1. Heavily salted or fermented fish

Salted fish, dried fish, and certain fermented fish products are popular in many cultures due to their strong flavor and long shelf life. However, these products often contain high levels of salt and may form nitrosamines during processing or storage. Nitrosamines are compounds that have been associated with an increased risk of certain cancers when consumed in large amounts over long periods.

2. Smoked fish with prolonged or high-temperature processing

Smoked fish can be delicious, but experts caution against frequent consumption of fish that has been heavily smoked or processed at very high temperatures. This method can produce polycyclic aromatic hydrocarbons (PAHs) and other potentially harmful substances. Long-term exposure to these compounds has been linked in studies to a higher cancer risk, making this category particularly concerning.

3. Fish from polluted waters

Fish living in contaminated rivers, lakes, or coastal areas may accumulate heavy metals such as mercury, lead, or cadmium, as well as industrial toxins. Regular consumption of such fish can place extra strain on the liver and kidneys and may increase long-term health risks, including cancer.

Expert advice

Health professionals emphasize that fish itself is not the problem — the risk lies in overconsumption of poorly processed products or fish sourced from unsafe environments. Choosing fresh fish, limiting smoked and heavily preserved varieties, and paying attention to food safety sources can significantly reduce potential harm.

A balanced diet that includes a variety of protein sources, along with proper cooking methods, remains the safest approach to protecting long-term health.