What is better ... tuna or sardines?

What are the most prominent nutritional benefits provided by each of them?

Are there specific caveats?

The answers are in this comprehensive report.

The answer to the first question quickly is that sardines are generally better than tuna, especially for pregnant women and young children.

According to nutritionist Julia Zumbano, at the Cleveland Clinic, sardines offer a variety of benefits, as they are a great source of omega-3 fatty acids.

Sardines provide 2 grams of heart-healthy omega-3 fatty acids, per 3-ounce serving (85 grams) of sardines, and contain one of the highest levels of omega-3s and the lowest levels of mercury of any fish.

Sardines also provide the body with calcium and vitamin D, thus supporting bone health.

Sardines only feed on plankton, which means that they do not contain the high levels of mercury found in other fish.

Heart disease

Omega-3 fatty acids help prevent heart disease due to their anti-inflammatory properties, and omega-3 fatty acids may reduce the risk of blood clots and lower blood pressure.

Sardines are an excellent source of vitamin B12, and this vitamin aids the cardiovascular system and gives you energy.

Sardines are an excellent source of calcium, and this makes them a good choice for calcium for people with lactose intolerance.

Sardines contain niacin (vitamin B3), iron, potassium, magnesium, zinc and phosphorous, and provide the body with essential protein to build healthy muscles and the immune system.

And when buying canned sardines, it is best to purchase bottled in olive oil rather than soybean oil.

There are also canned sardines in water, which is a good option to reduce their fat content.

Tuna

Nutritionist Julia Zumbano says fresh tuna is a great source of omega-3s, but there is a risk of exposure to mercury poisoning, and this also applies to canned tuna.

Because tuna is high in mercury, pregnant women and young children should consult a doctor before eating it.

Exposure to high levels of mercury increases the risk of cognitive defects and other health problems.

According to the US Food and Drug Administration (FDA), mercury is a naturally occurring element in the environment that is also released into the atmosphere through many types of human activity. It can collect in streams, lakes, and oceans, and convert to methylmercury in water or sediments. This type of mercury is found in fish, and methylmercury can be harmful to the brain and nervous system if a person is exposed to too much of it over time.

Almost all fish contain few traces of the methylmercury they absorb from the food they eat, and some types of fish tend to accumulate more than others.

"The same goes for canned light tuna unless you buy it from a company that checks mercury levels in every can," Zombano says, "but very few companies are taking this extra step now."

The US Food and Drug Administration recommends about two or three servings per week of light tuna, or only one serving per week of white tuna (also known as Albacore tuna), due to the high mercury content in white tuna.

A serving of tuna for an adult weighs about 4 ounces (about 113 grams).

And since canned tuna contains less mercury than fresh tuna, it may be a better option for some people.

Canned tuna is always cooked in advance and can be eaten directly upon opening.

However, tuna has many benefits. It is an excellent source of vitamin B12, an essential vitamin necessary for making DNA, as well as aiding in the formation of red blood cells and preventing the development of anemia.

Tuna also contains iron, vitamin B6, potassium, selenium and iodine.

And tuna may help you lose weight, because it is low in fat, contains protein and low in calories, which means that it may induce a feeling of fullness and satiety for a longer period, and then reduce the intake of more food.

The health benefits of the omega-3 fatty acids in sardines and tuna generally include:

  • Reducing the risk of heart disease. High levels of omega-3 fatty acids in tuna and sardines may help reduce the level of omega-6 fatty acids and the bad (low-density lipoprotein LDL) cholesterol that can build up in the arteries of the heart.

  • It may help improve eye health.

  • Omega-3 fatty acids may slow the growth of cancer cells and reduce inflammation in the body.