The health benefits of shellfish: What should we be promoting? Professor Bruce Griffin Nutrition Division Faculty of Health & Medical Sciences

The health benefits of shellfish: What should we be promoting? Professor Bruce Griffin Nutrition Division Faculty of Health & Medical Sciences

What should we be promoting? Define health benefits in terms of risk reduction and disease prevention

Coronary Heart Disease Thrombus Plaque Plaque rupture Coronary atherosclerosis Coronary thrombosis

Age-adjusted 6-year death rate per 1000 men Relationship between CHD death and blood cholesterol Total deaths CHD deaths Blood cholesterol (mmol/l)

Obesity, metabolic syndrome & diabetes: Major sources of cardio-metabolic risk Frequency in UK by 2020 Obesity Type 2 diabetes 25-30% >6%

Metabolic Syndrome: Major source of increased cardio-metabolic risk Pro-inflammatory & Pro-coaguable states Vascular dysfunction Hypertension Obesity (central adiposity) Insulin Resistance (Hyperinsulinaemia) Glucose intolerance Abnormal blood lipids TG HDL Intolerance to dietary fat Abnormal small, dense LDL

What are the Risks and Benefits of Diet?

What are the Risks and Benefits of Diet? Risks and Benefits Associated with Shellfish? Quantity - Passive over consumption of food energy (fat and carbohydrate) Quality - Types of fat and carbohydrate Fatty acids (as triglyceride) Dietary cholesterol Saturates Monounsaturates Polyunsaturates Omega-6 Omega-3

Cholesterol Risks?

Blood Cholesterol Dietary Cholesterol? Coronary Heart Disease Low Density Lipoprotein (LDL)

Change in Blood Cholesterol (mmol/l) Effect of dietary cholesterol on blood cholesterol: Depends on baseline intake of dietary cholesterol and how much you add to your diet Baseline intake of cholesterol (mg/day) Δ< 0.2mM ~1 egg or ~150g prawns / day Added Dietary Cholesterol (mg/day)

Calculated Effects of Dietary Cholesterol versus Saturated Fat on Blood Cholesterol Change in dietary cholesterol 100 mg/day (~half an egg yolk) Change in saturated fat 1% total energy (~2-3g) Change in blood cholesterol ~0.06 mmol/l (~2mg/dl) ~1-3% change in CHD risk

Food Example ~10g saturated fat Blood cholesterol-raising potential Saturated Fat vs Dietary Cholesterol ~5 : 1 ~80mg cholesterol

Energy, fat, saturated fat and cholesterol content of selected foods / 100g McChance & Widdowson, 2007 Energy Fat Saturated fat Cholesterol (Kj / Kcal) (g) (g) (mg) Egg (boiled) 612 / 147 10.8 3.1 391 Prawns (boiled) 418 / 99 0.9 0.2 280 Crab (boiled) 535 / 128 5.5 0.7 72 Mussels (boiled) 440 / 104 2.7 0.5 58 Oysters Burger (raw) 1206 275 / / 65 291 24.7 1.3 10.7 0.2 57 76 Pork sausage 1282 / 309 25.0 9.2 60 (raw, 65-70% meat) Energy Fat Saturated fat Cholesterol (Kj / Kcal) (g) (g) (mg) Egg (boiled) 612 / 147 10.8 3.1 391 Prawns (boiled) 418 / 99 0.9 0.2 280 Crab (boiled) 535 / 128 5.5 0.7 72 Mussels (boiled) 440 / 104 2.7 0.5 58 Burger 1206 / 291 24.7 10.7 76 Pork sausage 1282 / 309 25.0 9.2 60 Sausage roll 1596 / 383 27.6 11.2 N (with (raw, puff 65-70% pastry) meat) Sausage roll 1596 / 383 27.6 11.2 N (with puff pastry)

Dietary Intervention Study with Cold Water Prawns 225g/day for 4 weeks

Composition (/100g) of Prawns and Crabsticks Energy Protein Fat Cholesterol EPA+DHA (Kcals) (g) (g) (mg) (mg) Cold water prawns (in shell) 100 21.2 1.73 165 547 Shelled, 62 13.9 0.74 131 267 & cooked Crab sticks 115 7.80 1.60 trace trace 225g prawns deliver between 295-371mg cholesterol & 0.6-1.2g long chain omega-3

Prawn Study Design Randomisation Randomly Study Controlled design Cross-over Wash-out + Habitual crab sticks diet 4wks + crab sticks Habitual diet Habitual diet Run-in 1wk 4 weeks 4 weeks + prawns + prawns Diet diary D 1 D 2 D 3 Blood S 1 S 2 S 3 S 4 S 5 Samples

Total plasma cum cholesterol Chol (mmol/l) Prawns: No effect on Total Plasma Cholesterol 7 6 5.1 ± 0.8 5.1 ± 0.8 5 4 3 Pre-prawn 1 Post-prawn 2 Pre-control 3 Post-control 4 code

Benefits? Long chain omega-3 fatty acids

Polyunsaturated Fatty Acids Principal Dietary Sources of Long Chain Omega-3 Fatty Acids

Regular fish-consumption linked to reduced risk of CHD 36g fish / day (2.2 servings / week) Delivered 0.9g EPA/DHA (as fresh salmon) ~20% reduction in relative risk CHD death ~10% reduction in relative risk total CHD Whelton SP et al (2004) Am J Cardiol 93, 1119-1123

Diet And Reinfarction Trial (DART) Effects of changes in fat, fish and fibre intake on death and myocardial re-infarction: 2033 post-mi men randomised to receive either: Fibre advice 18g cereal fibre daily Fatty fish advice 2 portions (200-330g) of oily fish per week + MaxEPA (~20%) Fat intake advice 30% energy P:S ratio = 1.0 Burr et al (1989) Lancet: 2; 756-761

Results of DART Fibre advice 18g cereal fibre daily Higher mortality (NS) Fatty fish advice 2 portions (200-330g) of oily fish per week 29% & 32% reductions in 2 year all-cause mortality and CHD mortality respectively Fat intake advice 30% energy P:S ratio = 1.0 No effect Attributable to reduction in sudden cardiac deaths

Dietary Supplementation with Omega-3 PUFA Post-MI GISSI - Prevention Trial Study groups Patients 3mth post-mi n-3 PUFA (0.9mg EPA:DHA (2:1)/d) vitamin E (300mg -tocopherol/d) n-3 PUFA + vitamin E Control intervention 3.5 years Omega-3 PUFA Control Relative risk* (n=2836) (n=2828) (95% CI) Combined endpoints Death, non-fatal MI, non-fatal stroke 356 (12.3%) 414 (14.6%) 0.85 (0.74-0.98) Cardiovascular death, non-fatal MI, non-fatal stroke 262 (9.2%) 322 (11.4%) 0.80 (0.68-0.95) * 4-way ANOVA GISSI-Prevenzione Investigators (1999) Lancet 354, 447-455

Recommendations for intake of long chain omega-3 fatty acids (AHA) Population People without documented coronary heart disease Recommendation Target intake 0.4g/day: Eat a variety of (preferably fatty) fish at least twice a week Patients with documented coronary heart disease Target intake 0.9g/day: From fatty fish, but EPA+DHA supplements could be considered in consultation with physician Patients who need to lower their triglycerides Target intake 2-4g/day EPA + DHA: provided as supplements under a physician s care

Manifestations of Coronary Heart Disease Atherosclerosis Thrombosis Arrhythmias Anti-inflammatory Anti-atherosclerotic Stabilise plaque Anti-thrombotic Stabilise myocardium Anti-arrhythmic Multiple Actions of Long Chain Omega-3 Fatty Acids

Fish EPA plus DHA (mg/100g eaten) 2 servings ~0.3-0.6g/d Approximate amounts of EPA & DHA in dry heat cooked fish Bays H (2006) Am J Cardiol 98, 71i-76i

Long Chain Omega-3 Fatty Acids in Shellfish EPA + DHA mg/100g Data provided by Shellfish Association of Great Britain; Isherwood et al, (2010) Cell & Mol Biol 56; 50-55

What is the Target Population for Omega-3 fatty acids? Consider mechanisms of action of LC omega-3s Decrease arrhythmia by stabilising electrical activity of heart muscle Decrease risk of thrombosis Increase vascular reactivity decrease blood pressure Decrease atherosclerotic progression Lower plasma triglycerides Reduce inflammatory response Reduce cardio-metabolic risk

Projected future recommendations for intake of long chain omega-3 fatty acids Population People People without at increased documented coronary cardio-metabolic heart disease risk (Obese, metabolic syndrome) type II diabetes Patients with documented coronary heart disease Recommendation Target intake 0.4g/day: Eat a variety of fatty fish and/or shellfish at least twice a week Target intake 0.9g/day: From fatty fish, but EPA+DHA supplements could be considered in consultation with physician Patients who need to lower their triglycerides Target intake 2-4g/day EPA + DHA: provided as supplements under a physician s care

The health benefits of shellfish: What should we be promoting? Summary The case to support a link between dietary cholesterol, in such foods as shellfish (eg. prawns), and clinically significant increases in blood cholesterol is scientifically unfounded Shellfish provide a sustainable source of dietary long chain omega-3 fatty acids, the cardio-protective effects of which may be comparable to that of oily fish

?

Thank You