Can You Eat Tuna While Pregnant? Safe Or Unsafe?

Tuna is a nutrient-rich source of omega-3 fatty acids and protein and is considered an iron-rich food. A 2020 review of the research found positive associations between seafood consumption (which includes tuna) in pregnancy and positive neurocognitive and milestone achievement in their children. 

However, due to mercury levels, not all tuna is safe. Some tunas, such as those on the FDA’s Good Fish Choices list, may be limited to one serving per week, while one type is banned altogether. So, can you eat tuna while pregnant safely?

Let’s look closely at why tuna is good for you, how to choose safely, and any risks associated with tuna consumption while pregnant. We will also identify types of tuna to avoid, which types should be strictly limited, and recommend the types that are best to eat.

Is Tuna Safe During Pregnancy?

The safety of tuna depends on the mercury levels identified in each type of tuna. These are grouped in a chart in the FDA’s Advice About Eating Fish publication, based on three choices: Best Choice, Good Choice, and Choices to Avoid. The best-choice list contains canned light tuna, including skipjack, while the good-choice list is limited to one 4-ounce serving per week and includes

• Albacore.
• White tuna, both canned and fresh.
• Canned and fresh or frozen tuna.
• Yellowfin tuna.

Bigeye tuna contains the highest mercury level and should be avoided during pregnancy.
Eating foods high in mercury may cause hypertension or preeclampsia maternally and cognitive or physical developmental impairments in the infant. Prenatal mercury exposure is also associated with small-for-gestational-age infants.

Benefits Of Tuna During Pregnancy

Tuna is a nutrient-dense source of omega-3 fatty acids, namely eicosapentaenoic acid or EPA and docosahexaenoic acid or DHA, protein, and several essential vitamins and minerals. These nutrients support a healthy pregnancy and optimal fetal brain and nervous system functioning, all at a low caloric cost.

Tuna’s nutritional profile for a 4-ounce serving is:

• Calories: 97.8 kcals.
• Fats: 1.08 grams.
• Protein: 21.8 grams.
• EPA: 0.029 grams (29 mg).
• DHA: .227 grams (227 mg).
• ALA: 0.002 grams (2 mg).
• Iron: 1.92 mg.
• Choline: 33.7 mg.
• Iodine: 10.66 mcg.
• Vitamin B12: 2.96 mcg.

Healthy Fats

There is no established recommended intake of EPA or DHA, only of the essential fatty acid ALA or alpha-linolenic acid, which is minimally present in tuna. The body converts ALA into EPA, an ineffective process as only about 2%–10% is converted. Because of this inefficiency, health professionals advise getting your EPA and DHA directly from food or supplements.

Most pregnant people do not get enough omega-3 fatty acids in their diet. These fatty acids are crucial for fetal neurocognitive development. For adequate omega-3 intake, two servings of Best Choice seafood per week, plus vegetable oils and supplements, are recommended.

Only about 4%–11% of DHA is converted into EPA, so getting EPA is also essential. Pregnant people need 400-550 mg of EPA and DHA daily, of which 225 mg should be from DHA.

Just one serving of skipjack tuna meets your DHA requirements, leaving the EPA requirements to be met. The total EPA and DHA still need to be improved after consuming just one serving. You need two to three servings weekly to increase your omega-3 totals of EPA and DHA.

Iron

A study on Europeans found that about 60%–100% of pregnant people had inadequate iron intake. The recommended intake for iron in pregnancy in the U.S. is 27 mg/day. One serving of tuna would provide over 7% of your daily iron needs.

Iron supports muscle metabolism, carries oxygen to the cells, and is crucial in blood cell formation. It is also essential for physical growth, nerve development, cellular functioning, and hormonal production. It is a nutrient of concern in pregnancy due to the high percentage of those with inadequate intake.

Choline

The adequate choline intake is 450 mg/day in pregnancy. However, it is estimated that 90%–95% of pregnant people are estimated to consume less than the recommended amount. One serving of tuna meets 13% of your daily choline needs.

Choline is needed for neural tube formation, brain development, and the manufacturing of lipoproteins in the blood. It enhances cognitive development in the fetus and promotes an overall feeling of well-being in the parent.

Iodine

Eat at least 220 mcg of iodine daily for a healthy pregnancy, although WHO advises 250 mcg/day. One serving of tuna provides 5% of the daily RDI for this mineral. The body uses iodine to make thyroid hormones essential for bone metabolism, brain and neurological development, and metabolic rate.

A recent 2022 study shows that iodine deficiency is relatively common in pregnancy, primarily if iodized salt is lacking in the diet. A salt container will say on its label whether it is iodized; however, many consumers need to pay attention to the type of table salt they purchase. In addition, some people may restrict sodium because of water retention; this practice is inadvisable during pregnancy.

Vitamin B12

The RDI for vitamin B12 in pregnancy is 2.6 mcg. One serving of tuna contains 2.96 mcg, which makes it a high-B12 food. A recent 2021 study found that 51% of pregnant people tested had low vitamin B12 levels.

Low B12 is associated with adverse pregnancy and infant outcomes. Such outcomes include recurrent pregnancy losses, gestational diabetes, preeclampsia, lower birth weight, cognitive impairment in the infant, adiposity, and insulin resistance.

Risks Of Eating Tuna During Pregnancy

The primary risk associated with eating tuna is heavy metal poisoning from mercury toxicity. This is why it is essential to abide by the fish advisories issued by the government, which monitors mercury levels in food products. 

Mercury is a classic neurotoxin responsible for damage to the nervous system and cognitive functioning. The risk to fetal development is extremely high, and consumers should take steps to avoid elevated mercury intake from food. Fetal blood accumulates 30%–70% more mercury than the maternal blood supply does, placing the fetus at significant risk from heavy metal toxicity.

Avoid raw tuna, regardless of its type, as it can cause food poisoning. Dishes containing raw tuna, like sushi or ceviche, may harbor listeria, a potent pathogenic foodborne bacteria.

Which Types Of Tuna Are Best?

Per the Best Choice FDA guidelines, pregnant people can eat light or skipjack tuna in 4-ounce serving sizes up to three times per week. A commercially available low-mercury, dolphin-safe, bisphenol–A–free, additive-free, and non-GMO option is also on the grocery shelves. Look for low mercury on the label.

Some seafood is safe to enjoy just read the label. To avoid mercury overload, follow the FDA government guidelines. Light canned tuna, which is usually a mixture of smaller, lower-mercury tuna fish and skipjack tuna, is on the Best Choice list along with plain skipjack.

Good Choice sources of tuna limited to one serving per week are albacore, white tuna, canned, fresh or frozen tuna, and yellow-fin tuna. Try to choose only from the Best Choice list to get the most nutrients.

Conclusion

Seafood, including tuna, can be a low-calorie, nutrient-dense source of omega-3 fatty acids, protein and nutrients. However, tuna can also contain high levels of mercury. Thus, it is essential for pregnant people to consume fish according to governmental guidelines published by the FDA and summarized in this article. Tuna, in moderation, can be enjoyed as part of a healthy eating routine during pregnancy.