Why should you avoid certain fishes?

Fish is one of the finest sources of protein and offers all the essential amino acids. It offers micronutrients and is mainly known for omega 3 fatty acids, i.e. EPA and DHA.

However, some types of fish contain high levels of mercury which are toxic for health and reason to avoid such species of fish.

Why can mercury be a problem?

Firstly, this heavy metal is present naturally in water, air and soil or ranges become high due to environmental factors. It can build up in the bodies of fish in the form of methyl mercury, which is highly toxic.

The amount of mercury depends upon the species and level of pollution in the environment and water source. Overall, it has been seen that larger and longer-lived fish contain the most mercury. These include shark, swordfish, fresh tuna, mackerel.

A study showed that mercury levels higher than 0.5 ppm, can raise health problems for those who eat these regularly.

Accumulation in fish and then in humans 

Eating mercury exposed fishes and shellfish can lead to serious health problems

Interesting sea plants can absorb it and when fish feed on these algae, also absorb the mercury along with it.

Predator fish contains mercury 10 times higher than the fish they consume and the process is known as biomagnification.

Therefore, eating a larger species of fish is linked to higher levels of mercury in the body.

The negative impact of mercury on Health 

It can harm the functioning of the brain and heart and studies link exposure to conditions like Alzheimer’s, Parkinson’s, autism, depression and anxiety.

Additionally, mercury exposure can increase the risk of heart attacks, increase bad cholesterol levels.

Who all are at greater risk?

Women who are about to become pregnant, or have conceived, breastfeeding mothers and young children. Foetuses, children are vulnerable to Hg toxicity, can be passed on to the pregnant mother’s foetus.

Some studies suggest that ethnic groups like Asians, pacific islanders are at greater risk due to traditionally high fish.

However, the FDA advises people to maintain a consumption limit of 2-3 servings (250-340 gm) of a variety of fish every day. Low mercury fish should be chosen such as sardines, salmon, shrimp, cod.

REFERENCES 

Burger, 2011. Mercury and selenium levels in 19 species of saltwater fish from New Jersey as a function of species, size, and season. https://www.ncbi.nlm.nih.gov/pubmed/21292311#