Should We Tell People to

Eat Fish?Joyce A. NettletonScience Communications

ConsultantEditor, PUFA Newsletter

Denver, CO

Rutgers Cooperative ExtensionJune 8, 2004

Should We Eat Fish?

Heart Health Neurodevelopment

Mental Health

Gene Expression

Immune &Inflammatory

Function Respiratory Function

VisualFunction

ClinicalConditions

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. 2004

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?

WhenInstitute of MedicineThe World Health OrganizationDietary Guidelines for AmericansNHLBI and NCEPCountries 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 . . .

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 1493-1541

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

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: 0.48 - 2.7 pcg/kg/bw/day

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 EPA+DHA: 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

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 850-880 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 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 (>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 . . .