Should We Tell People to Eat Fish? Joyce A. Nettleton Science Communications Consultant Editor, PUFA Newsletter Denver, CO Rutgers Cooperative Extension June 8, 2004 Should We Eat Fish? Heart Health Neurodevelopment Mental Health Gene Expression Immune & Inflammatory Function Respiratory Function Visual Function Clinical Conditions Should We Eat Fish? When Biotechnology Breakthroughs Focus on Omega-3s . . . п‚§ Transgenic canola produced 16% to 23% stearidonic acid (18:4n-3), Calgene,1999 п‚§ Transgenic mice converted omega-6 to omega-3 PUFAs, Feb. 2004 п‚§ Transgenic Arabidopsis thaliana synthesized EPA and AA, May 2004 Should We Eat Fish? Should We Tell People to Eat Fish? Should We Eat Fish? When the American Heart Association . . . вЂњRecommends that all adults eat fish (particularly fatty fish) at least two times a weekвЂќ . . . Should We Eat Fish? When п‚§Institute of Medicine п‚§The World Health Organization п‚§Dietary Guidelines for Americans п‚§NHLBI and NCEP п‚§Countries around the world All recommend increased fish consumption . . . Should We Eat Fish? Should We Tell People to Eat Fish? Should We Eat Fish? Should We Eat Fish? Instead of the Good News . . . п‚§ п‚§ п‚§ п‚§ п‚§ п‚§ п‚§ Mercury Policy Project PCRM EPA Anti Aquaculture Groups Environmental Working Group Authors of the Hites study, Jan/04 California Prop 65 Should We Eat Fish? Each of these groups has an agenda unrelated to health . . . п‚§ Eliminate Hg emissions п‚§ Clean up or abolish aquaculture п‚§ Increase political turf п‚§ Promote environmental agenda п‚§ Increase regulation Should We Eat Fish? No Argument About . . . п‚§ Toxicity of methylmercury and risks in fetal development п‚§ Presence of Hg and other contaminants in fish and shellfish п‚§ Some species more contaminated than others п‚§ Higher levels in larger older fish than in younger smaller fish Should We Eat Fish? But we have forgotten . . . Should We Eat Fish? вЂњItвЂ™s the dose that makes the poisonвЂќ - Paracelsus 1493-1541 Should We Eat Fish? Methylmercury п‚§ Damages fetal neurodevelopment п‚§ Concentrates up food chain with size and age of fish п‚§ Present throughout fish tissues п‚§ Some protection from damage by vitamin E and selenium п‚§ Gradually eliminated t50= 50-70 days in adults, 90 in children Should We Eat Fish? Methylmercury п‚§ Majority of Americans are at low risk of adverse health effects from methylmercury: EPA п‚§ EPA reference dose: 0.1 Ојg MeHg/kg body wt/day вЂ“ 7 Ојg/day п‚§ FDA: 1 ppm max in fish п‚§ Canada: 0.5 ppm max in fish Should We Eat Fish? To Minimize Risk п‚§ Avoid shark, swordfish, king mackerel, tilefish, some sport fish п‚§ Choose species low in Hg- salmon, trout, sardines, mackerel, herring, light tuna, troll-caught tuna, tilapia, flatfish, shellfish п‚§ Eat a variety of species п‚§ Heed consumption advisories Should We Eat Fish? Organic contaminants п‚§ PCBs вЂ“ Environmental levels п‚Ї since mid 1980s; fish levels п‚Ї п‚§ FDA limit: 2000 ppb п‚§ EPA: combined estimated risks for several substances assuming risks are additive; includes more substances than FDA Should We Eat Fish? Organic contaminants п‚§ FDA: 2000 ppb п‚§ Hites study: Wild salmon 5 ppb п‚§ Farmed salmon, 37 ppb п‚§ WHO: Toxic equivalents: 1-4 pcg/kg body wt/day п‚§ Hites study: 0.48 - 2.7 pcg/kg/bw/day Farmed vs.Wild Should We Eat Fish? пЃ™ Different species: Atlantic vs five Pacific species пЃ™ Higher fat content: 10.9 vs 4.4-7.5 g/100g пЃ™ Sockeye & king: 10.9-13.3 g/100g пЃ™ More EPA+DHA: 2.4 vs 1.0-1.7 пЃ™ Both low in Hg and other contaminants пЃ™ Issues pertain to environmental not safety пЃ™ Added castaxanthin or astaxanthin are same as naturally occurring colorants Should We Eat Fish? Should We Tell People to Eat Fish? Should We Eat Fish? Cardiovascular Benefits пЃ™ Reduce the chance of sudden death by making arrhythmia less likely > 300,000 deaths/yr are вЂњsudden deathsвЂќ > 80% of these are sudden cardiac deaths вЂ“ preventable ones Should We Eat Fish? пЃ™GISSI Study вЂ“ 11,324 MI survivors who consumed 850-880 mg EPA+DHA/day had: пЃ™ 45% п‚Ї in sudden death after 4 mo. пЃ™ 30% п‚Ї cardiovascular death пЃ™ 20% п‚Ї death from all causes after 3 mo. пЃ™Many other studies have reported п‚Ї mortality from sudden death with fish or EPA+DHA consumption, mostly in patients with CVD or type 2 diabetes Should We Eat Fish? пЃ™ Reduce the risk of total CVD mortality пЃ™ Many epidemiological studies have reported п‚Ї mortality of 20% to 40% or more in populations consuming fish regularly пЃ™ Protection often but not always dose related, with consumption of 1-2 fish meals/wk providing maximum protection Should We Eat Fish? пЃ™Reduce the risk of having a first MI пЃ™ п‚Ї Prevalence of MI in elderly Dutch who consumed fish пЃ™ п‚Ї Risk of CHD in Japanese-American men in Hawaii who smoked, but ate fish пЃ™ п‚Ї Risk of CHD in women who ate fish пЃ™ п‚Ї Risk of first MI in Swedish men & women пЃ™ Not all studies have observed п‚Ї of MI or heart disease with fish consumption Should We Eat Fish? пЃ™Reduce the risk of stroke пЃ™ п‚Ї Risk of ischemic stroke by 45% in men 40-75 yr who ate fish 1-3 x a month пЃ™ п‚Ї Risk of all stroke in middle aged women, with risk inversely related to amount consumed пЃ™ Moderate fish or n-3 LC-PUFA consumption, up to 3 g/day, does not п‚ risk of hemorrhagic stroke пЃ™ Very high intake (>10 g/day) of n-3 LC-PUFAs associated with п‚ risk of hemorrhagic stroke Should We Eat Fish? пЃ™ Reduce severity of atherosclerosis пЃ™ Recent evidence that fish oils may stabilize atherosclerotic plaques making them less likely to rupture пЃ™ Fish oil consumption for 2 yr related to п‚ artery diameter пЃ™ Modest improvement in restenosis in some but not all studies Should We Eat Fish? пЃ™Improve vascular function пЃ™Inhibit excess reactivity in cells lining the blood vessels reducing inflammatory responses пЃ™Promote vascular relaxation which improves blood flow and reduces blood pressure Should We Eat Fish? пЃ™ Reduce inflammation пЃ™ Inflammation now recognized as an important risk factor in CVD and is п‚ in CVD, type 2 diabetes, metabolic syndrome, hypertension, microalbuminuria пЃ™ n-3 LC-PUFAs п‚Ї inflammatory markers and mediators of inflammatory responses (cytokines) Should We Eat Fish? пЃ™ Improve blood lipids пЃ™ Reduce triglycerides especially in people with high levels, e.g., those with type 2 diabetes, other dyslipidemias пЃ™ Improve HDL levels, especially in people with CVD, type 2 diabetes пЃ™ Modest п‚ in LDL that occurs in some people outweighed by п‚Ї TGs and п‚ HDL and other CV benefits Should We Eat Fish? пЃ™ Reduce risk of blood clotting пЃ™ п‚Ї Risk of platelet aggregation пЃ™ May п‚Ї some clotting factors such as fibrinogen пЃ™ May п‚ clot breakdown Should We Eat Fish? пЃ™ Modestly reduce blood pressure пЃ™ Consumption of fish oil or EPA+DHA is associated with modest reductions in systolic and diastolic blood pressure, especially in those with elevated pressure Should We Eat Fish? пЃ™ Boost the effectiveness of вЂњstatinsвЂќ пЃ™ n-3 LC-PUFAs increase the effectiveness of statin drugs prescribed to lower LDL cholesterol levels пЃ™ LDL levels are further п‚Ї пЃ™ HDL levels are further п‚ Should We Eat Fish? пЃ™ Reduce the risk of type 2 diabetes пЃ™ Type 2 diabetics have п‚і3x п‚ risk of CVD пЃ™ Regular consumption of fish or n-3 LC-PUFAs reduces the risk of developing type 2 diabetes in those who are insulin resistant or at high risk пЃ™ n-3 LC-PUFAs improve blood lipids, vascular function, reduce inflammation пЃ™ n-3 LC-PUFAs п‚Ї risk of CVD in those with type 2 diabetes Should We Eat Fish? Should We Tell People to Eat Fish? Other Health Effects Should We Eat Fish? п‚§ Essential for fetal & infant neurodevelopment вЂ“ very important to consume n-3 LC-PUFAs during pregnancy & lactation п‚§ Modulate immune & inflammatory function вЂ“ rheumatoid arthritis, asthma, psoriasis, atopy п‚§ May п‚Ї risk of some cancers п‚§ May п‚Ї risk of age-related macular degeneration Should We Eat Fish? Other Health Effects п‚§ May п‚Ї risk of certain mental disorders, e.g. depression, bipolar disorder, AlzheimerвЂ™s п‚§ May п‚Ї symptoms of cystic fibrosis п‚§ May improve graft patency in dialysis п‚§ May improve symptoms of atopy Should We Eat Fish? Should We Tell People to Eat Fish? Should We Eat Fish? Not All Omega-3s Are Equal п‚§ Fish have long-chain omega-3s, EPA & DHA п‚§ Plants have alpha-linolenic acid, 18:3n-3, which is converted to long-chain forms inefficiently (<1%) п‚§ Conversion of ALA is inhibited by n-6 and n-3 PUFAs п‚§ High levels of ALA do not п‚ conversion п‚§ ALA has been associated with п‚Ї risk of CVD and п‚ risk of prostate cancer вЂ“ this issue needs to be resolved Should We Eat Fish? Should We Tell People to Eat Fish? Should We Eat Fish? Current Treatment for CVD Should We Eat Fish? Inuit Approach . . .