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

Food Industry Forum, 31st August 2010

Karen Murphy, PhD RNutr & Georgina Crichton

Dairy

Australians are eating 1-1.5 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

Epidemiological evidence supporting cardiometabolic health benefits of dairy

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

Systematic review

133 citations found after removing duplicates, screening for relevance, final number of studies to include was 13.

- 10 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 827 - >10,000- Excluded individuals with diabetes or CVD, MetS, extreme

energy intakes

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 BMI2

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

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 & SBP2

All milk inversely associated with SBP & DBP 3

Men & women: milk & cheese inversely associated with DBP4

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

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

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, 4Pereira et al 2002

Dairy and MetS

Cross-sectional Dairy intake inversely associated with MetS 1-4

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

1Azadbakht et al 2005, 2Ruidavets et al 2007, 3Liu et al 2005, 4Mennen et al 2000, 5Beydoun et Al 2008, 6Yoo et al 2004, 7Elwood et al 2007, 8Snijder et al 2007, 9Shin et al 2009, 10Snijder et al 2008, 11 Pereira et al 2002

Evidence from intervention trials supporting CV health benefits of

dairy

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

1 Pfeuffer & Schrezeinmeir et al 2000, 2 Sjogren et al 2004, 3 Sharpe et al 1994, 4 Appel L et al 1997

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 Schrezenmeir J et al 1989, 2 Ard J et al 2004, 3Sjogren et al 2004

Insulin Resistance

Dairy is a low GI food. Milk intake led to a significantly lower glycemicresponse compared with mixed meals 1

DASH – improvement in insulin sensitivity 2

Increased milk consumption decreased fasting insulin 3

DIMA Trial

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)

‘Metabolic health benefits of dairy protein’

DIMA Trial

6 months high dairy diet – 3 serves low fat dairy per day6 months low dairy diet -

Do the evidence support the health benefits of dairy?

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

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

‘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

Acknowledgements

Slide Number 1DairyEpidemiological evidence supporting cardiometabolic health benefits of dairySystematic reviewSystematic reviewDairy and ObesityDairy and Blood pressureDairy and LipidsDairy and GlucoseDairy and MetSEvidence from intervention trials supporting CV health benefits of dairyBlood PressureBlood lipidsInsulin ResistanceDIMA TrialDIMA TrialDo the evidence support the health benefits of dairy?Yes mostly, but....Issues with current literatureAcknowledgements