Can You Eat Canned Tuna During Pregnancy? Is It Safe 2024?

The World Health Organization (WHO)^[1] lists mercury among the top ten chemicals threatening public health, exposure coming mainly through diet, specifically, fish and shellfish. Even small amounts of mercury can cause serious health problems, especially in developing fetuses and children. Their neurological development can be affected, resulting in problems in motor skills and cognitive functions such as memory, attention, and language. Mercury is why pregnant women should be cautious about seafood consumption.

In 2015, the European Food Safety Authority (EFSA)^[2] stated that seafood’s health benefits outweigh its risks when high-mercury content is limited. Thus, health authorities recommend pregnant women eat 2-3 servings (about 8 to 12 ounces) of safe seafood that are low in mercury, such as shrimp, pollock, cod, hake, and so on, but limit that which is considered high-content. Read more to learn if canned tuna is a safe option with low mercury contamination during pregnancy.

Let’s answer pregnant women’s questions about eating tuna. 

Can I eat tuna while pregnant?

Not all tuna is safe to eat during pregnancy. You should avoid raw fish, including undercooked or raw tuna. According to the EFSA^[4], canned tuna probably has lower methylmercury than fresh tuna because different sizes and/or species of tuna are used. 

Can I have canned tuna while pregnant?

According to the FDA, the safest option for tuna is light canned tuna during pregnancy, on the condition that you follow the FDA recommendations to eat 2 to 3 servings (8 to 12 ounces) in a week.

What kinds of tuna are safe for pregnant women?

According to the FDA^[5], different tuna types have different mercury content:

Canned light tuna (including skipjack) is considered one of the best options, meaning you can eat 2 to 3 servings (8 to 12 ounces) of canned light tuna per week while pregnant. 2-3 servings/week is a reasonable number to hedge your risk lower than some recommendations^[6] that say you can eat 1-4 servings/week, especially with variations in serving size.  

Pregnant women can eat albacore tuna (white tuna) and yellowfin tuna if they only eat 1 serving (4 ounces) of either albacore tuna or yellowfin tuna in a week.

Avoid eating Bigeye tuna while pregnant because it contains high levels of mercury.

According to the EFSA^[4], if pregnant women eat two portions of fish per week, one of them should not be high-mercury tuna (e.g., bluefin tuna or albacore tuna,  to avoid unacceptable mercury exposure.

All seafood, including tuna, should not be eaten raw or undercooked because it may contain pathogens and toxins. If you eat fresh/frozen tuna, make sure it is fully cooked. A bacterium very dangerous to unborn babies (even lethal!) is Listeria monocytogenes^[7], which often contaminates uncooked fish (e.g., sushi) or even cooked seafood which hasn’t been refrigerated properly. Also, just because fish is smoked, this is not a substitute for thorough cooking.

Be cautious; even the same fish species may likely have different mercury content depending on their geographic locations. That’s why the American Pregnancy Association (APA)^[8] recommends a canned tuna brand called Safe Catch Elite that analyzes mercury levels of every fish and is specifically analyzed for pregnant women and children. 

How much mercury do canned tuna contain?

According to the FDA^[9], canned light tuna contains approximately 0,1 parts per million (ppm) of mercury which is lower than the FDA limit of 1,0 ppm for mercury in fish.

Benefits of Eating Tuna During Pregnancy

Nutrition is one of the cornerstones of a healthy pregnancy. Thus, pregnant women need quality nutrients to support their baby’s development and growth. Seafood, not tuna, specifically, provides essential nutrients^[10] for the baby’s brain development and nervous system. Light canned tuna contains^[11]

• High-quality protein 

• Omega-3 fatty and omega-6 fatty acids, are essential for a child’s brain development. Omega-3 fatty acids, which are eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA), are abundant in seafood. DHA is important to the brain, retina, and sperm cells. A Cochrane review^[12] showed that the incidence of premature birth–before 37th weeks (preterm birth) and before 34th weeks (very preterm birth)–was lower in pregnant women who had been taking omega-3 supplementation. It was also indicated that the risk of infant death may be lower in babies of pregnant women who had been taking omega-3 supplementation.

• Phosphorus^[13] is important to teeth, bones, and DNA structure. Many foods contain phosphorus, including seafood.

• Selenium^[14] plays a role in DNA synthesis and thyroid hormone metabolism. Selenium also has antioxidant functions, so it is involved in protection from oxidative damage. 

• Zinc^[15] requirement increases with pregnancy because of its role in protein and DNA synthesis, both increase during pregnancy; therefore, it is important for the baby’s development and growth during pregnancy. 

• Choline^[16] has a role in early brain development. It is also needed for acetylcholine production, a neurotransmitter involved in the brain and nervous system functions, muscle control, and mood.

• Iodine^[17] is needed for healthy thyroid function. The balance of thyroid hormones is important for the baby’s brain development. Because maternal thyroid stimulation increases in pregnancy, iodine requirement increases. Good sources of iodine are dairy products and seafood. 

• Vitamin D^[18] plays a role in cell growth, protein synthesis, bone health, and immunity. Vitamin D is crucial for your babies’ bone health since it regulates blood calcium and phosphate levels, which are the main minerals of bones. Although the main source of vitamin D is sunlight exposure, seafood is one of few foods that contain vitamin D, which becomes increasingly important for people in certain geographical latitudes or who spend most of their time indoors.

• Iron^[19] and folic acid^[20] supplementation are recommended by WHO^[21] to reduce maternal iron deficiency, anemia, and low birth weight risk. The deficiency of iron also affects immunity and neurocognitive development. Folic acid, crucial in the first trimester, lowers the risk of neural tube defects, such as spina bifida.

• Vitamin B12^[22] is crucial for nervous system development since it involves the myelination of nerves to enable information transformation between neuron cells. Also, it is required for DNA synthesis and healthy blood cells. The deficiency of vitamin B12 may cause developmental delays and anemia in babies.

How Much Tuna Should You Eat While Pregnant?

The UK National Health Service (NHS)^[23] advised limiting tuna consumption during pregnancy. Pregnant women are allowed to eat less than 2 tuna steaks (equivalent to 140g cooked or 170g raw tuna) or 4 medium-size cans of tuna (equal to 140 g when drained), per week. 

According to the FDA^[24], canned light tuna (including skipjack) can be eaten 2 to 3 servings (8 to 12 ounces) per week while pregnant. 1 serving (4 ounces) of albacore tuna (white tuna) or yellowfin tuna can be eaten per week.

Always keep in mind that tuna has more mercury compared to the best options that are low in mercury, such as lobster, pollock, cod, hake, sardine, and so on. See the Food and Drug Administration (FDA)^[3] and the Environmental Protection Agency (EPA)^[3] list for all the best seafood options to eat while pregnant.

Safety Precautions

Mercury levels of tuna can vary from type to type and according to their geographical locations. If the tuna you eat has too much mercury or you eat more tuna than you should, you may experience some health problems^[25]. 

Exposure to high levels of mercury may result in

• Peripheral vision loss
• A tingly sensation generally around the mouth, hands, and feet
• Decreased movement coordination
• Speech and/or hearing and/or walking impairment
• Muscle weakness

Infants in the uterus can be exposed to methylmercury if their mothers eat fish and shellfish with high mercury levels. In infants, exposure to methylmercury may result in

• Adverse effects on the baby’s developing brain and nervous system 
• Impairments in cognitive functions and motor skills

What About Breastfeeding?

Since methylmercury, as it does in the placenta, crosses over into breastmilk^[26], all of the above precautions associated with mercury, fish, and pregnancy apply the same. Lactational transfer of methylmercury by breastfeeding is an important cause of methylmercury exposure for breastfeeding infants. 

The Bottom Line

Fish consumption is advised in pregnancy with regard to its nutritional benefits on the baby’s development. On the other hand, mercury contamination in fish poses a risk factor for pregnant women. Tuna’s mercury content can vary based on the species and/or geographical location. But you don’t need to be overly concerned if you know the safe types of tuna and the serving recommendations for pregnant women.

Pregnant women can eat 2 to 3 servings (8 to 12 ounces) of canned light tuna (including skipjack) in a week.

Albacore tuna (white tuna) and yellowfin tuna are also safe if you eat a 4-ounce portion of either albacore tuna or yellowfin tuna in a week.

Pregnant women should avoid Bigeye tuna while pregnant because it contains high levels of mercury.

Although canned tuna is convenient to eat, there are lower mercury fish you can choose while pregnant.

As always, you must also be mindful of these considerations even after pregnancy, if you’re breastfeeding.

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