Canned tuna is a readily available and affordable source of protein, making it a staple in many diets. This article examines the nutritional value of canned tuna, exploring both its potential health benefits and associated risks to help you make informed choices about incorporating it into your diet.
Nutritional Value of Canned Tuna
Tuna, in general, is a great source of protein with a low fat and calorie count. The nutritional content of canned tuna can vary depending on whether it is packed in oil or water. Canned tuna packed in oil tends to have more calories and fat compared to canned tuna packed in water.
Here's a comparison of the nutritional content per 1 ounce (approximately 28 grams) for different types of tuna:
- Fresh Tuna: (Data needed - find)
- Canned Tuna in Oil: (Data needed - find)
- Canned Tuna in Water: (Data needed - find)
Canned tuna typically has a higher sodium content than fresh tuna. The calorie, total fat, and saturated fat content depend on whether the tuna is packed in oil or water. Checking the label is recommended since nutrient content varies between brands based on packing methods. Canned tuna in water may be higher in docosahexaenoic acid (DHA), an omega-3 fatty acid important for brain and eye health. Fresh and canned tuna are good sources of vitamin D, selenium, and iodine.
Both water-packed and oil-packed tuna provide protein and are low in saturated fat. However, tuna canned in oil is generally higher in calories and total fat.
Read also: Incorporating Fish into a Carnivore Meal Plan
Benefits of Incorporating Canned Tuna into Your Diet
Here are some of the potential benefits associated with eating canned tuna:
- Cost-Effective Protein Source: Canned tuna is an inexpensive way to add protein to your diet.
- Long Shelf Life: Canned tuna has a long shelf life, lasting for 2-5 years in your pantry, making it a convenient option for stocking up.
- Weight Management: Canned tuna is low in calories and high in protein, making it a good choice for weight loss. High-protein diets can increase feelings of fullness and reduce cravings.
- Omega-3 Fatty Acids: Tuna is a source of omega-3 fatty acids, which are beneficial for heart, eye, and brain health. Consuming canned tuna is an easy way to increase omega-3 intake.
- Vitamins and Minerals: Canned tuna provides vitamin D and selenium.
- Minimally Processed: Many canned tuna brands are minimally processed, containing only tuna, water or oil, and salt. Some brands add seasonings or broth for flavor.
Canned tuna is a convenient, low-calorie source of protein and omega-3 fatty acids.
Potential Risks and Considerations
When considering canned tuna, mercury content and sustainability are the primary concerns. There are also potential downsides, including fat and sodium content and the safety of the can itself.
Mercury Content
Mercury, a heavy metal found in water, can contaminate fish. High mercury exposure can cause health problems, including impairments to the central nervous system. Tuna may have higher mercury levels than other fish because they eat smaller fish that may be contaminated. Larger tuna varieties like bigeye and albacore tend to have higher mercury levels, while smaller varieties like light tuna and skipjack have lower levels. Canned tuna usually contains light and skipjack tuna, making it lower in mercury than fresh tuna filets.
- Adults: People who consume high-mercury fish weekly have elevated mercury levels and are more likely to experience fatigue. Limit albacore tuna intake to one 4-ounce (113-gram) serving per week due to its higher mercury content. Opt for low-mercury fish like light and skipjack tuna.
- Children: Mercury exposure is particularly toxic to a developing child’s nervous system. Children aged 2-10 can have up to 1 ounce (28 grams) of low mercury fish, including light and skipjack canned tuna, two to three times per week. Consult your pediatrician about safely introducing canned tuna to infants.
- Pregnant or Breastfeeding Women: Pregnant or breastfeeding women should avoid fish high in mercury and limit albacore tuna intake to no more than 4 ounces (113 grams) per week. The FDA says it is safe for pregnant and breastfeeding women to eat low mercury fish, such as canned tuna made from light or skipjack tuna, and recommends two to three 4-ounce (113-gram) servings per week.
Sustainability
Overfishing is a growing concern because it affects ocean ecosystems and can reduce the food supply for populations that depend on these fish. Western Pacific blue-eye tuna and Indian Ocean yellowfin tuna are vulnerable to overfishing. Look for canned tuna products with the Marine Stewardship Council (MSC) certification on the label for a more sustainable option.
Read also: Healthy Fish Recipes
Other Considerations
Canned tuna often has a higher salt content than fresh tuna. If you need to reduce your salt intake, choose brands that are lower in salt. If you are trying to lose weight, choose tuna packed in water rather than oil to avoid excess calories. Some cans contain bisphenol A (BPA), an industrial chemical used in the lining of cans. Choose BPA-free cans to avoid potential health risks. Always inspect cans for spoilage or contamination, such as dents, cracking, leaking, or bulging. If cans have these signs or the contents have an off smell or color, throw them out to avoid foodborne illness.
Choose low-mercury varieties like light or skipjack tuna, BPA-free packaging, and certification for sustainable fishing practices.
The Canning Process: Impact on Quality and Safety
Canning extends the shelf life of seafood products while preserving their quality. Canning is considered a sustainable food processing method due to the fishing methods used for key species and the lower energy costs compared to fresh and frozen fish production. However, canning can change key components, allow some contaminants to persist, and generate undesirable compounds.
Canning Process and Changes in Seafood
The canning process has improved with the adoption of Hazard Analysis and Critical Control Points (HACCP) principles and the installation of turnkey lines for efficient seafood processing. After harvesting, seafood raw materials deteriorate quickly, making preservation processes necessary. The canning process, especially the time and temperatures used during sterilization, continues to be a major research focus for minimizing time and energy consumption while maximizing quality and safety. Dynamic optimization of variable retort temperature profiles has been suggested as a more effective approach to reduce energy costs without compromising quality and safety.
The canning process and long-term storage can induce changes (e.g., browning, oxidation, nutrient loss) that may affect taste and shelf life. The type of filling medium (e.g., brine, olive oil, sunflower oil) influences sensory attributes, chemical composition, and the quality evolution of canned seafood during storage. The fatty acid profile of European eels changes during the canning process, often resembling that of the filling medium. Sterilization at 115 °C can cause up to a 7.5% loss of fatty acids in oil, while about 10% of fatty acids transfer to the tomato sauce. The filling medium influences the fatty acid profile, with increased levels of fatty acids from the oil (e.g., oleic and linoleic acids) and decreased levels of polyunsaturated fatty acids like EPA and DHA. Filling mediums, particularly brine, play a significant role in forming cholesterol oxidation products.
Read also: Choosing Fish on Keto
Regarding amino acids, the filling medium and storage significantly affect the contents depending on the specific amino acid. Sterilization does not cause changes in the essential amino acid index (IEAA). The quality of the amino acid proteins in the final product decreases in the following order: canned eels in sunflower oil > olive oil > spiced olive oil. The nutritional value does not seem to be significantly affected by these variations.
Potential Hazards in Canned Seafood
The safety of marine species is under pressure due to biological contaminants caused by global climate change, as well as the accumulation of microplastics and chemical contaminants from anthropogenic activities. Canned seafood products can present biological, physical, and chemical hazards if the raw materials are not properly monitored and/or are mishandled, processed, or stored incorrectly.
Histamine
Food safety criteria and regulations regarding histamine, the most problematic biogenic amine in canned seafood products, vary significantly among countries worldwide. Fish species associated with high potential levels of histamine typically belong to families such as Scombridae, Clupeidae, Engraulidae, Coryphaenidae, Pomatomidae, and Scombresosidae. Recent studies on canned tuna, mackerel, and sardine revealed a wide average range of histamine concentrations, fluctuating from 4.6 ± 2.8 to 98.10 ± 5.18 mg/kg, which are below the accepted limits proposed by the EC and FAO/WHO for adverse health effects. However, histamine concentrations varied widely, with maximum concentrations sometimes exceeding the legal limit (ranging from below the limit of detection (LOD) to 216.9 mg/kg). Overall, studies suggested that oil, brine, and tomato sauce fillings may increase the risk of histamine poisoning.
Allergens
Canned fish is sometimes recommended due to its benefits, as some individuals with fish allergies can tolerate it, though the exact mechanisms for this tolerance remain unknown. Parvalbumin, a thermally stable and calcium-binding protein, is the most common fish allergen. Some studies show that parvalbumin content in canned tuna varies depending on the process used. An average decrease of 25% in parvalbumin concentration was observed after the canning process of fish from the Southern Hemisphere. However, the immunoglobulin E (IgE) reactivity of parvalbumin increased after thermal treatment. The presence of parvalbumin was influenced by the filling medium, thermal conductivity, calcium content, and acidity of ingredients. Undeclared tuna allergens were classified as one of the primary reasons for commercial tuna recalls in the United States between 2002 and 2020. Canned fish products can trigger allergic reactions in fish-allergic patients due to significant IgE binding to these proteins. Canned fish products may not be safe for all fish-allergic individuals.
Marine Biotoxins
Marine biotoxins are produced by certain species of microalgae as a defense mechanism or by-product of their metabolism. Shellfish, including mussels and clams, are filter feeders that accumulate toxin-producing microalgae, making them the main route of exposure to regulated marine toxins for consumers. Fish and microalgae species from tropical and subtropical regions can also accumulate emerging toxins like tetrodotoxins and ciguatoxins, potentially posing a future risk to consumers of canned seafood products. There is limited information regarding the levels of other marine toxins in canned seafood. The canning process reduces toxin content by up to 15% and facilitates the interconversion of Pectenotoxin (PTX)-group toxins into PTX-2sa in bivalves. The health risks of marine biotoxins vary depending on heat treatment and toxin analogs.
Bisphenols
Epoxy resins used to coat the inside of cans are produced from the condensation of epichlorohydrin and BPA, forming bisphenol A diglycidyl ether (BADGE) and its derivatives. These compounds, including BPA and BADGE, can migrate from the coating into food, posing potential health risks. BPA is an endocrine-disrupting compound l…
Alternative Seafood Choices
Many health-conscious consumers have already cut back on hamburgers, steaks, and deli meats, often by swapping in poultry or seafood. Choosing seafood that's lower on the food chain - namely, small fish such as herring and sardines and bivalves such as clams and oysters - can amp up those benefits.
Small Fish
Anchovies, herring, mackerel, and sardines are excellent sources of protein, micronutrients like iron, zinc, and vitamin B12, and heart-healthy omega-3 fatty acids, which may help ease inflammation within the body and promote a better balance of blood lipids. Small fish are also rich in calcium and vitamin D. Small fish are also less likely to contain contaminants such as mercury and polychlorinated biphenyls (PCBs) compared with large species like tuna and swordfish. It's also more environmentally friendly to eat small fish directly instead of using them to make fish meal, which is often fed to farmed salmon, pork, and poultry.
Bivalves
Bivalves are two-shelled aquatic creatures that include clams, oysters, mussels, and scallops. Also known as mollusks, they're good sources of protein but are quite low in fat, so they aren't as rich in omega-3's as small, fatty fish. Bivalves contain several micronutrients, especially zinc and vitamin B12. From a planetary health perspective, bivalves are among the best sources of animal-based protein. Be aware, however, that bivalves can become contaminated from runoff, bacteria, viruses, or chemicals in the water.
Aquatic Plant Foods
You can go one step further down the aquatic food chain by eating aquatic plant foods such as seaweed and kelp. If you like sushi, you've probably had nori, the flat sheets of seaweed used to make sushi rolls. Nutrients in seaweed vary quite a bit, depending on species. Seaweed is low in calories, is a good source of fiber, and also contains iodine, a mineral required to make thyroid hormones. Similar to terrestrial vegetables, seaweeds contain a range of other minerals and vitamins.
Healthiest Canned Fish Options
Most tinned fish can be healthy, but some are more nutritious and contain fewer added ingredients and contaminants. Overall, when choosing between canned varieties of the same fish, opt for the following:
- Packed in water or extra virgin olive oil
- Lower in sodium
- Lower in mercury
- Wild or safe-caught
- Packed in a BPA-free can
Sardines
Sardines are high in protein, nutrient-dense and low in mercury. One serving or can of the average store-bought sardines packed in oil provides about:
- 200 calories
- 22 grams of protein
- 12 grams of fat
- 200-300 milligrams of sodium
Sardines are also packed with omega-3 fatty acids, vitamin D, vitamin B12, calcium, phosphorus and selenium. Sardines are one of the lowest-mercury fish you can buy and are safe to eat in moderation for pregnant women and children.
Wild Salmon
Salmon packs in protein, healthy fats, and other nutrients. According to the USDA, 3 ounces of canned sockeye salmon, without skin and bones, drained, provides about:
- 167 calories
- 23 grams of protein
- 7 grams of fat
- 300 milligrams of sodium
Canned salmon is an excellent source of protein and omega-3 fatty acids and is low in mercury. Just one 3-ounce serving of canned salmon provides 25% of the daily vitamin D requirement, plus calcium, iron and potassium. It is recommended to opt for wild-caught sockeye or pink salmon, which is more sustainable and lower in contaminants.
Light Tuna
Tuna is a convenient source of lean protein, versatile and cheap. According to the USDA, one can of the average light tuna packed in water, drained, provides about:
- 142 calories
- 33 grams of protein
- 1.5 grams of fat
- 200-300 milligrams of sodium
Canned tuna provides an impressive amount of protein and packs in other valuable nutrients, including selenium, iron and vitamin B12. Tuna is lower in fat than other popular canned fish varieties like sardines, but also comparatively lower in heart-healthy omega-3 fatty acids. Tuna can be high in mercury, so choose canned varieties that are tested for mercury and are lower than average canned tuna. These include smaller tuna species, such as skipjack, which may be sold as "light" or "chunk light." Canned albacore (white) tuna and yellowfin tuna are higher in mercury and should be eaten less.
Mackerel
Mackerel is a tasty and nutritious alternative to canned sardines, salmon and tuna. According to the USDA, one serving (a standard can or 75 grams) of canned mackerel provides about:
- 117 calories
- 17 grams of protein
- 4 grams of fat
- 200-300 milligrams of sodium
Mackerel is also rich in protein and heart-healthy omega-3 fatty acids. These nutritious fish are also packed with B and D vitamins. Choose Atlantic or Pacific chub mackerel, which are lower in mercury. Avoid king mackerel, which is high in mercury.
Anchovies
Anchovies are small but mighty when it comes to nutrients. According to the USDA, one serving (about five flat filets or 20 grams) of anchovies, packed in oil, drained, provides:
- 42 calories
- 5 grams of protein
- 2 grams of fat
- 735 milligrams of sodium
These small, oily fish are loaded with nutrients, including protein, omega-3s, calcium and selenium. Anchovies are typically salt-cured and packed in oil and are much higher in sodium compared to other tinned fish varieties, which is why the serving size is much smaller.
Canned Fish to Avoid
The FDA recommends avoiding king mackerel, bigeye tuna, marlin, shark, swordfish, tilefish and other fish with higher mercury levels. Fortunately, these bigger fish aren’t commonly sold in cans, so they are relatively easy to avoid in the canned seafood aisle. Some types of canned fish are less healthy due to the added ingredients or processing. These include canned fish that are:
- Packed in processed oils
- High in sodium
- In BPA cans
When possible, try to opt for wild or sustainably-caught fish over farm-raised or imitation varieties.
Recommended Intake
Canned fish is recommended as part of a healthy diet, but in moderation. It may be safe for some people to eat low-mercury canned fish daily. Canned fish that are higher in mercury should not be eaten daily. The recommendation for higher mercury fish is to eat it no more than once a week. Recommended seafood intake is at most 12 ounces per week. The FDA recommends that women who are pregnant or planning to become pregnant eat two to three servings of low mercury fish each week. Vary the type of seafood you eat to avoid potential mercury exposure and environmental contaminants.
Risks of Canned Fish
Canned fish is generally safe if you consume the recommended amount. Avoid canned fish if you have an allergy (or sensitivity) to fish. People on a sodium-restricted diet should limit their intake of tinned fish and opt for varieties that are lower-sodium or have no salt added. Make sure to avoid buying cans that are dented or bulging or leaking, as the product inside may be contaminated. Any unfinished canned fish should be placed in an airtight container and enjoyed within a few days.