Dietetic Guidelines for Dietetic Guidelines for Secondary Prevention of Secondary Prevention of Cardiovascular DiseaseCardiovascular Disease

Alison Mead Chief DietitianOn behalf of

UK Heart Health and Thoracic Dietitian’s Specialist Group of the BDA

UK HEART HEALTH GROUPUK HEART HEALTH GROUP

• UK Heart Health & Thoracic Specialist Group of British Dietetic Association– Approx 70 members

• Dietetic Guidelines: Diet in Secondary Prevention of CVD– Published August 2001– 1st update August 2004– 2nd update October 2006 In press

Previous Guideline Previous Guideline recommendationsrecommendations

1. Increased omega 3 fat intake

2. Reduction in saturated fat with total or partial replacement by unsaturated fat

3. Mediterranean dietary advice for those that have suffered an MI

Literature SearchLiterature Search

• Cochrane, DARE, MEDLINE, EMBASE to Jan 05

• Identify all Systematic Reviews of Randomised Controlled Trials for diet and secondary prevention of CVD with the following outcomes:– Further CVD (MI, angina, stroke, PVD, CABG, PTCA)– Death– CV risk factors (lipids, weight, central obesity, BP,

DM, raised homocysteine)

InclusionInclusion

• Reviews were included if:– Outcome data from RCTs could be separated

from other data– Intervention was some sort of dietary advice– At least one RCT was in people with CVD and

no heterogeneity to those without– Outcomes

• Further CVD (MI, angina, stroke, PVD, CABG, PTCA)• Death• CV risk factors (lipids, weight, central obesity, BP,

DM, raised homocysteine)

GRADING THE EVIDENCE:GRADING THE EVIDENCE:

• Evidence was graded on the quality of evidence

– Excellent = 1, evidence from RCTs or SRs

• It was also graded on importance of outcomes

– A= on morbidity or mortality

– B= on a risk factor

1A

Quality Quality AssessmentAssessment

GUIDELINES:GUIDELINES:ssummary based on evidence 1Aummary based on evidence 1A

• There are systematic reviews on the effects of the following dietary factors on cardiovascular disease or death:

Omega 3 Fats Mediterranean diet

Low or modified fat Antioxidant vitamin supps

Garlic supplements Gingko biloba

Low GI diets Homocysteine lowering therapies

Multifactorial interventions

GUIDELINES:GUIDELINES:ssummary based on evidence 1Bummary based on evidence 1B

• There are SR for dietary factors effect on cardiovascular risk factors:

– Omega 3 Fats

– Low fat/ 600kcal deficit

– Fat replacement

– Low GI diets

– Garlic supplements

– Homocysteine lowering therapies

– Multifactor interventions

Omega-3 fat and mortalityOmega-3 fat and mortality

Eating n-3 fatty acids or taking fish oil supplements (1g/d) both reduce mortality in patients that have had an MI (Bucher et al. 2002)

3 portions of oily fish/ week

or 1g/d from supplement (Docosahexanoate acid/ Eicosapentaenoic acid)

Not clear whether this is quantity of n-3 fatty acids are beneficial in CVD patients that have not suffered an MI. (Hooper et al 2004, Wang et al 2004)

Copyright ©2006 BMJ Publishing Group Ltd.

Hooper, L. et al. BMJ 2006;332:752-760

Fig 3 Effect of omega 3 fatty acids on cardiovascular events.

Omega-3 fat and mortalityOmega-3 fat and mortality

In diabetics fish oil does not worsen glycaemic control or LDL levels. (Farmer 2002)

Plant Based:Evidence for effectiveness of plant-based omega-3 fats

(eg rapeseed oil/canola flax or linseed oil) is unclear.

But, the effectiveness of the Mediterranean diet in the Lyon study, which gave out rapeseed margarine, means it is probably appropriate to suggest vegetarian sources of omega-3 fats for those who cannot take fish or fishoil.

Mediterranean diet: potentially Mediterranean diet: potentially protective post MIprotective post MI

More omega-3 fats, fruit & vegetables, less saturated fat & partial replacement by rapeseed or olive oil &

more emphasis on fresh (not ready prepared) foods

(Evidence presented in a SR, but based on only 1 RCT, so not strong)

100

80

Years5

Diet

Control

De Lorgeril et al Circulation 1999;99:779

Reduction in Saturated Reduction in Saturated FatFat

• A reduced or modified fat intake, followed for at least 2 years, results in a small reduction in risk of cardiovascular events

– Up to 2 yrs - 96 events for every 100 people

– > 2 yrs – 76 events for every 100 people

AntioxidantsAntioxidants• Epidemiological data was promising• RCTs showed no benefit• Vitamin E:

– No effect on all cause mortality (RR 0.96, CI 0.84 to 1.1) or CVD risk (RR 0.97 CI 0.8 to 1.19) Skekelle 2004

– High doses (>400IU/d) increase risk of mortality (RR 1.04 CI 1.01 to 1.07) Miller 2005

• Beta- carotene– Increase risk of death (OR 1.07 CI 1.02 to

1.11) and CVD death (OR 1.1 CI 1.03 to 1.17) Vivekananthan 2003

Ginko biloba, multi-factorialGinko biloba, multi-factorial

Gingko biloba extract appears to increase pain-free walking distance modestly, in people with intermittent claudication (Pittler 2000)

Multifactorial interventions appear to be more effective than single dietary interventions at reducing mortality and morbidity in people with CVD (Ketola 2000)

Low GI, Homocysteine, Low GI, Homocysteine, GarlicGarlic

• No evidence as to whether low GI diets effect CHD mortality or events (Kelly 2004)

• No evidence as to whether plasma homocysteine lowering therapies (folate, Vit B12, B6) affect PAD progression (Hansrani 2002)

– Two recent RCTs show no effect on events NORVIT Trial NEJM 2006, HOPE 2 NEJM 2006

• No evidence of any beneficial effect of garlic supplements in people with peripheral arterial occlusive disease (Jepson, Kleijnen & Leng 1999)

Summary evidence level 1BSummary evidence level 1BDiet and Risk FactorsDiet and Risk Factors

All dietary advice to reduce lipids etc is supplementary to cardioprotective diet.

LipidsLipidsLipid Reduction - Total Cholesterol 3-6%

• Statins more effective

Modified fat intake, including fish oils

Low GI diet (not conclusive)

Garlic (not conclusive)

Weight Loss

Stanol Esters & Plant Sterols (not yet published)

Mono (Olive, Rapeseed) Mono (Olive, Rapeseed) oror

Poly (Sunflower, Walnut, Poly (Sunflower, Walnut, Sesame)?Sesame)?

• Unclear• Reduction in Total and LDL• High doses of PUFA may reduce

HDL• Mediterranean theory

Fish Oils – high doses reduces TG but increase total and LDL

LipidsLipidsLipid Reduction - Total Cholesterol 3-6%

• Statins more effective

Modified fat intake, including fish oils

Low GI diet (not conclusive)

Garlic (not conclusive)

Weight Loss (primary care)

Stanol Esters & Plant Sterols (not published)

HypertensioHypertensionn

Independent Risk Factor

Decrease 3-5mmHg SBP reduces CHD risk by 10% and stroke by 15%

DASH Trial

Hypertension SRsHypertension SRs

• Omega 3 fats– No effect on blood pressure (Hooper 2004, Morris,

Sacks & Rosner 1993)

– Small reduction in DBP in those with intermittent claudication (caution, small poor studies)

• All other SRs are from primary prevention so not included in guidelines (potassium, calcium, salt, weight)

Dietary Factors that affect Dietary Factors that affect Hypertension in primary Hypertension in primary

preventionprevention

• Salt • Weight Reduction• Alcohol• Potassium• Calcium• Dairy Peptides (Isoleucine-Proline-Proline and

Valine-Proline-Proline)

Homocysteine, Weight Homocysteine, Weight LossLoss

Raised homocysteine levels can be reduced by supplementation with folic acid, alone or with vitamin B6 and B12

No SR to show whether this effect events

Weight Loss: Low fat & 600kcal deficit resulted in 4.2kg loss more than control

Blood Glucose, HbA1c, DM Blood Glucose, HbA1c, DM diagnosisdiagnosis

• No secondary prevention reviews

LimitationsLimitations

• Lack of trials– Alcohol

• Only SRs of RCTs

• Patients that participate

SummarySummary

• Main dietary recommendations that save lives are: saturated fats & total/partially replace with

unsaturated fats (rapeseed or olive oil)

omega-3 fat intake, the amount depends on diagnosis.

• Follow a Mediterranean diet (increase omega 3 fat, fruit and vegetables and fresh foods, reduction in saturated fat and processed foods)

• Antioxidant supplements not effective