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Current View
Introduction
P
eople are encouraged to believe that a healthy diet is one which
includes fish. The reason being that some fish contain the types of
‘good’ fat that our bodies need. There is a widespread
misconception amongst the general public and health professionals
that fish is the only source of these good fats.
There are two reasons why these ideas have become so well
established. Firstly, much has been made of the healthiness of the
Mediterranean diet, which is based on generous servings of fruits
and vegetables, cereals and olive oil and where fish is served in
preference to meat or dairy products. Mealtimes tend to be very
social and this may have profound implications for health.
Secondly, a number of studies have examined the effect of fish in
helping to prevent a second heart attack in people who have
already had one attack and these show some protection benefits.
F
ats in the Diet
There’s a lot of confusion about fat and diet, but the truth is that our
bodies can’t function without it. Eating the right
kind
of fat is,
however crucial. What we don’t need are saturated fats, found
mainly in meat, dairy and animal products, but also in many
processed foods. These are strongly linked to high blood cholesterol,
hardening of the arteries, coronary heart disease, some cancers and
other degenerative diseases. We do need unsaturated fats - especially
polyunsaturated fats.
W
ithin polyunsaturated fats are substances called essential fatty
acids, or EFAs - namely omega-6 (linoleic acid - LA) and omega-3
fats (linolenic acid - LNA). Although olive oil is not an EFA it is
another type of unsaturated fat which has some healthy properties
and it is good to include it in the diet. EFAs - particularly the
omega-3 fats - help keep the heart healthy.
F
ish is a source of EFAs, particularly omega-3 fats, but not all fish
contain them. Those that do are principally oily fish such as
herring, salmon, mackerel, sardines and fresh tuna. White fish,
such as cod, haddock and plaice, don’t and nor does tinned tuna.
However, the richest sources of omega-3 fats are not fish at all but
plants. Seed oils such as linseed (flax) and rapeseed (canola) as well
as soya oil are rich sources as are seeds and nuts themselves -
particularly walnuts (1). Green leafy vegetables are also a source (2).
Omega-3 and Heart Disease
It’s been known for a long time that people whose diet is based
largely on fish and is rich in omega-3 have low rates of heart disease.
This led researchers to investigate whether giving fish to people who
had already suffered a heart attack would prevent them from having
another attack. These are ‘secondary prevention trials’ and two of the
largest are the DART and GISSI trials, which both used fish-based
omega-3 fats. They did show a reduced risk, but much less publicised
was the LYON trial, which used plant oils as a source of omega-3
fats. The results of this study showed that plant oils reduced the risk
of a secondary heart attack by at least twice that of fish oils!
D
ART T
rial
It found that males who had been advised to eat as much as 400g
of oily fish per week showed a reduction of almost 30 per cent in
mortality (death) over two years. Although there were fewer fatal
heart attacks, the total number of heart attacks wasn’t reduced. It
is thought that fish oils help to normalise heartbeat rhythms and
prevent blood from becoming too sticky and ‘clumping’ (3).
Despite this apparent reduction in risk, a follow-up study 10 years
later found there were no long-term survival benefits (4).
GIS
SI
T
rial
This trial looked at people on a Mediterranean diet who had had a
heart attack and survived it. Fish oil supplements equivalent to a
whopping 100g of oily fish per day were given and showed a 20
per cent reduction in mortality (5).
LY
ON
T
rial
This was another secondary prevention trial, but instead of fish or fish
oils, plant-derived omega-3 fatty acids were used. Amazingly, a 70 per
cent reduction in mortality was achieved - more than double that of
the fish trials! There was also a significant reduction in coronary
‘events’ and these protective effects were found to start quickly (6).
F
our years on, patients were still following the diet and their hearts
were still being protected (7). Subsequent studies have confirmed the
power of plant omega-3 fatty acids in protecting the heart (8,9).
Plant Oils Better than Fish Oils
Comparing the three main trials shows that:
plant oils are far more effective than fish oils in reducing the
chance of cardiac death in high-risk patients;
plant oils reduce the risk of dying from secondary heart attack
by more than double that of fish oils;
plant oils reduce the number of painful, non-fatal heart attacks;
•t
here are long-term survival benefits from consuming plant oils.
No Gain for Low-Risk
The trials we’ve written about all looked at people who were at
high risk of a heart attack. Because people are termed ‘low-risk’, it
doesn’t mean they will never have an attack, it simply means they
are further down the risk scale. They are those who eat low levels
of saturated fat and therefore can include vegetarians and vegans
(10,11). When researchers looked at low-risk groups they found
that eating fish had no effect on reducing their chances of dying
from a heart attack (12).
T
oxins in Fish
Human beings have been so successful at spreading pollution that
environmental contamination is widespread and all oceans now contain
toxic chemicals. Persistent organic pollutants (POPs) are now part of
most food chains and they become more concentrated the higher up
the chain you go. Mercury, organophosphates, PCBs, dioxins, and
radioactive pollution in some fish, are all highly toxic to life.
F
atty foods have a tendency to ‘soak’ up toxins and so oily fish are
particularly prone to absorbing them - the toxins are actually stored
Fish is seemingly promoted as the new penicillin. VVF uncovers the science to show that it is plant oils
and a plant based diet, not fish oils, that are the real way forward for lifelong health.
Fishing for Facts
Why public health strategy should promote
plant oils in preference to fish oils
by Laura Scott (MSc Nutrition)
VVF Snr Nutritionist
Charity number: 1037486
VVF
,
T
op Suite, 8 Y
ork Court, W
ilder Street, Bristol BS2
8QH. Tel: 0117
970 5190. Email: info@vegetarian.org.uk W
eb: www.vegetarian.org.uk
in the fatty part of the fish. By eating smaller fish, oily fish take on
their toxic load and become ever more toxic themselves! POPs are
implicated in heart disease, infertility and can harm developing
foetuses. Responding to a Food Standards Agency 2002 survey, the
Consumers’ Association warned that high levels of dioxins and PCBs
in fish and fish oil supplements could “put millions at risk” (13).
Mercury in Fish
Humans should avoid mercury in their diet as it acts like a poison,
affecting their kidneys, heart and central nervous system (CNS).
Exposure to mercury is a particular risk for unborn children where
the main organs, especially the CNS, are still developing.
Ac
cording to a government agency, fish eating is responsible for
the majority of mercury in people’s diets (14). Following a Food
Standards Agency survey of mercury levels in fish, official advice is
now for pregnant and breastfeeding women to limit how much
tuna they eat and for them and children under 16 not to eat shark,
swordfish or marlin at all. (15)
Other studies have found that over 60 per cent of bluefin tuna
caught in the Mediterranean exceed EC ‘safety’ figures.
R
esearchers have calculated that some of those people who eat
high levels of these oily fish will far exceed the World Health
Organisation’s (WHO) ‘safety’ levels (16, 17). A 2000
government study failed to detect any mercury in vegetarian
diets and concluded, “it is reasonable to assume that because
participants in this study did not eat fish, their dietary
exposures to mercury will be substantially less than those of
the general population” (18).
Protect and Survive
One way mercury harms the body is by acting as a potent free
radical. Free radicals are unstable molecules that damage body cells
and the body’s main defence against them are antioxidants - beta-
carotene (converted to vitamin A), and vitamins C and E. Plant
foods are rich in these antioxidants and plant oils are particularly
rich in vitamin E, which stops EFAs from deteriorating or going
off. Only plant oils, not fish oils, contain protective vitamin E.
How Much Fish?
The FSA seem as muddled as everyone else about how much fish
people should eat each week. Some of its publications say two
servings and others say at least two servings. But, in any case, surveys
show the vast majority of people are unaware of the official advice
and most people are confused by what is meant by oily fish (13).
P
ublic Health F
ailure
The average UK consumption of oily fish is 53g per person per week
(19). This meagre quantity represents only about a third of a single
portion and is a tiny amount compared to the 400g weekly intake of
oily fish which have been used to produce heart benefits in research
studies. This shows that all the attempts to get the British public to
eat fish is a spectacular failure.
Alternatives to Fish Oils
Seeds, nuts, beans and their oils are the richest-known sources of
the ‘good’ fats. Green leafy vegetables also contain these essential
fats. Walnuts, linseed (flaxseed) and rapeseed oil (canola) are all
exceptionally rich in omega-3 fats.
The best way to buy and store nuts, seeds and their oils is in very
small quantities and to keep them in the fridge. This helps to
ensure that they are as fresh as possible. These oils are not suitable
for heating as it destroys the beneficial EFAs. Most healthfood
shops and supermarkets sell packets of nuts and seeds and blended
plant oils - usually marketed as oils rich in omega-3 and omega-6
fats. They contain information on how much oil to use each day.
W
ith whole seeds and nuts, a handful each day is normally
sufficient. Olive oil can be used for cooking.
Fishless Foods
F
ish-like substitutes are available thanks to food technologists who
have produced imitation fish fingers, scampi, tuna and salmon paté
that actually taste of fish. They are available in most healthfood shops.
Intelligent Public
Health Promotion
A
dding fish to the diet will not bring about long-term good health.
Plant-based vegetarian and vegan diets are the best choice for
optimum health.
Summary
Plant oils are a far healthier source of the essential fats we need.
Plant oils halve the risk of heart disease compared with fish oils.
•F
ish is a spectacularly unpopular food in the UK.
•F
ish is likely to be contaminated with harmful chemicals.
Plant oils are far less likely to turn rancid than fish oils.
Plant oils as nuts and seeds are the ultimate fast food.
Plant-based diets offer protection against many diseases.
Our hearts don’t need fish, our brains don’t need fish and our health
is far better served by plant oils and a well-balanced plant-based diet.
References
1 Buttriss J, 1999. n-3 Fatty Acids And Health. p.1. (BNF)
2 Pereira C et al, 2001. The Alpha-Linolenic Acid Content of Green Vegetables
Commonly Available in Australia. Int. J. Vitam. Nutr. Res.;71(4):223-228.
3 Burr ML et al, 1989. Effects of Changes in Fat, Fish and Fibre Intakes on
Death and Myocardial Reinfarction: Diet And Reinfarction Trial (DART). The
Lancet;8666:757-761.
4 Ness AR et al, 2002. The Long-Term Effect of Dietary Advice in Men with
Coronary Disease: Follow-Up of the Diet and Reinfarction Trial (DART). Europ.
J. Clin. Nutr.;56:512-518.
5 GISSI-Prevenzione Investigators, 1999. Dietary Supplementation with N-3
P
olyunsaturated Fatty Acids and Vitamin E After Myocardial Infarction: Results
of the GISSI-Prevenzione Trial. The Lancet;354:447-455.
6 De Lorgeril M et al, 1994. Mediterranean Alpha-Linolenic Acid-Rich Diet in
Secondary Prevention of Coronary Heart Disease. The Lancet;343:1454-1459
7 De Lorgeril M et al, 1999. Mediterranean Diet, Traditional Risk Factors and
the Rate of cardiovascular Complications After Myocardial Infarction.
Circulation;99:779-785.
8 Singh RB et al, 1997. Randomised, Double-Blind, Placebo-Controlled Trial of
F
ish Oil and Mustard Oil in Patients with Suspected Acute Myocardial Infarction:
The Indian Experiment of Infarct Survival-4. Cardiovas. Drugs and
Therapy;11:485-491.
9 Singh RB et al, 2002. Effect of an Indo-Mediterranean Diet on Progression of
Coronary Artery Disease in High Risk Patients (Indo-Mediterranean Diet Heart
Study): A Randomised Single-Blind Trial. The Lancet;360:1455-1461.
10 Key TJ et al, 1999. Health Benefits of a Vegetarian Diet. Proc. Nutr Soc.;58:271-275.
11 ADA Reports. Position of the American Dietetic Association and Dietitians of
Canada: Vegetarian Diets. 2003. JADA;103(16):748-765.
12 Marckmann P & Gronbaek M, 1999. Fish Consumption and Coronary Heart
Disease Mortality. A Systematic Review of Prospective Cohort Studies. Europ. J.
Clin. Nutr.;53:585-590.
13 Consumers’ Association, ‘Fish – what’s the catch’, Which?, p.7-9, October 2002.
14 COT Statement (2002/04) in December 2002 concerning a FSA survey on the
levels of mercury in fish and shellfish.
15 FSA statement ref: 40/2003, Mercury in imported fish and shellfish, UK
farmed fish and their products, July 2003.
16 Storelli MM et al, 2002. Total and Methylmercury Residues in Tuna-Fish
from the Mediterranean Sea. Food Add. And Contam.;19(8):715-720.
17 Storelli MM et al, 2003. Total Mercury and Methylmercury Content in Edible
fish from the Mediterranean Sea. J. of Food Protection;66(2):300-303.
18 MAFF, 2000, Duplicate Diet Study of Vegetarians.
19 Food Standards Agency, 2002, The National Diet and Nutrition Survey: adults
aged 19 to 64 years, HMSO.
This is one in a series of VVF
factsheets. VVF also publish
a Fishing for F
acts report and a
fish information leaflet. For details contact:
VVF
,
T
op Suite, 8 Y
ork Court, W
ilder Street, Bristol BS2
8QH. Tel: 0117
970 5190. Email: info@vegetarian.org.uk W
eb: www.vegetarian.org.uk