Fish: Is It Really That Healthy?

Fish is still recommended as a healthy food that everyone should ideally eat two to three times a week. Read with us why this advice does not necessarily make sense. Because fish can not only be contaminated with heavy metals, chemicals, medicines, and worms and thus increase the risk of disease. Fishing and fish farming are also among the most brutal and environmentally unfriendly methods of obtaining food.

Fish: Better not!

Fish has long passed its zenith as a recommended food. Although most nutritionists still recommend eating fish regularly, below we explain why it is better to stay away from fish.

heavy metals in fish

Fish is often contaminated with heavy metals, which can affect your health if you eat fish frequently. These are, in particular, arsenic, cadmium, lead, and mercury.

You can’t tell by looking at a fish whether it’s slightly or heavily stressed. The Lower Saxony State Office for Consumer Protection and Food Safety only reports exposure above the statutory maximum in a few cases, but regular exposure, even if it is below the maximum, does not necessarily have to be harmless in the long run – especially since there are other maximums (e.g Environmental guidelines – see below under mercury), which are not recognized, so do not restrict trade in the fish in question.

The investigation offices for food control and animal health in Baden-Württemberg write in their 2018 balance sheet that regional fish species can also be contaminated with heavy metals, which “in individual cases means that the goods do not comply with legal requirements and are not marketable”.

Lead and cadmium accumulate in the body

In the case of lead, organic lead compounds are considered more dangerous than inorganic lead. Of all things, the fish contains organic lead, i.e. the toxic variant. Lead is so toxic, especially for children, that there is no safe dose here. Lead can cause organ damage and learning disabilities in children.

In the case of cadmium, limit values are repeatedly exceeded in fish. Like lead, cadmium is very toxic to humans (especially to the liver, kidneys, and bones) and accumulates in the body.

The elimination of lead can be supported with artichoke extract and pectin, for example.

Arsenic in fish: toxic or harmless?

Although arsenic is toxic, it is always said that the arsenic in fish is mainly organic arsenic (arsenic betaine), which is neither metabolized nor stored in the body but is quickly excreted, so it is considered toxicologically harmless. When it comes to arsenic, there are therefore no maximum values for fish (only for rice, for example).

In contrast to the supposedly harmless organic arsenic (arsenic betaine), inorganic arsenic is problematic because it can accumulate in the body. It is considered carcinogenic. However, there are also indications that organic arsenic is also not as harmless as was thought.

Organic arsenic could also be toxic

However, a study from the USA in 2020 in the Journal of Agricultural Food and Chemistry states that many organic arsenic compounds have not yet been investigated and could therefore be harmful.

Recent toxicity studies had shown that some organic arsenic compounds are bioavailable, i.e. can be absorbed into the bloodstream and tissue and are also toxic to cells – comparable to the toxicity of inorganic arsenic, so more detailed analyzes are necessary here.

As early as 2010, a British study showed that organic arsenic (arsenic betaine) is obviously stored in the body and is not excreted as quickly as was thought. 5 volunteers had been on a special diet free of arsenic betaine for 12 days.

From toxicity studies on mice, it was known that no arsenic should be detectable in the urine after a maximum of 5 days on an arsenic-betaine-free diet. However, arsenic betaine was still found in the urine of 3 of the 5 subjects after 5 days.

This could mean that organic arsenic is also stored and can only be excreted again slowly over time, or that arsenic betaine is formed during the metabolism of other (including inorganic) arsenic compounds. Because inorganic arsenic had not been withdrawn from the special diet of the subjects. It is not yet known whether fish is harmless when it comes to arsenic.

From a naturopathic point of view, garlic (which strengthens the body’s own detoxification by increasing the glutathione level), zeolite, activated charcoal, and a good supply of folic acid can help before exposure to arsenic.

Aluminum migrates from the packaging into the fish

Aluminum is not a heavy metal, but it is one of the harmful metals and is commonly found in fish. On the subject of aluminum in fish, a paper from 1997 states that fish caught close to the coast in particular is contaminated with aluminum (because of port pollution). However, the problem of aluminum pollution from the aluminum in packaging materials is greater. In any case, this problem still seems to exist today, especially with canned fish, as a study from 2020 showed. It showed that aluminum and tin could be found in 100 percent of the examined canned fish samples.

Plasticizers in fish

In addition, not only aluminum can migrate from the cans into the fish, but also other packaging chemicals, e.g. B. Bisphenol-A (in almost 10 percent of the samples examined), a hormone-active softener that can contribute to hormone disorders. However, all values were below the EFSA limit values.

Interestingly, according to studies, soy can compensate for the hormone-damaging effect of bisphenol-A, making a delicious “fish” dish made from soy an excellent alternative.

Mercury: one of the biggest health threats

Mercury is classified by the World Health Organization (WHO) as one of the top ten threats to human health. At the same time, fish is considered to be the most important source of mercury for humans.

With mercury – as with lead – it is the organic compounds (e.g. methyl mercury) that are considered dangerous because they can accumulate in the body and also in the brain. The mercury in fish is 70 to 100 percent methylmercury, i.e. organic and therefore toxic mercury.

No mercury fish for pregnant women and children

The EFSA ( European Food Safety Authority ) explains that small children, children, and women of childbearing age (pregnant and breastfeeding women of course anyway) should look out for fish species with a low methylmercury content. In pregnant women, methylmercury can impair the neurological development of the unborn child. The same is true for children, as the brain is still developing after birth and can be damaged by mercury.

Mercury levels in fish vary widely

The mercury content in fish can vary greatly depending on the fish species, with predatory fish generally being more heavily burdened (e.g. tuna, cod, mackerel, pollock, salmon) because they already eat the food they eat (small fish, crabs, shrimp). absorb accumulated amounts of mercury there and continue to accumulate in itself.

Mercury Highs

Maximum levels of mercury in fish and fishery products have been in force in the EU since 1993. It is 500 µg/kg. As is so often the case, the limit values are adjusted to the circumstances. Therefore, fish, which is generally the most contaminated (halibut, shark, swordfish, eel, also received a higher limit value – otherwise no one would have been able to eat it, namely 1000 µg/kg. However, there are still stricter EU directives on environmental quality standards, according to which fish should not contain more than 20 µg of mercury per kg fresh weight.

The latter is then of course also exceeded more frequently, e.g. B. in a study by the Austrian environmental protection organization Global 2000 from 2014. Here, 6 of the 8 fish samples examined from Austria’s lakes and rivers showed higher values, such as char, brown trout, whitefish (Lake Constance), and carp.

However, trade is not interested in the environmental directive, as fish is considered ok if it stays below the limits mentioned above (500 µg/kg), which are 25 times higher than the environmental directive.

Chronic diseases caused by heavy metal pollution

Even if it is always said that the contamination of fish is generally below the limit values, it must always be taken into account that limit values are adjusted to the current situation and that even low levels of heavy metal contamination can have far-reaching consequences if they regularly enter the body and accumulate there can enrich.


It was not until December 2021 that scientists warned that even low levels of heavy metal exposure could promote arteriosclerosis so that heavy metals can be considered a contributory cause of the most common cause of death of our time – cardiovascular diseases.

Heart diseases

Earlier studies from 2008 had already shown that mercury, even in small amounts, increases oxidative stress in the body, impairs the function of the blood vessel walls, and could thus contribute to cardiovascular problems.

A 2003 study showed that fried fish and fish sandwiches increased the risk of coronary artery disease. Only fried and baked fish reduced the risk of heart disease in this older study. To do this, however, the fish had to be eaten at least three times a week.

A more recent study (from 2011 with almost 85,000 women) showed that eating fried fish once a week is enough to damage the heart. The risk of heart failure increased by 48 percent. Baked or boiled fish, on the other hand, could reduce the risk of heart failure by 30 percent. However, it had to be eaten at least five times a week.

Amyotrophic Lateral Sclerosis

A study published in 2017 found a link between mercury in fish and ALS. Well-known ALS patients were the artist and painter Jörg Immendorff and the physicist Stephen Hawking.

ALS is Amyotrophic Lateral Sclerosis, an incurable disease of the nervous system that progresses slowly, leading to paralysis and eventually death by asphyxiation (because later the respiratory muscles are also affected by the paralysis). In the study mentioned, the group with the highest fish consumption also had the most ALS sufferers.

Thyroid diseases

Since mercury has a hormone-disrupting effect, the heavy metal can also be partly responsible for widespread hypothyroidism. It is interesting that people who suffer from an underactive thyroid gland are advised to eat more fish since fish provides iodine and an underactive thyroid gland can also be the result of an iodine deficiency. But if you unknowingly eat a lot of fish containing mercury, you can possibly make your symptoms even worse.

A 2021 Australian study states:

“The amount of mercury in the atmosphere has been steadily increasing since the 1950s, mainly from coal burning, but also from the gold mining industry, chlorine production, and waste incineration. The mercury passes from the atmosphere into the oceans and from there into the fish. We found that mercury is often stored in thyroid tissue, so this could also explain the increasing variety of thyroid diseases.”

It is therefore safer with regard to the thyroid gland (especially if thyroid disease is already present) to ensure iodine supply without fish, for example with the help of iodine drops or iodine capsules from organic kelp or by choosing other foods containing iodine.

Autoimmune diseases

Autoimmune diseases could also be caused by mercury exposure. Studies have shown that the more mercury there is in the body, the more autoantibodies there are in the body.

Other contaminants in fish

Fish does not only contain (heavy) metals and plasticizers. Fish is also contaminated with so-called POPs (persistent organic pollutants). These are pollutants that are difficult to degrade in the environment, e.g. B. flame retardants, dioxins, or some insecticides that may have long been banned, but still circulate in the environment, z. B. DDT, chlordane and dieldrin.

According to a 2016 study, these pollutants in fish can make the body’s own detoxification more difficult, as we explain in the dedicated article. So they poison directly – and indirectly because they block the poison discharge.

Carcinogenic substances and heavy metals accumulate in the fish (methyl mercury, chlorine compounds, dioxin, etc.) and sometimes have a long half-life in the human body, so they are often only broken down after months or years. You would have to keep taking long breaks from fishing so that the organism can recover from the fish pollutants and slowly break them down. However, if fish is eaten non-stop, the high intake of these substances can no longer be fully eliminated because new pollutants with long half-lives keep arriving.

Researchers studied chlorinated hydrocarbons (very toxic, accumulate, and are slow to break down) in farmed and wild salmon. Farmed salmon contains more of these pollutants because it receives correspondingly contaminated feed (fish meal and fish oil). Fish feed in Europe contained more pollutants than fish feed in North and South America.

Microplastics in fish

Of course, microplastics are not only ubiquitous in the seas, but also in fish, which ingest the microplastics with their food. According to a 2021 study, microplastics have been found in most of the fish species most commonly caught for human consumption (e.g. Atlantic cod, European hake, red mullet, European sardine).

Microplastics can have negative effects on human health. It can trigger or intensify inflammatory processes or immune reactions.

Drugs in fish

Since farmed fish in aquaculture are kept in a very small space – just like in factory farming on land – diseases and parasites and therefore also medicines (antibiotics and agents against parasites and fungal diseases) are of course the order of the day.

Illegal drug residues

In 2015, Der Spiegel wrote, “The federal government has alarming figures on antimicrobial drugs in farmed fish and crustacean products. In investigations between 2005 and 2015 as part of the European Rapid Alert System for food, the federal auditors reported evidence of pharmacologically active substances in 183 cases.” This corresponded to 6 percent of the samples taken.

It was mainly residues of malachite green, a substance that has actually only been permitted for the treatment of ornamental fish since 2004 since it can have a carcinogenic effect on humans. However, degradation products of various antibiotics and antiseptics were also found. In the case of crustaceans, 306 such finds were reported in Germany. In particular, salmon, trout, and shrimp from aquaculture were examined.

Vaccinations for fish in aquaculture

You can’t read anything about this on the website of the Federal Office for Consumer Protection and Food Safety. On the contrary. Only small residues are now officially reported. There could be several reasons for this. Either you don’t want to say anything about residues (unless the mirror is behind it) or the vaccines used are showing an effect. Because there have long been vaccines for fish, diseases do not occur in the first place and the use of medicines can be reduced.

If you are wondering how fish are vaccinated, there are several ways to do it. The safest is the injection. For this purpose, the fish (only possible with fish that are heavier than 50 g) are stunned and injected individually into the abdominal cavity. A vaccination team of four manages 5,000 salmon per hour.

Of course, DNA vaccines are also used here. It is regularly boosted and – as with vaccines for humans – vaccines for fish can also contain adjuvants (additives to enhance the vaccination effect).

So maybe in the future, we should look out for residues of these adjuvants in fish and less for medicines?

Worms in sushi can be dangerous

More and more fish suffer from worm infestation, e.g. B. among herring worms (Anisakis). The name suggests that only herring have to deal with the parasites. In fact, up to 70 percent of herring are infested with Anisakis. But not only! Herring worms are found in more than 70 species of fish – and the trend is increasing.

The white worms are usually found in the innards of the respective fish. Only after their death/catch do they migrate into the muscle flesh and are then eaten by humans.

Since the worms are killed during cooking, frying, smoking, and freezing (colder than -20 degrees), there is a risk of infection only when eating raw fish (if it was not previously frozen). The corresponding disease is called anisakiasis (herring worm disease). It is mainly found in Japan – because a lot of sushi, i.e. raw fish, is eaten there, but with the increasing popularity of sushi also in other regions of the world.

Now the worms may have died from freezing and cooking or frying and no longer pose a health risk, but of course, you still eat them. On the other hand, if you become infected with a herring worm while eating sushi, this can lead to inflammatory gastrointestinal problems.

In a gastroscopy, the worms must then be located and removed – but only if they have not already drilled through the intestinal wall. If this is already the case, an operation must be carried out. There is no medication against her ringworm).

Fish and seafood increase the risk of gout

Fish may also contribute to an increased risk of gout, a rheumatic disease in which the joints become inflamed due to uric acid crystals. Fish and seafood in particular are considered to be rich in purines. Purines are metabolized into uric acid, which in turn can develop into disease-causing uric acid crystals.

In a 2004 study, people who consumed the most fish and seafood had a 51 percent higher risk of gout than those who ate the least fish. Among the meat eaters, the high meat eaters had a 41 percent higher risk of gout than the low meat eaters. Eating high-purine plant foods did not increase the risk of gout.

Fish and the risk of breast cancer

There are studies that claim to have observed a reduced risk of breast cancer from eating fish, which usually makes big headlines. However, there are also other studies that have found no association between fish consumption and breast cancer risk, and even studies that indicate a possible opposite effect of fish consumption. You hardly read anything about them.

For example, a study published in the Journal of Nutrition in 2003 used data from 23,693 women (postmenopausal) to show that for every additional 25 g of fish, the likelihood of developing breast cancer increased by 13 percent. The risk was slightly higher with lean fish than with oily fish. Likewise, the risk of breast cancer was higher with processed fish (e.g., canned or smoked fish) than with boiled or fried fish.

In 2013 comes a study that was published in the British Medical Journal and was reported all over the press at the time with the headline: “Fatty fish reduces breast cancer risk”. However, if you looked at the study, it said that you could only observe a reduced risk with the consumption of marine omega-3 fatty acids (EPA and DHA). However, the consumption of fish in general did not indicate a reduced risk.

Marine omega-3 fatty acids are found almost exclusively in oily sea fish, but hardly in lean fillets. But it is precisely this that is consumed most frequently and used for most fish fast food dishes (fish fingers, fish burgers, breaded gourmet fillets, etc.).

However, marine omega-3 fatty acids are only found in fish because fish eat omega-3-rich algae or omega-3-rich small animals. The latter are only rich in omega-3 because they eat algae rich in omega-3. You can also lower your risk of breast cancer simply by eating omega-3-rich seaweed right away. These are available as algae oil e.g. B. the Omega-3 Fluid from effective nature.

Fish and the risk of glioma

According to a 2020 meta-analysis from China, consuming processed fish may increase the risk of glioma by 88 percent because processed fish may contain nitrates and nitrites. Glioma is the most common malignant brain tumor. That being said, processed meat products (when treated with curing salt) are also very high in nitrates.

Farmed salmon: not for pregnant women, breastfeeding women, and children
Farmed salmon contains significantly more pollutants than wild salmon. The main reason for this is the fish feed that is given to the farmed salmon. Researchers, therefore, advise women of childbearing age, pregnant and breastfeeding women, and children not to eat salmon from aquaculture, but rather to use other sources of protein and omega-3.

Nutrients in fish

Of course, fish isn’t all bad. It also contains valuable nutrients and vital substances, such as the following:

  • protein
  • Vitamin D
  • Omega-3 fatty acids
  • selenium
  • iodine

But now the question arises as to whether fish is so unique in terms of these nutrients and vital substances or whether there are alternatives that also provide these nutrients and vital substances and do not have the numerous disadvantages of fish (e.g Pollution, overfishing, animal cruelty).

Proteins in fish

Fish is just as little needed for protein supply as meat.

Vitamin D in fish

As far as vitamin D is concerned, fish does contain vitamin D, but only certain types of fish in relevant quantities and only if you eat them whole because fish liver in particular contains vitamin D, and fish fat also contains certain quantities.

If you wanted to cover your vitamin D requirement with fish alone (there are no other foods with relevant amounts of vitamin D), you would have to eat a good kilogram of the fish richest in vitamin D per week, but this is already in view of the ecological Consequences (if everyone ate that much fish weekly) is not justifiable, nor is it necessary as there are easier ways to meet your vitamin D needs.

Omega-3 fatty acids in fish

With regard to omega-3 fatty acids – essential fatty acids that must be ingested with food – the omega-3 amounts vary enormously depending on the fish species, with fish with a high-fat content not only having more omega-3 fatty acids but also often also supplies more heavy metals, because heavy metals prefer to be stored in fatty tissue.

Fatty fish include salmon, mackerel, herring, sardines, and tuna. However, tuna and mackerel in particular are often contaminated with mercury.

Refined fish oil in fish fingers and gourmet fillets

Two other very popular fish species are cod and coalfish. At 160 mg per 100 g, cod is not particularly rich in omega-3. Saithe provide at least three times the amount with 470 mg. But you would only get this higher amount of omega-3 if you ate the whole fish and not just the fillet.

However, the most popular pollock products – fish fingers, gourmet fillets, and the like – are made from the low-fat fillet and therefore only contain around 200 mg of omega-3 fatty acids because the manufacturers help with refined fish oil. This amount is only marginally enough to cover the omega-3 requirement.

Omega-3 requirements depend on many factors

The German Nutrition Society finds that 250 mg of long-chain omega-3 fatty acids per day is sufficient (for adults). Other sources (WHO, NATO Workshop), on the other hand, recommend 800 to 1000 mg per day, so there is great disagreement here.

The omega-3 requirement is very individual in each case and depends on various factors. So increase z. B. a high consumption of omega-6 fatty acids, smoking, or chronic diseases clearly increases the need (to several 1000 mg). In studies, the intake of omega-3 fatty acids in the case of existing health problems usually only showed an effect at these higher doses.

How much omega 3 is in which fish?

For guidance, the following are the omega-3 values of some fish species per 100 g. Again, keep in mind that you’re only getting these omega-3 amounts if you’re eating the whole fish and not just the lean fillet:

  • Anchovies 2055 mg
  • Farmed Salmon 1530 mg
  • Herring 1450 mg
  • Mackerel 1200 mg
  • Trout 935 mg
  • Swordfish 820 mg
  • Tuna 720 mg
  • Saithe 470 mg
  • Wild Salmon 440 mg
  • Hake 240 mg
  • Cod 160 mg
  • Monkfish 120 mg

Farmed salmon with a poor omega-6 to omega-3 ratio

Farmed salmon contains one of the most omega-3 fatty acids (1530 mg), but – according to our source – at the same time almost as many omega-6 fatty acids, namely 1320 mg (due to the non-specific grain and soy-heavy feed).

We have already explained above that high omega-6 consumption increases the omega-3 requirement. Since you usually already consume a lot – if not too much – of omega-6 fatty acids with other foods anyway, you shouldn’t also eat them with fish.

Although the omega-6-omega-3 ratio in farmed salmon is still good at 1:1.15, it is not comparable to the natural ratio, e.g. B. in wild salmon from 1: 8.8 (50 mg omega 6 and 440 mg omega 3), which can compensate for an excess of omega-6 fatty acids from other foods, which is less the case with farmed salmon.

Furthermore, farmed salmon only contains high levels of omega-3 because they are fed omega-3-rich fish oil. So you could also take the appropriate food supplement yourself, saving yourself the detour via the aquaculture and the animals the horror there. Of course, you don’t have to take fish oil for this but use a high-quality algae oil.

Omega 3: It depends on how the fish is prepared

It also depends on the preparation of the fish and whether it is even able to increase the omega-3 level in the blood. Fried fish and fish sandwiches could not, according to a 2003 study. The fish had to be fried or baked.

If you use fat to prepare the fish, olive oil is a good choice. On the other hand, if you use sunflower oil, corn oil, or other omega-6-rich oil, then you unnecessarily worsen the omega-6 to omega-3 ratio.

Selenium in fish

Fish contains selenium, an important trace element that is rarely found in Europe. Because European soils are low in selenium compared to American soils, for example. So for Europeans, fish seems to be one of the few reliable sources of selenium.

Since selenium is a detoxifying trace element, e.g. B. can inhibit the accumulation of mercury in the body, nature has apparently taken the perfect precautions and at the same time provided the mercury-rich fish with a lot of selenium.

This may also partly explain why studies on the health effects of eating fish vary so much – positive (when the fish contains enough selenium to inhibit mercury) and negative (when the fish is low in selenium or contains too much mercury in relation to its selenium content). , because too much mercury in turn inhibits selenium absorption).

How much selenium is in which fish?

In the list below you will find the selenium content per 100 g of some types of fish. It is notable that fish generally contains between 40 and 70 mcg of selenium per 100 g – except for fish fingers, which contain only 17 mcg of selenium but are particularly commonly consumed. (The selenium requirement of an adult is around 70 µg per day; for detoxification, however, preparations with 200 µg are usually taken, e.g. the selenium yeast capsules of effective nature).

  • Tuna 73 mcg
  • Anchovy 68 µg
  • Swordfish 62 mcg
  • Mackerel 52 µg
  • Halibut 47 µg
  • Herring 47 µg
  • Wild Salmon 46 µg
  • Charcoal/saithe 43 µg
  • Farmed salmon 41 µg
  • Cod 38 µg
  • Fish fingers (frozen food) 17 mcg
  • Trout 15 µg
  • Breeding catfish 15 µg

Iodine in fish

Fish is particularly often recommended as a good source of iodine. However, not every fish contains relevant amounts of iodine. The trout, for example, only 3 µg per 100 g, which is very little considering a daily requirement of 200 µg. Sardines and salmon also only provide around 30 µg of iodine. Mackerel, tuna, and herring around 50 µg. The completely overfished cod contains higher values with 155 µg.

Sustainable fish consumption

Unfortunately, there is no such thing as sustainable fish consumption – as you can read in our article Ecocatastrophe Fish. The only sustainable consumption decision is, therefore, a plant-based diet, i.e. a diet without fish, meat, eggs, and dairy products – in short: a diet without suffering and with the least possible damage to the environment while at the same time having the best possible impact on human health.

Avatar photo

Written by Bella Adams

I'm a professionally-trained, executive chef with over ten years in Restaurant Culinary and hospitality management. Experienced in specialized diets, including Vegetarian, Vegan, Raw foods, whole food, plant-based, allergy-friendly, farm-to-table, and more. Outside of the kitchen, I write about lifestyle factors that impact well-being.

Leave a Reply

Your email address will not be published. Required fields are marked *

Harmful Ingredients In Our Food

Dangerous Soft Drinks