Is Eating Raw Fish Safe and Healthy?
Raw and uncooked fish have been eaten for decades but it does not mean that we will also follow this tradition because raw fish contain harmful micro-organisms which are health hazardous. That’s why fish must be cooked prior to consumption.
But despite these specs some people still prefer to eat raw fish. It is most common in Japanese people. They use raw fish in their dishes like sushi, sashimi and ceviche etc.
Parasitic Infections from Raw Fish:
Raw fish contains parasites which cause parasitic infections in human when eaten. Long term consumption can cause serious health effects.
Parasitic infections are one of the major health issues in many tropical countries
Therefore, you can minimize this risk by buying raw fish from trusted restaurants or suppliers that have properly handled and prepared it.
Liver flukes are a family of parasitic flatworms known to cause a disease known as opisthorchiasis. According to a scientific estimate, around 17M people worldwide, especially in Southeast Asia are affected by this disease.
Moreover, the Infections are most commonly found in tropical regions of Asia, Africa, South America, and Eastern Europe.
Adult liver flukes incubate in the livers of infected humans and other mammals, where they feed on blood. The infection symptoms include enlarged liver, bile duct infection, gallbladder inflammation, gallstones, and liver cancer
The main cause of opisthorchiasis appears to be consuming raw or improperly cooked fish. Unclean hands and dirty food preparation surfaces and kitchen utensils also play a role in spreading this disease.
Tapeworms are the largest parasite known to cause disease diphyllobothriasis in humans. According to scientific estimates, up to 20M people may be infected worldwide.
The symptom of diphyllobothriasis include fatigue, stomach discomfort, diarrhea or constipation.
They also absorb a fairly large amount of vitamin B12 from the host gut which causes vitamin B12 deficiency.
Fish tapeworms are transmitted to those people who eat raw or undercooked freshwater fish or sea fish that spawn/breed in freshwater rivers. This includes salmon.
Parasitic roundworms spend the part of their life in their host such as salmon. They are known to cause a disease called anisakiasis. This infection is most commonly in those regions where fish is eaten raw or pickled includes Japan, Scandinavia and South America.
They can’t live in humans for a long time. For this reason, if they accidentally come into their body, they get stuck into their intestinal walls and eventually die. This may cause a severe immune response which leads to inflammation, stomach pain, and vomiting.
Another family of parasitic roundworms known cause a disease known as gnathostomiasis These worms are commonly found in raw or undercooked fish, poultry and frogs in Southeast Asia, Latin America, India and, South African areas. But, this infection is rare outside of Asia.
The main symptoms of this infection are stomach pain, vomiting, appetite loss and fever. In some cases, it may cause skin lesions, rashes, itching, and swelling.
There is another reason which proves that fish is cooked before to avoid food poisoning. The major types of food poisoning that can result from eating raw and undercooked fish caused by bacteria known as Salmonella and vibrio vulnificus. The main symptoms of bacterial food poisoning include upset stomach, nausea, vomiting and diarrhea.
Vibrio vulnificus is a bacterium that lives in warm seawater fishes which includes raw oyster and shellfishes etc. According to the CDC (Center for Disease Control and Prevention) report, about 1252 people were infected with Vibrio in 2014. It is not as common as some other foodborne illnesses.
“In one report, a 71- year- old man of South Korea infected by vibrio bacteria. The infection results in fever and tormenting pain in his left hand within 12 hours of its consumption. After 2 days of suffering, he visited the hospital due to the development of severe symptoms which include blood- filled cavity on the palm of his left hand and there was also a swelling under the skin. When the doctor performed surgery, they detected this bacterium”
One study shows that about 10% of imported raw seafood and 3% of domestic raw seafood in US tested positive for Salmonella
People with weakened immune systems, such as the elderly, young children and HIV patients, are highly susceptible to infections. Therefore, these high-risk groups should avoid raw meat and fish.
Moreover, pregnant women are often advised to avoid eating raw fish due to the risk of a Listeriosis, an infection caused by bacteria known as Listeria, which may cause spontaneous abortion, premature delivery, stillbirth, infection in newborns and even cause fetal death.
At present, about 12 in every 100,000 pregnant women get infected in the US.
Raw Fish May Contain Higher Amounts of Pollutants
Some fishes contain environmental contaminants such as PCBs (polychlorinated biphenyls), dioxins and pesticides because industrial wastes are being dumped into their habitats which then accumulate in the fish. Later on, this is consumed by us and causes various harmful diseases in us such as cancer and kidney stones etc. The Dioxins found in some fishes are carcinogens and can cause nerve and liver damage. The PCBs are industrial chemicals such as mercury, lead, etc which are known to accumulate in salmon.
If fish containing these harmful pollutants are eaten, it can cause cancer. One research reveals that the amount of PCBs was 26% less in cooked salmon than in raw salmon. High intake of these pollutants can increase the risk of chronic diseases such as Type 2 Diabetes and Cancer. The FDA and EPA advise pregnant women to avoid high mercury fishes such as shark, King Mackerel, tilefish and swordfish, etc and keep their intake of fish to 12 ounces per week.
What Are the Risk of Eating Fish under high heat?
Fish which cooked under high heat may contain various amounts of heterocyclic amines
An observational studies found that high intake of heterocyclic amines with an increased risk of cancer
Another study shows that frying the fish may reduce the amount of healthy omega-3 fatty acids like DHA and EPA.
In short, nutritional quality may degrade when fish is cooked.
How to Minimize the Risks of Infections occurring from Raw Fish?
There are several ways through which you can reduce the risk of parasitic and bacterial infections.
- Freezing is an effective strategy to kill parasites but not for bacteria. That’s why it is preferable to eat fish which is been frozen from a week at -4°F
- Inspect your fish visually before consuming and make sure that it smells fresh
- Don’t keep fresh fish for too long because it contains polyunsaturated fat which rancid quickly
- Clean your hands, kitchen and kitchen utensils after handling raw fish in order to avoid cross-contaminating the food you handle afterward.
There are other ways to reduce the number of parasites and bacteria they contain include marination, brining or cold-smoking on fish. But still, these methods are not enough suitable for preventing disease.