Tuna is a lean source of protein and in many ways a healthy food. However, there are certain reasons why you might not want to eat tuna, or at least eat it only infrequently. These reasons range from nutritional factors to ethical concerns about the tuna fishing industry. Before making any significant changes to your dietary habits, you should consult your health care provider.
Flesh from most fish and shellfish contains traces of the toxic metal mercury, which can damage the developing nervous systems of infants and children. Pregnant women and young children are commonly advised to limit fish consumption. The levels of mercury present in most fish are not harmful to an average, healthy adult, according to the U.S. Environmental Protection Agency. Albacore tuna, also known as "white" tuna, has higher mercury levels than light canned tuna.
Vegetarianism or Veganism
You may choose to follow a vegetarian or vegan diet for ethical reasons, health reasons or a combination of the two. Vegans do not eat anything of animal or fish origin. Some vegetarians, referred to as pesco-vegetarians, eat fish, but many vegetarians exclude all fish from their diets.
A single can of light tuna contains nearly 600 mg of sodium. Too much sodium can have negative consequences for your health, including the development of high blood pressure or hypertension. In sodium-sensitive individuals, heavy sodium consumption increases the risk of stroke, kidney disease or heart disease. Healthy adults are recommended to consume less than 2,300 mg of sodium daily, or 1,500 mg if over the age of 50.
Certain species of tuna are at risk of extinction from overfishing, according to a 2009 Reuters report. The Atlantic bluefin tuna is severely overfished -- particularly for use in sushi dishes -- and face a real threat of extinction.
In certain areas of the ocean -- notably the Pacific off Mexico and Central America -- tuna and dolphins swim together. Commercial tuna fishing since the late 1950s is believed to have killed some 6 million dolphins, according to the Southwest Fisheries Science Center. "Dolphin safe" labeling of tuna has significantly reduced accidental dolphin deaths due to tuna fishing. However, some people refuse to eat tuna when tuna fishing causes dolphin casualties.
Canned tuna has a particularly pervasive odor and can make your home, breath or body smell distinctly fishy for some time after you have eaten the tuna. To some people, the odor of tuna is a reason not to eat it, or to choose the less odorous fresh tuna over canned.
Sushi and Sashimi: Food-Borne Illness
In sushi or sashimi dishes, tuna is often served raw or undercooked. According to MedlinePlus, consuming raw fish increases your chances of food poisoning or other food-borne illnesses.
Fishing and Farming Conditions
According to People for the Ethical Treatment of Animals, both fishing and farming practices for commercial tuna are unacceptably cruel. Mass tuna fishing causes individual fish to die slowly or to be crushed by the weight of other fish. PETA claims that tuna farms are often overcrowded, unhealthy and uncomfortable for the fish during their life span.