Should We Tell People to Eat Fish?

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Should We Tell People to Eat Fish?

• Joyce A. Nettleton
• Science Communications Consultant
• Editor, PUFA Newsletter
• Denver, CO
• Rutgers Cooperative Extension
• June 8, 2004

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Should We Eat Fish?
Neurodevelopment
Heart Health
Mental Health
Immune Inflammatory Function
Gene Expression
Respiratory Function
Visual Function
Clinical Conditions
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Should We Eat Fish?

• When Biotechnology Breakthroughs Focus on
  Omega-3s . . .
• Transgenic canola produced 16 to 23 stearidonic
  acid (184n-3), Calgene,1999
• Transgenic mice converted omega-6 to omega-3
  PUFAs, Feb. 2004
• Transgenic Arabidopsis thaliana synthesized EPA
  and AA, May 2004

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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Should We Eat Fish?

• When the American Heart Association . . .
• Recommends that all adults eat fish
  (particularly fatty fish) at least two times a
  week . . .

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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 . . .

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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Should We Eat Fish?
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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

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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

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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

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Should We Eat Fish?

• But we have forgotten . . .

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Should We Eat Fish?

• Its the dose that makes the poison
• - Paracelsus
  1493-1541

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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 t50 50-70 days in adults,
  90 in children

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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

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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

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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

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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 0.48 - 2.7 pcg/kg/bw/day

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Should We Eat Fish?

• Farmed vs.Wild
• Different species Atlantic vs five Pacific
  species
• Higher fat content 10.9 vs 4.4-7.5 g/100g
• Sockeye king 10.9-13.3 g/100g
• More EPADHA 2.4 vs 1.0-1.7
• Both low in Hg and other contaminants
• Issues pertain to environmental not safety
• Added castaxanthin or astaxanthin are same as
  naturally occurring colorants

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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Should We Eat Fish?

• Cardiovascular Benefits
• Reduce the chance of sudden death by making
  arrhythmia less likely
• gt 300,000 deaths/yr
  
  are sudden deaths
• gt 80 of these are sudden
  cardiac deaths preventable ones

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Should We Eat Fish?

• GISSI Study 11,324 MI survivors who consumed
  850-880 mg EPADHA/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 EPADHA consumption,
  mostly in patients with CVD or type 2 diabetes

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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

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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

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Should We Eat Fish?

• Reduce the risk of stroke
• ? Risk of ischemic stroke by 45 in men 40-75 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 (gt10 g/day) of n-3 LC-PUFAs
  associated with ? risk of hemorrhagic stroke

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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

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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

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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)

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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

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Should We Eat Fish?

• Reduce risk of blood clotting
• ? Risk of platelet aggregation
• May ? some clotting factors such as fibrinogen
• May ? clot breakdown

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Should We Eat Fish?

• Modestly reduce blood pressure
• Consumption of fish oil or EPADHA is associated
  with modest reductions in systolic and diastolic
  blood pressure, especially in those with elevated
  pressure

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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 ?

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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

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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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

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Should We Eat Fish?

• Other Health Effects
• May ? risk of certain mental disorders, e.g.
  depression, bipolar disorder, Alzheimers
• May ? symptoms of cystic fibrosis
• May improve graft patency in dialysis
• May improve symptoms of atopy

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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Should We Eat Fish?

• Not All Omega-3s Are Equal
• Fish have long-chain omega-3s, EPA DHA
• Plants have alpha-linolenic acid, 183n-3, which
  is converted to long-chain forms inefficiently
  (lt1)
• 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

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Should We Eat Fish?

• Should We Tell People to Eat Fish?

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Should We Eat Fish?
Current Treatment for CVD
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Should We Eat Fish?
Inuit Approach . . .