| Advantages of Eating Fish for Human Health |
|
Safe food
Introduction
Some 200 different types of illness have been
identified as being transmitted by food.
Humans have suffered from illnesses transmitted
by food throughout the ages. However, in the early
1980s professionals concerned with food safety in
developed countries observed what seemed to be a
significant increase in the number of disease
outbreaks linked to food. This can be named as the
“food safety paradox” (see chapter
below). Although one lacks data, it is reasonable
to expect that cases of food-borne disease in
general are at least as frequent in developing
countries, as they are in developed countries, and
probably far more frequent.
Fish, as is true of any other food, can cause
health problems. It can be contaminated at any time
from the moment of capture until it is eaten.
Contamination may occur because pathogenic
microorganisms form part of the normal flora of the
fish. In other cases, toxic substances are
introduced through cross-contamination,
recontamination or faulty handling and
processing.
In this part of the article we will look further
into what is the health hazards of eating fish, try
to give some advices on how to reduce these risks
and give some information about what is done today
with the problem.
The “food safety paradox” and
reasons for food hazards
The increase in illnesses transmitted by food in
developed countries is perplexing, given that an
increasing proportion of foods is produced under
stringent hygienic conditions. Possible reasons for
the "food safety paradox" are:
- increased urbanization;
- improved systems for recording the
incidence of illnesses transmitted by
food;
- human and industrial pollution;
- non-rational use of antibiotics;
- new emerging pathogens;
- uncontrolled recycling of organic
material;
- increased susceptibility to
contaminants;
- increased consumption of
mass-produced foods;
- the introduction of new technologies
for "minimally processed foods";
- prolonged rains, droughts and/or
increases in average temperatures, favouring
the ecologies of pathogens.
In poorer areas of developing countries,
poverty, malnutrition, illiteracy and inadequate
public facilities are likely to compound the
situation.
Food-derived illnesses can have several causes,
including specific toxic substances, pathogenic
microorganisms and parasites that can develop
and/or be conveyed by foods. Some toxic substances
(biotoxins) may develop naturally in the
environment, while others are human-generated
contaminants (chemicals). Some pathogenic
microorganisms are part of the normal flora (e.g.
of fish) and some are contaminants.
Food-borne diseases are a function of general
food habits, the frequency of fish consumption and
the type of products and species consumed.
Fish and illnesses from infectious
diseases
In recent years, Mad Cow Disease and Foot and
Mouth Disease have drawn large attention in the
media and caused a lot of people to stop eating
meat. A Norwegian survey in EU-countries indicated
that 34% of the consumers had reduced their meat
intake due to these illnesses5. Recent
research has not indicated any connection between
Mad Cow Disease and the handling or consumption of
fish.
In general fish is not an important carrier of
food borne infectious diseases. This is in favour
of fish consumption.
Poisoning from pollution and environmental
toxins
Man himself and pollution from human activity
are the main causes for this group of problems. In
this group, some of the toxins constitute the
biggest problems6.
Pesticides
Since 1940 approximately 15,000 petroleum-based
herbicides, insecticides, fungicides, and
rodenticides have been created to kill unwanted
plants and animals. These synthetic pesticides are
unlike other techniques designed to kill and
prevent the appearance of pests in important
ways:
They are poisons. While the toxicity of
synthetic pesticides varies greatly, they are all
designed to kill plants and animals, and exposure
to some pesticides results in acute health effects
in humans and "non-pest" plants and animals.
Documented acute effects on humans include:
- nausea, fatigue, skin and muscle
reactions
- respiratory problems
- kidney and liver damage
- nervous system damage
Pesticides accumulate in the food chain and are
especially found in animals on top of the chain.
Large fish and carnivorous fish are the most
exposed.
Mercury
Mercury is a naturally occurring element that is
present throughout the environment and in plants
and animals7. Human activity can release
some of that mercury, increasing the amount
available to accumulate in humans and other
animals. Human activities have increased the amount
of mercury that is currently cycling in the
atmosphere, in soils, and in lakes, streams and the
oceans. Although there have been reductions in the
release of mercury to the environment, this are not
yet reflected in the environment.
Mercury is most harmful to man in the organic
form of methylmercury which is created from the
chemical form by biological processes. Freshwater
fish from contaminated waters have been shown to
have particularly high levels of methylmercury.
Certain species of commercially available saltwater
fish, such as shark, swordfish, kingfish and
tilefish also can contain high levels of
mercury.
Once in the body, it can affect the fetal and
adult nervous systems. At high doses, mercury
exposure can cause tremors, inability to walk,
convulsions, and even death8.
Dioxin is a general term that describes a group
of hundreds of chemicals that are highly persistent
in the environment9. Dioxin is formed as
an unintentional by-product of many industrial
processes involving chlorine such as waste
incineration, chemical and pesticide manufacturing
and pulp and paper bleaching. Dioxin is soluble in
oil and accumulate in fat tissue in live organisms
exposed to dioxin.
An American survey shows that the average daily
intake in America is 119 pg. Out of this, 7.8 pg
comes from fish while 81 pg comes from meat and
24.1 pg comes from intake of dairy
products10.
Dioxin is a cancer hazard to people. Exposure to
dioxin can also cause severe reproductive and
developmental problems.
Overall, the best strategy for lowering the risk
of dioxins while maintaining the benefits of a good
diet is to follow the recommendations in Americas
Federal Dietary Guidelines11 to choose
fish, lean meat, poultry, and low or fat free
(skim) dairy products and to increase consumption
of fruits, vegetables and grain products. Lean meat
includes meats that are naturally lower in fat, and
meat where visible fat has been trimmed. For fish
and poultry you can reduce fat by removing the
skin.
Marine biotoxins - Algae poisoning
Algae is seen everywhere because it creates the
base of both marine and freshwater food
webs12. There are three specific classes
of unicellular algae that produce the toxins which
may cause many human health problems.
Dinoflagellates, diatoms, and cyanobacteria (all
very small organisms living in water) are
responsible for producing a variety of toxins. The
known toxin producing species usually do not affect
humans directly. Illness occurs through the
consumption of seafood. Dinoflagellates, diatoms,
and cyanobacteria exist all around the world and
many do not cause any human health or similar types
of problems.
Marine biotoxins are some of the most potent
chemical compounds known. As a result, beaches and
commercial shellfish operations are closed to the
taking and sale of shellfish when they contain
toxins. Most costal nations have evolved monitoring
programs that warn the public of these dangers.
Fish and allergies
A food allergy is an immune system response to a
food that the body mistakenly believes is harmful.
Once the immune system decides that a particular
food is harmful, it creates specific antibodies to
it.
The next time the individual eats that food, the
immune system releases massive amounts of
chemicals, including histamine, in order to protect
the body. These chemicals trigger a cascade of
allergic symptoms that can affect the respiratory
system, gastrointestinal tract, skin, or
cardiovascular system.
At the present time, there is no cure for food
allergy. Avoidance is the only way to prevent an
reaction.
Allergic reactions to fish and shellfish are
commonly reported in both adults and children. It
is generally recommended that individuals who have
had an allergic reaction to one species of fish or
positive skin tests to fish avoid all fish. The
same rule applies to shellfish. If you have a fish
allergy but would like to have fish in your diet,
speak with your allergist about the possibility of
being challenged with various types of fish.
Fish-allergic individuals should be cautious
when eating away from home. They should avoid fish
and seafood restaurants because of the risk of
contamination in the food-preparation area of their
"non-fish" meal from a counter, spatula, cooking
oil, fryer, or grill exposed to fish.
|
Send page by email
Printer Friendly Version
Previous
Next
