Dairy consumption and cardiometabolic health do the trials support the epidemiology?

Transcription

1 Dairy consumption and cardiometabolic health do the trials support the epidemiology? Karen Murphy, PhD RNutr & Georgina Crichton Food Industry Forum, 31 st August 2010

2 Dairy Australians are eating serves/d (rec. 2-3) Dairy has received an unhealthy image SFA content Taste Myths (eg. phlegm, makes me fat) Evidence to support health benefits of dairy

3 Epidemiological evidence supporting cardiometabolic health benefits of dairy

4 Systematic review Crichton, Bryan, Buckley, Murphy, (under review: Obesity Reviews) - Search of electronic databases with key search terms dairy (dairy, milk, cheese, yogurt as isolated words and in combination with food, product, intake, consumption) in combination with MetS (metabolic syndrome, insulin resistance syndrome, cardiometabolic health). - Limited to adult participants - Included all cross-sectional, prospective cohort and intervention studies that reported an association between dairy intake and MetS. - Quantitative measure of dairy intake (total or individual intake) - Overall quality scored

5 Systematic review 133 citations found after removing duplicates, screening for relevance, final number of studies to include was cross sectional (Azadbakht, Beydoun, Lawlor, Liu, Mennen, Ruidavets, Shin, Snijder, Yoo, Elwood) - 3 prospective (Lutsey, Pereira, Snijder) - Characteristics of studies - Females only, males only, health professionals, middle aged to elderly, young representative of population? - Sample sizes ranged from >10,000 - Excluded individuals with diabetes or CVD, MetS, extreme energy intakes

6 Dairy and Obesity Cross-sectional Inverse relationship between milk, yoghurt, cheese and enlarged WC 1 Total dairy, milk, yoghurt, cheese, dairy desserts high fat inversely associated with WC, low fat positively associated with BMI, WC 2 Cheese intake associated with higher BMI 2 Whole fat milk & yoghurt inversely associated with central obesity, low fat milk positively associated with central obesity 3 Cheese positively associated with BMI & WC 3 Prospective Incidence of obesity reduced in overweight individuals who consumed 35 serves dairy/wk 4 High total dairy (milk, cheese, yogurt, dairy desserts, >5.75 serves/d) associated with increased BMI, weight, WC in individuals with BMI < Azadbakht et al 2005, 2 Snijder et al 2007, 3 Beydoun et al 2008, 4 Pereira et al 2002, 5 Snijder et al 2008

7 Dairy and Blood pressure Cross-sectional Inverse relationship between milk, yoghurt, cheese and hypertension 1 Total dairy associated with lower DBP 2 Milk & dairy desserts associated with lower DBP & SBP 2 All milk inversely associated with SBP & DBP 3 Men & women: milk & cheese inversely associated with DBP 4 Incidence of hypertension reduced in overweight individuals who consumed 35 serves dairy/wk 5 Prospective Incidence of hypertension reduced in overweight individuals who consumed 35 serves dairy/wk 5 1 Azadbakht et al 2005, 2 Snijder et al 2007, 3 Beydoun et al 2008, 4 Mennen et al 2000, 5 Pereira et al 2002

8 Dairy and Lipids Cross-sectional Inverse relationship between milk, yoghurt, cheese and triglycerides 1 Men: milk & cheese inversely associated with serum lipids 2 Prospective High total dairy (milk, cheese, yogurt, dairy desserts, >5.75 serves/d) associated with decreased HDL-cholesterol in individuals with BMI < Azadbakht et al 2005, 2 Mennen et al 2000, 3 Snijder et al 2008

9 Dairy and Glucose Cross-sectional Total dairy, milk, yoghurt, cheese, dairy desserts associated with higher fasting glucose 1 Total dairy, milk, yoghurt, cheese, dairy desserts high fat inversely associated with fasting glucose 2 Cheese intake positively associated with fasting glucose 2 Men: milk & cheese inversely associated with fasting glucose 3 Prospective Incidence of abnormal glucose homeostasis significantly reduced in overweight individuals who consumed 35 serves dairy/wk 4 1 Snijder et al 2007, 2 Beydoun et al 2008, 3 Mennen et al 2000, 4 Pereira et al 2002

10 Cross-sectional Dairy intake inversely associated with MetS 1-4 Dairy and MetS Yoghurt inversely associated with MetS, cheese positively associated with MetS 2,5 Adults with MetS ate less low fat dairy (0.52 serves/d) and more high fat dairy (0.95 serves/d) than those with no MetS risk factors (0.73 serves/d each) 2,6 Total dairy, low fat, high fat inversely associated with MetS 3 Milk intake inversely associated with MetS 3,7 High dairy consumption inversely associated with MetS 7 No association between dairy and MetS 8-10 Prospective Dairy intake inversely associated with MetS in overweight but not normal weight adults 11 No association between dairy and MetS 10 1 Azadbakht et al 2005, 2 Ruidavets et al 2007, 3 Liu et al 2005, 4 Mennen et al 2000, 5 Beydoun et Al 2008, 6 Yoo et al 2004, 7 Elwood et al 2007, 8 Snijder et al 2007, 9 Shin et al 2009, 10 Snijder et al 2008, 11 Pereira et al 2002

11 Evidence from intervention trials supporting CV health benefits of dairy

12 Blood Pressure n=35, low fat dairy (500mL milk + 150g yoghurt) vs CHO products (600mL juice + 3 fruit biscuits), daily for 8 weeks Reduction in SBP (2.9mmHg), HDL, Apoa1 following low fat dairy consumption 1 Reduction in plasma TNFα, stnfr1 following low fat dairy consumption 2 Skim milk led to a decrease in BP in normal and hypertensive individuals 3 In the DASH study a diet rich in fruits, vegetables and low fat dairy significantly reduced blood pressure in individuals with normal and high blood pressure, more than fruits and vegetables alone 4 Placebo controlled, double blind 34 wk study, skim milk powder daily (equiv. to 1L milk) lowered BP in normo & hypertensive hypercholesterolemic subjects 5 1 van Meijl et al 2010a, van Meijl et al 2010b, 3 Buonopane G et al 1992, 4 Appel L et al 1997, 5 Sharpe et al 1994

13 Blood lipids Early intervention studies showed skim milk or yoghurt might decrease plasma TC while whole milk had neither hypo/hyper cholesterolemic effect 1 Increased milk consumption led to a more favourable LDL particle size (less small dense LDL), reduced TAG and increased HDL 2 Placebo controlled, double blind 34 wk study, skim milk powder daily (equiv. to 1L milk) reduced TC in normo & hypertensive hypercholesterolemic subjects 3 DASH study - diet rich in fruits, vegetables and low fat dairy significantly reduced TC, LDL, HDL but no effect on TAG, relative to control, but more effective in men than women 4 1 Pfeuffer & Schrezeinmeir et al 2000, 2 Sjogren et al 2004, 3 Sharpe et al 1994, 4 Appel L et al 1997

14 Insulin Resistance Dairy is a low GI food. Milk intake led to a significantly lower glycemic response compared with mixed meals 1 DASH improvement in insulin sensitivity 2 Increased milk consumption decreased fasting insulin 3 1 Schrezenmeir J et al 1989, 2 Ard J et al 2004, 3 Sjogren et al 2004

15 DIMA Trial Metabolic health benefits of dairy protein 12 month cross-over trial - 2 sites, Manitoba, Canada & Adelaide, Australia, n=100 To evaluate the effects of regular low fat dairy consumption on markers of cardiometabolic health: body composition (% body fat, body weight, BMI, WC) lipids, CRP, insulin sensitivity arterial compliance & blood pressure resting metabolic rate (fat oxidation)

16 DIMA Trial 6 months high dairy diet 3 serves low fat dairy per day 6 months low dairy diet - <1 serve dairy per day Adelaide site has finished, Manitoba due to finish early 2011 Preliminary results (Adelaide) Regular consumption of a low fat dairy diet does not increase risk factors for CVD or body weight.

17 Do the evidence support the health benefits of dairy?

18 Yes mostly, but... Cross-sectional/prospective - inverse associations between MetS, individual CV risk factors and dairy intakes. Insulin Resistance Hypertension Obesity Dyslipidemia Inflammatory markers Small number of RCT supported the epidemiological evidence... but

19 Issues with current literature Assessment of dairy intake frequently assessed using FFQ (10/13), WFR, FR variability in reporting dairy intake type (low/high fat) and quantity Different dairy foods reported, individual products, combinations, high fat / low fat dairy Serving sizes poorly defined Small studies (n), difference in duration of trials Grouped subjects in tertiles, quartiles or quintiles Differences in the way MetS is defined We need more trials, adequately powered, of longer duration, with standardised dairy serves, standardised method of assessing dairy intake to provide more conclusive data

20 Acknowledgements Dairy Team investigators & clinical research team: Prof Peter Howe A/Pr Jon Buckley Dr Alison Coates Dr Janet Bryan Dr Curtis Rempel Dr Peter Jones Dr Gary Fulcher Amanda Jager Kate Dyer Stella Pappacharissiou Keren Kneebone Alice Murray Heather Martin