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...  Transgenic canola produced 16% to 23% stearidonic acid (18:4n-3), Calgene,1999  Transgenic mice converted omega-6 to omega-3 PUFAs, Feb  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... “Recommends that all adults eat fish (particularly fatty fish) at least two times a week”...

Should We Eat Fish? When  Institute of Medicine  The World Health Organization  Dietary Guidelines for Americans  NHLBI and NCEP  Countries around the world All recommend increased fish consumption...

Should We Eat Fish? Should We Tell People to Eat Fish?

Should We Eat Fish?

Instead of the Good News...  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...  Eliminate Hg emissions  Clean up or abolish aquaculture  Increase political turf  Promote environmental agenda  Increase regulation

Should We Eat Fish? No Argument About...  Toxicity of methylmercury and risks in fetal development  Presence of Hg and other contaminants in fish and shellfish  Some species more contaminated than others  Higher levels in larger older fish than in younger smaller fish

Should We Eat Fish? But we have forgotten...

Should We Eat Fish? “It’s the dose that makes the poison” - Paracelsus

Should We Eat Fish? Methylmercury  Damages fetal neurodevelopment  Concentrates up food chain with size and age of fish  Present throughout fish tissues  Some protection from damage by vitamin E and selenium  Gradually eliminated t 50 = days in adults, 90 in children

Should We Eat Fish? Methylmercury  Majority of Americans are at low risk of adverse health effects from methylmercury: EPA  EPA reference dose: 0.1 μg MeHg/kg body wt/day – 7 μg/day  FDA: 1 ppm max in fish  Canada: 0.5 ppm max in fish

Should We Eat Fish? To Minimize Risk  Avoid shark, swordfish, king mackerel, tilefish, some sport fish  Choose species low in Hg- salmon, trout, sardines, mackerel, herring, light tuna, troll-caught tuna, tilapia, flatfish, shellfish  Eat a variety of species  Heed consumption advisories

Should We Eat Fish? Organic contaminants  PCBs – Environmental levels  since mid 1980s; fish levels   FDA limit: 2000 ppb  EPA: combined estimated risks for several substances assuming risks are additive; includes more substances than FDA

Should We Eat Fish? Organic contaminants  FDA: 2000 ppb  Hites study: Wild salmon 5 ppb  Farmed salmon, 37 ppb  WHO: Toxic equivalents: 1-4 pcg/kg body wt/day  Hites study: pcg/kg/bw/day

Should We Eat Fish? Farmed vs.Wild  Different species: Atlantic vs five Pacific species  Higher fat content: 10.9 vs g/100g  Sockeye & king: g/100g  More EPA+DHA: 2.4 vs  Both low in Hg and other contaminants  Issues pertain to environmental not safety  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  Reduce the chance of sudden death by making arrhythmia less likely > 300,000 deaths/yr are “sudden deaths” > 80% of these are sudden cardiac deaths – preventable ones

Should We Eat Fish?  GISSI Study – 11,324 MI survivors who consumed mg EPA+DHA/day had:  45%  in sudden death after 4 mo.  30%  cardiovascular death  20%  death from all causes after 3 mo.  Many other studies have reported  mortality from sudden death with fish or EPA+DHA consumption, mostly in patients with CVD or type 2 diabetes

Should We Eat Fish?  Reduce the risk of total CVD mortality  Many epidemiological studies have reported  mortality of 20% to 40% or more in populations consuming fish regularly  Protection often but not always dose related, with consumption of 1-2 fish meals/wk providing maximum protection

Should We Eat Fish?  Reduce the risk of having a first MI   Prevalence of MI in elderly Dutch who consumed fish   Risk of CHD in Japanese-American men in Hawaii who smoked, but ate fish   Risk of CHD in women who ate fish   Risk of first MI in Swedish men & women  Not all studies have observed  of MI or heart disease with fish consumption

Should We Eat Fish?  Reduce the risk of stroke   Risk of ischemic stroke by 45% in men yr who ate fish 1-3 x a month   Risk of all stroke in middle aged women, with risk inversely related to amount consumed  Moderate fish or n-3 LC-PUFA consumption, up to 3 g/day, does not  risk of hemorrhagic stroke  Very high intake (>10 g/day) of n-3 LC-PUFAs associated with  risk of hemorrhagic stroke

Should We Eat Fish?  Reduce severity of atherosclerosis  Recent evidence that fish oils may stabilize atherosclerotic plaques making them less likely to rupture  Fish oil consumption for 2 yr related to  artery diameter  Modest improvement in restenosis in some but not all studies

Should We Eat Fish?  Improve vascular function  Inhibit excess reactivity in cells lining the blood vessels reducing inflammatory responses  Promote vascular relaxation which improves blood flow and reduces blood pressure

Should We Eat Fish?  Reduce inflammation  Inflammation now recognized as an important risk factor in CVD and is  in CVD, type 2 diabetes, metabolic syndrome, hypertension, microalbuminuria  n-3 LC-PUFAs  inflammatory markers and mediators of inflammatory responses (cytokines)

Should We Eat Fish?  Improve blood lipids  Reduce triglycerides especially in people with high levels, e.g., those with type 2 diabetes, other dyslipidemias  Improve HDL levels, especially in people with CVD, type 2 diabetes  Modest  in LDL that occurs in some people outweighed by  TGs and  HDL and other CV benefits

Should We Eat Fish?  Reduce risk of blood clotting   Risk of platelet aggregation  May  some clotting factors such as fibrinogen  May  clot breakdown

Should We Eat Fish?  Modestly reduce blood pressure  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?  Boost the effectiveness of “statins”  n-3 LC-PUFAs increase the effectiveness of statin drugs prescribed to lower LDL cholesterol levels  LDL levels are further   HDL levels are further 

Should We Eat Fish?  Reduce the risk of type 2 diabetes  Type 2 diabetics have  3x  risk of CVD  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  n-3 LC-PUFAs improve blood lipids, vascular function, reduce inflammation  n-3 LC-PUFAs  risk of CVD in those with type 2 diabetes

Should We Eat Fish? Should We Tell People to Eat Fish?

Should We Eat Fish? Other Health Effects  Essential for fetal & infant neuro- development – very important to consume n-3 LC-PUFAs during pregnancy & lactation  Modulate immune & inflammatory function – rheumatoid arthritis, asthma, psoriasis, atopy  May  risk of some cancers  May  risk of age-related macular degeneration

Should We Eat Fish? Other Health Effects  May  risk of certain mental disorders, e.g. depression, bipolar disorder, Alzheimer’s  May  symptoms of cystic fibrosis  May improve graft patency in dialysis  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  Fish have long-chain omega-3s, EPA & DHA  Plants have alpha-linolenic acid, 18:3n-3, which is converted to long-chain forms inefficiently (<1%)  Conversion of ALA is inhibited by n-6 and n-3 PUFAs  High levels of ALA do not  conversion  ALA has been associated with  risk of CVD and  risk of prostate cancer – 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...