Although eating tuna has health benefits, such as the addition of omega-3 fatty acids in the body, People for the Ethical Treatment of Animals (PETA) cautions people to not eat too much because of mercury poisoning. A teenage boy was cited as an example of a person who endured mercury poisoning. The young man had difficulty concentrating and playing football because he consumed too much canned tuna.
Tuna is loaded with heavy metals because it eats contaminated fish. In turn, when humans consume larger quantities of tuna, the heavy metals are transferred to them. Heavy metals attack the heart, and studies have shown that men who have the highest levels of mercury in their blood increase their risks of heart attacks and heart disease, according to PETA.
Another side effect from consuming too much tuna is the possibility of eating diseased fish. Many tuna fish are no longer caught in open waters but instead are raised on farms. The farms are overcrowded fish pens where the tuna can catch diseases and parasites from the close quarters. Another type of tuna that can cause side effects is tuna used for sushi. PETA shared with its readers that uncooked fish could harbor bacteria that triggers food poisoning. Seafood is the number one trigger in food poisoning cases. Food poisoning can become so severe that it requires hospitalization or results in death.