How many times a week can you eat tuna?

In this brief guide, we will answer ‘how many times a week can you eat tuna?’ Also, we will look into the nutritional profile and health benefits of tuna. Is it safe to eat? Is also discussed.

How many times a week can you eat tuna?

According to the FDA, you can enjoy 2 – 3 servings of tuna ranging within 3 – 5 ounces or 85 – 140 gm in a week. The minimum recommendation is 8 ounces of seafood (less for children) per week based on a 2,000 calorie diet. Those who are pregnant or breastfeeding should consume between 8 and 12 ounces per week of a variety of seafood from choices that are lower in mercury (1). 

A brief account on tuna

Tuna is a saltwater fish that is enjoyed all over the world. It is nutritious and considered to be an excellent source of protein, omega 3 fatty acids and vitamin B.

Tuna contains lipids, especially in the skin. Marine lipids are receiving increasing attention as a source of C20 and C22 (carbonic chains of 20 and 22 atoms) omega 3 fatty acids which have profound implications for health and disease. The unique feature that differentiates lipids of marine species from those of land animals is the presence of long chain polyunsaturated fatty acids (PUFA), namely eicosapentaenoic acid, docosahexaenoic acid and to a lesser extent, docosapentaenoic acid which are important in the prevention and treatment of cardiovascular diseases, hypertension, arthritis, other inflammatory and autoimmune disorders, and cancers (2).

Two varieties of tuna are widely available; fresh or in a more convenient form of can. Fresh tuna can be found as steaks, frozen filets, sushi or sashimi. While canned tuna is packed in water, brine or oil. No significant differences between the tuna species are observed with respect to protein, total fat, and moisture contents (2).

Chef Intro

The most common tuna species are skipjack, yellowfin, bigeye, bluefin and albacore. Skipjack is smaller in size and most abundantly fished tuna species. Most widely used in the production of canned tuna and is known as chunk, light or flaked tuna. While albacore is relatively larger in size and is referred to as ‘white meat tuna’.

What is the nutritional profile of tuna?

Tuna is an excellent source of proteins with all of the essential amino acids, omega 3 fatty acids and most vitamins and minerals, namely; calcium, phosphorus, potassium, zinc, B vitamins, selenium and choline.

The chart below briefly provides the nutrition facts of 1 can (165 gm) of light tuna.

What are the health benefits of eating tuna?

Tuna fish provides the following health benefits.

Improves heart health

Being an excellent source of omega 3 fatty acids including the DHA – docosahexaenoic acid and EPA – eicosapentaenoic acid, helps reduce levels of omega 6 fatty acids and LDL (bad cholesterol) from the body. This overall improves your heart health and also lowers the risks of cardiovascular diseases.

Many studies have demonstrated the positive effects of consuming omega 3 fatty acids, by eating fish or by supplementation, on the reduction of overall mortality, mortality because of myocardial infarction and sudden death of populations. Overall, high-density lipoprotein concentrations in the blood tend to increase, whereas low-density lipoprotein concentrations tend to decrease, in the fish-eaters compared with the non fish-eaters (3).

Reduces hypertension

Omega 3 fatty acids have anti-inflammatory properties too, that can help regulate the blood pressure. Tuna is also a source of potassium that acts as a vasodilator – helps dilate blood vessels, hence, reducing your blood pressure. 

Promotes growth and development

Being an excellent source of protein, tuna can also aid in growth and development, as proteins are the primary building blocks of the body. It is a source of high biological value and high digestibility proteins especially rich in Leucine, Valine, Tyrosine, Lysine and Tryptophan. Besides, it is a valuable source of vitamins, A, D, B1, B2, niacin, B6 and B12, which play key functions in growth, development, metabolism and control of gene expression and prevention of numerous diseases (4). 

Weight loss

Tuna is low in carbs while being high in proteins and good fats. This may result in the stimulation of a hormone called leptin – a hormone secreted from fat cells that helps regulate body weight. This fulfills your satiety and prevents you from overeating.

Improves immune system

Tuna contains sufficient amounts of vitamin C. zinc, selenium and manganese, which are considered antioxidative in nature. These act on the free radicals and help eradicate them, making them an excellent immunity booster. Se is a critical component of numerous selenoproteins in humans, some of which are important antioxidant systems (e.g. glutathione peroxidase) that actively protect against damage from free radicals and reactive oxygen species, which in turn could protect against cancer or CVD (4).

Is tuna contaminated with mercury?

Being a predator and a large fish that feeds mostly on smaller fishes, tuna fish is oftentimes found to be contaminated with mercury.

The mercury that exists in low conc. in the ocean, comes from some environmental factors and from industrial waste that often gets dumped and mixed with the ocean thus polluting it.

The smaller fish feed and thrive in such an environment that is heavily polluted. In turn, the larger fishes being in the same environment and also from the consumption of these small fishes, the level of mercury builds up in their body tissues over time.  

Mercury contamination is not common only in tuna fish but many other popular fishes are also contaminated with it like salmon, oysters, lobster and scallops. However, several studies also showed that Se may protect against the toxic effects of Hg and the highest Se levels are usually present in tuna (4).

FAO and WHO held an Expert Consultation on the Risks and Benefits of Fish Consumption in 2010 important conclusions from FAO and WHO Expert Committee were as follows: (1) the absence of probable or convincing evidence of risk of coronary heart disease associated with methylmercury; (2) when comparing the benefits of omega 3 fatty acids with the risks of methylmercury among women of childbearing age, maternal fish consumption lowers the risk of suboptimal neurodevelopment in their offspring compared with the offspring of women not eating fish in most circumstances evaluated (4). 

Is it safe to eat tuna?

Marine toxins and infectious agents including parasites (nematodes, cestodes and trematodes) and bacteria have been found in seafood products. For example, bivalve molluscs feed by filtering large volumes of seawater. During this process, they can accumulate and concentrate pathogenic microorganisms. The illnesses caused by these agents range from gastrointestinal diseases to severe poisonings (paralytic, amnesic, neurotoxic and diarrhoeic syndromes). Allergens have also been found in seafood products and are usually associated with allergy processes in sensitive subjects. However, the most concerning problem from a public health point of view is the exposure to low doses of chemical pollutant mixtures (heavy metals and organic compounds such as organochlorine pesticides, polycyclic aromatic hydrocarbons, PCB, dioxins and dibenzofurans), which can be brought by seafood consumption (4). 

Methylmercury is the form of mercury found in fishes that is associated with neurotoxicity and various neurological and physical symptoms like; memory loss, tremors, vision loss and numbness of extremities. These symptoms are more prominent in children than adults.

Because of this mercury contamination, FDA has released a list of ‘best choices of fish’ which provides a list of other fishes that are less exposed to contaminants.

FDA recommends 2 – 3 servings of fish in a week to fulfill your requirement of omega 3’s. FDA also advises consuming skipjack and canned light tuna as they have lower mercury levels and refrain from yellowfin and bigeye as they may have higher levels of mercury.

For further information on tuna, please refer here.

Conclusion

In this brief guide, we answered ‘how many times a week can you eat tuna? Also, we have looked into the nutritional profile and health benefits of tuna.

Hopefully, you found this guide helpful. If you have any questions or comments please let us know.

References