.84 ( ) Stroke 0.79 ( ) Meta-analysis of 22 studies Diabetes 0.92 ( ) Relative Risk (95% CI) 013/sweden becomes firstwestern nation to reject low fatdiet dogma in favor of low carbhigh fat nutrition/ Adapted from Elwood et al., 2008 Some Saturated Fatty Acids Found in Dairy Fat Reduce CVD Risk Cholesterol and Diet Mega analysis Some Saturated Fatty Acids Found in Dairy Fat Reduce CVD Risk Cholesterol and Diet Mega analysis Micha and Mozzafarian 2010, from Mensik (2003) and Mozzafarian and Clark (2009) *P < 0.05 Micha and Mozzafarian 2010; from Mensik (2003) and Mozzafarian and Clark (2009) *P < 0.05

14 Metabolic Syndrome Cross-sectional case control (n=16) and prospective cohort studies (n=7) Our findings suggest an inverse doseresponse relationship between dairy consumption and risk of metabolic syndrome Chen et al., 2015 Study Year Sex OR/RR (95%CI) Relative risk Dairy, serving/day Chen et al., 2015