Raw fish - Risks and benefits of raw fish
Raw fish represents a "slice" (forgive the pun) of traditional food culture, identifiable in every region or coastal-maritime locality of the globe.
Until a few decades ago, in Italy the term "raw fish" meant above all recipes based on marinated products, such as anchovies (or anchovies) with flagship or citrus fruits, oysters and mussels with lemon etc. and sea urchin eggs.
On the other hand, today the consumption of raw fish is not limited to these few preparations, quite the opposite! The carpaccio fish: tuna, swordfish, amberjack, red snapper, sea bream ... but also shellfish: cape sante, cuttlefish ... and crustaceans: lobster, lobster, whole prawns, large-sized prawns. Not least, even if a little more sophisticated, are the tartare, which provide (more or less) the use of the same fish species mentioned among the carpaccio.
We also remind you that, in addition to "commercial" catering preparations, there are less common but still noteworthy habits that involve the consumption of animals taken and eaten directly in the marine environment. Among these, the most common are undoubtedly: bivalve molluscs. (mussels, clams, oysters and cockles), gastropod molluscs (limpets, sea ears), sea urchin eggs, and a few other creatures (crustaceans and fish).
Risks to health
By frequently feeding on raw fish (where by fish we mean ALL fishery products), the chances of contracting certain diseases are increased; it is an extremely vast subject that includes notions of veterinary medicine, microbiology, marine biology, food hygiene, etc., however, we will try to propose a general "simple" but sufficiently exhaustive framework.
Among the diseases related to the consumption of raw fish, the most important are:
- Parasitosis, due to the intake of food contaminated by pathogenic organisms (protozoa, larvae, amoeba, etc.)
- Infections, due to the intake of food contaminated by pathogenic microorganisms (bacteria and viruses)
- Poisoning, due to the intake of food contaminated ONLY by bacterial toxins or algae
- Toxinfections, due to the intake of food contaminated by BOTH pathogenic bacteria and their respective toxins
The tendency of bivalve molluscs (which feed by filtering the water) to retain some pathogenic organisms and microorganisms, which, if not carefully neutralized through cooking, can cause serious and even fatal diseases. The best known are undoubtedly:
- Viral hepatitis: systemic-hepatic disease determined ESPECIALLY by the virus HAV
- Foodborne infection by Salmonella Typhi and Paratiphi: responsible for typhoid fever and salmonellosis.
- Cholera toxinfection: a tendentially epidemic pathology originating from Vibrio Colerae; once frequently widespread in southern Italy
- Fecal coliform toxinfection: determined by the "Escherichia Coli
- Toxic infection with Vibrio Parahaemoliticus, which is of particular interest to Japan
However, discussing the hygiene of the consumption of raw fish inevitably ends up talking above all about PARASITOSIS. In this regard, even in Italy - where, in addition to the very recent sushi, it is now traditional to consume marinades, carpaccio and fish tartare (swordfish, tuna, amberjack, bonito, anchovies, etc.) - the diagnoses of intestinal parasitosis are beginning to increase from ANISAKIS (anisakiadee). Especially in Liguria, the consumption of "lemon marinated anchovies" caused a significant increase in the onset of anisakiasis.
In order to prevent the spread of this pathogen, a series of laws was enacted in 1997 in the field of the food industry and collective catering. According to this regulation, the catering sale and administration of raw fish is explicitly PROHIBITED IF NOT previously thermally knocked down at temperatures of -20 ° C for at least 24 hours. It is known that anisakis is an organism present in larval form only in fish (especially in blue fish), in which it occupies exclusively the internal portion of the intestinal lumen. On the contrary, in mammals (marine and otherwise) the larvae progress and develop significantly modifying their metabolism and their pathogenicity.
At this point a question arises: if the anisakis is present ONLY in the bowels of the fish ... of which obviously the final consumer does not feed ... how is it possible to contract anisakiasis?
The answer is very simple: although the anisakis is not able to pierce the intestine of fish still alive, from the moment of their death (and from the relative collapse of the immune barriers) the parasite acquires the ability to migrate inside the tissues. muscles of the animal. It follows that, for personal consumption, having the certainty of gutting the fish immediately after capture, it is possible to consume it raw without running the risk of contracting anisakiasis.
However, immediate evisceration does NOT reduce contamination related to other forms of parasitosis, including diphyllobothriasis and infestation with Clonorchiasis (Opistorchiasis) sinensis.
In diphyllobothriasis the pathogenic organism is the Diphillobothrium Latu, also commonly referred to as the "tapeworm" of fish. Man becomes infected exclusively by feeding on larvae plerocercoids (hence evolved) contained in the meat of sick fish such as salmon; what leaves you speechless is that: for every man infected by Diphillobothrium Latu up to 1,000,000 eggs are expelled with feces ... which will subsequently infest small crustaceans of river courses exponentially renewing their reproductive / evolutionary cycle.
Clonorchiasis disease (Opistorchiasis) sinensis is caused by a flat worm that can infest the blood, lungs and liver of mammals. It, like most parasites, is characterized by the different and specific evolutionary forms, which vary from one animal species to another (hosts). C. sinensis it is given by the probability that these organisms, once ingested, manage to sneak into the bile ducts and damage (even irremediably) the human liver. These are very common species in Asia (therefore in China, Korea, Japan and part of South-East Asia) where it is estimated that about 80 million people, more or less severely, are infected with them.
With regard to microorganisms, by eating raw fish NOT spoiled or secondarily contaminated, the risk of contracting bacterial food infections is rather reduced.
NB. There are extremely serious forms of toxic contamination from marine algae; these mainly concern large fish (barracudas, jacks, etc.) which accumulate large quantities of them inside the meat and organs. However, these are typical intoxications of the tropical hemispheres.
Nutritional aspects of fishery products
Fish and fishery products boast all the nutritional characteristics typical of the 1st food group (SINU classification). Among these are mainly highlighted:
- High biological value proteins, on average 16-20% (of the raw weight)
- Presence of saturated lipids, variable quantities of cholesterol (especially in eggs, bivalve molluscs and crustaceans) and, especially in fish species of cold seas, essential fatty acids of the omega3 family (eicosapentaenoic acid - EPA - 20: 5 ω ‰ -3 ). The fat content allows a classification of fish into 3 groups:
- Lean fish: with lipid content <5% (cod or hake, sole, turbot, sea bream, bream, dogfish, emery, halibut, anchovy, tuna fillet, pike, trout, tench etc.)
- Semi-fat fish: with a lipid content ranging from 5 to 10% (sardine, carp, mullet, etc.)
- Fatty fish: with a lipid content> 10% (eel, salmon, tuna belly, mackerel, etc.)
NB. The quantity but above all the quality of the lipids contained in the fish depends VERY on the origin (farming or fishing), and if reared, on the diet (bad if made up of animal pellets and good if it contains krill shrimps because they are rich in EPA - 20: 5 ω ‰ -3)
- Negligible quantity of carbohydrates (glycogen of molluscs and crustaceans)
- Absence of dietary fiber
- Excellent supply of B vitamins
- Excellent supply of trace elements including above all iron (Fe - in sea bass, corvina, mussels, etc.), phosphorus (P), iodine (I); there is also a high intake (at the discretion of the animal family) of sodium (Na).
NB. Consuming fish helps prevent cardiovascular diseases thanks to the EPA content - 20: 5 ω ‰ -3 and helps to moderate the energy intake of the diet.
Raw Fish Video Recipes
Ceviche is a Peruvian recipe based on marinated raw fish
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- Go to the Video Recipes Section
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Other recipes based on raw fish: tuna carpaccio, tuna tartare
SUSHI - RAW FISH
In this video presentation on sushi it is clarified how to prepare and consume raw fish for sushi in total safety (1:50 minute)
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Raw fish VS cooked fish
The substantial differences between the consumption of raw and cooked fish are:
- Maintenance of the structural integrity, therefore of the functionality of the EPA - 20: 5 ω ‰ -3 in raw fish compared to cooked fish; these fatty acids are extremely thermolabile, therefore, avoiding or reducing the heat treatment allows the absorption of a greater quantity of nutritionally useful essential fatty acids.
- Improvement of digestibility in products moderately cooked than raw (especially cephalopod molluscs: octopus, cuttlefish, squid, baby octopus, squid, etc.)
- Maintaining the integrity of the thermolabile vitamins; among these, the molecules that most undergo heat treatment are: thiamine (vitamin B1), riboflavin (vitamin B2), pantothenic acid (vitamin B5) and tocopherol (vitamin E) . On the other hand, retinol and its equivalents (vitamin A and β-carotene) are less damaged. Almost absent, therefore negligible, ascorbic acid (vitamin C).
The advantages of eating raw fish are admirable but absolutely NOT sufficient to justify their frequent consumption; as it seems obvious, the hygienic aspect that limits the administration of raw fish-based dishes cannot be ignored and ignoring it would constitute a serious risk for one's health and the collective one. It is true that essential fatty acids ω ‰ 3 are distributed heterogeneously in food and their integrity should, together with that of vitamins, be preserved as much as possible; however, increase the risk of contracting serious diseases and at worst disabling or fatal (intestinal resection for anisakiasis, cirrhosis of the liver due to C. sinensis, typhoid fever, cholera, viral hepatitis, etc.) does not represent reasonable behavior. Rather, it is advisable to increase the consumption of fish in order to ALWAYS guarantee the intake of essential fatty acids ω ‰‰ 3 and thermolabile vitamins (among other things, better distributed in food than EPA 20: 5 ω-3 ).
- Clinical Nutrition Manual - R. Mattei - Medi-care - pages 155-156
- Food microbiology - James M. Jay, Martin J. Loessner, David A. Golden - Springer - pages 745-746