Reasons Why Eating Fish Is Not That Healthy

Omega-3s and other essential fatty acids are needed for cell membrane, brain and nerve health. These algae-based fats not only regulate blood pressure and blood clotting, but also aid in immune and inflammatory response. They are called “essential” because they are not made in our bodies, and so must be obtained through food. Fatty acids are normally found in salmon, sardines, mackerel and other oily fish, but are also present in plant food such as flaxseed and walnuts in the form of ALA. 

When consumed, ALA is converted by our bodies into longer-chain omega-3s EPA and DHA. One drawback is that conversion rates are slow, which is why some insist that fish oils (and by extension, fish and seafood) must be consumed for overall health. Various scientific findings and research, however, prove why it may not be the case, whether or not you are planning on going vegan/vegetarian.

Has Little Or No Effect On Heart Health

A 2018 Cochrane review found that increased intake of EPA and DHA from fish oil or fish-oil-based supplements had little or no effect on the heart. These findings are consistent with many other high-quality reviews. They also found that ALA can slightly reduce risk of cardiovascular diseases and abnormal heart rhythm.

Another 2018 review, published in the British Journal of Nutrition, found that higher intake of ALA is linked to reduced heart disease risk. All these mean that plant-based omega-3 foods are better choices for getting your daily intake of that healthy fat.

Mercury Levels

Oily fish, and fish oil supplements in particular, are shown by some studies to potentially have the opposite effect than that claimed, and instead increase heart disease risk. 

According to the American Heart Association, this might be linked to the damaging effects of methylmercury, an environmental contaminant present in fish. A study of men in Eastern Finland, where mercury levels in fish are high, found that mercury levels in their hair and the amount of fish eaten are tied to increased risk of heart-linked death.

Toxic Pollutants In Oceans 

At present, our oceans are contaminated with toxic pollutants such as the above-mentioned methylmercury, polychlorinated biphenyls and dioxins. Many of these can damage nerve function.

These toxins can accumulate as you move up the food chain, negating any supposed beneficial effects of omega-3s especially in oily fish.

Conflicting Advice 

In the U.K., pregnant women or those breastfeeding are advised to consume oily fish since the omega-3s present can aid in the development of the baby’s nervous system.

By contrast, all girls and women who are breastfeeding, pregnant or planning a pregnancy —

even those who want to have a child in the future —

are warned not to eat more than two portions of oily fish weekly.

The advice above is again linked to the pollutants in fish, which can threaten the baby’s development in the womb. Similar warnings were issued regarding consumption of shark, swordfish and marlin because they contain more mercury than other fish and mercury can also damage a developing baby’s nerves.


Aside from the pollutants in the seas and oceans, mussels, oysters and other filter-feeding shellfish can directly pose a threat to overall health when eaten raw because these accumulate bacteria and viruses from the environment.

One of these viruses is norovirus, which can cause fever and gastrointestinal issues such as vomiting, diarrhea and nausea. It is called the Winter Vomiting Bug because it is more common during the winter season, but can be caught at any time of the year. Infections easily spread, either from person-to-person contact or by touching surfaces that have been contaminated with the virus and then touching your mouth.

Though common in hospitals, nursing homes, schools and cruise ships, norovirus outbreaks can also occur in restaurants and hotels. The virus is usually mild and can last for up to two days. However, it can be fatal especially for younger children and the elderly.

Hepatitis E  

A relatively rare sickness in developing countries with better infrastructure, water supply and sanitation, hepatitis E is more common in developing countries, where it is spread through a fecal-oral route. 

However, there have been clusters of infection in developed countries not associated with travel to areas at high risk of getting the virus that are instead tied to zoonotic transmission. 

Pigs and other livestock can act as reservoirs and high levels of hepatitis E have been found in wastewater and pig manure. This highlights the danger of the virus entering watercourses before accumulating in shellfish. In other words, this infectious virus is found in animal manure, sewage water and inadequately-treated water, as well as in contaminated shellfish and animal meats.

Fish Farms

These overcrowded, non-natural pens provide over half of all fish humans consume. However, they also transmit diseases while causing water pollution. Fish pens choke marine life with organic pollutants, antibiotics and harmful chemicals. 

Farmed fish tend to have less omega-3s since these are fed with omega-6-rich vegetable oils, fishmeal and fish oils, the latter two from fish pulled out from the sea. 

Industrial-scale fishing is decimating our oceans and destroys ancient coral reefs. Because trawlers frequently plough through seabeds, marine ecosystems are collapsing, with up to 90 percent of some fish species getting wiped out, decimating many large able-bodied marine animals who depend on them. This domino effect can mess with ocean ecosystems for millenia to come. Despite loads of scientific evidence of fish feeling pain the same way mammals and birds do, the belief that fish and other seafood cannot feel pain is still prevalent. Pain is part of evolution, teaching creatures which things to avoid.


Image Naotake Murayama/Flickr