Can I Eat Tuna During Pregnancy?

Quick Answer

The Short Answer

You can eat tuna during pregnancy, but with important distinctions based on tuna type. Light canned tuna (skipjack) is safe at 2-3 servings per week and provides excellent omega-3 fatty acids, protein, and micronutrients that support fetal development.

Albacore (white) tuna is limited to 1 serving per week due to higher mercury content. Bigeye tuna should be avoided entirely. The key is understanding that tuna's nutritional benefits—omega-3 for brain development, 20g of complete protein per serving—come with mercury considerations.

When you choose light canned tuna and limit consumption appropriately, you safely access these benefits while protecting your baby's developing nervous system from excessive mercury exposure.

Why Tuna Matters During Pregnancy

Fish consumption during pregnancy presents a dual-natured scenario: fish species are exceptional nutritional sources, yet certain varieties accumulate environmental contaminants. Tuna specifically offers significant benefits that must be carefully weighed against mercury risks.

Nutritional benefits of tuna:

A 3-ounce serving of canned light tuna provides 20 grams of complete protein, supporting the elevated protein requirements (71 grams daily) during pregnancy. Tuna delivers omega-3 fatty acids—specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid)—which are critical for fetal brain development, retinal formation, and immune function.

Research demonstrates that adequate maternal omega-3 intake is associated with reduced risk of preterm birth and improved cognitive development in offspring.

Additionally, tuna provides vitamin D (supporting calcium absorption and immune function), selenium (thyroid and antioxidant support), vitamin B12 (neurological development), and niacin (energy metabolism).

The mercury concern:

Mercury bioaccumulates in fish tissue over time, with predatory fish (like tuna) accumulating higher concentrations than herbivorous species. Methylmercury—the organic form present in fish—crosses the placental barrier and concentrates in fetal brain tissue. The developing brain is exquisitely sensitive to methylmercury; prenatal exposure has been associated with neurodevelopmental delays, reduced IQ scores, and attention-deficit disorders.

The FDA mercury testing data from 2021 documents significant variation in mercury levels depending on tuna species and geographic origin. This variation directly informs safe consumption guidelines.

How to Safely Eat Tuna

The FDA/EPA fish advisory (2021) provides explicit mercury content data that guides safe consumption:

Practical interpretation:

A standard serving of canned tuna is 3 ounces (approximately one-half can of standard canned product). For light canned tuna at 0.12 ppm mercury:

• 2 servings per week = 6 ounces weekly = approximately one 5-ounce can
• 3 servings per week = 9 ounces weekly = approximately one and one-half 5-ounce cans

For albacore/white tuna at 0.32 ppm mercury:

• 1 serving per week = 3 ounces = approximately one-half can

Calculating cumulative mercury exposure:

The FDA establishes a reference dose (RfD) for methylmercury at 0.1 micrograms per kilogram of body weight per day. For a 155-pound (70 kg) pregnant person, safe daily intake is 7 micrograms of methylmercury. Consuming 3 ounces of light canned tuna delivers approximately 0.36 micrograms, leaving substantial room for other fish sources in weekly diet.

However, many pregnant people consume tuna multiple times weekly; cumulative exposure must be calculated. The FDA recommends maintaining a food diary if tuna consumption exceeds 1 serving per week to ensure total weekly mercury exposure remains within safe parameters.

Fish types to avoid entirely during pregnancy:

• Bigeye tuna (sushi-grade, particularly high in mercury)
• Shark
• Swordfish
• King mackerel
• Tilefish from the Gulf of Mexico

These species consistently exceed safe mercury limits and offer no benefit that justifies the risk.

Canned vs. fresh/frozen tuna:

Canned tuna undergoes processing that does not remove mercury. Nutritionally, canned light tuna offers similar benefits to fresh skipjack, with the advantage of convenience. Canned albacore provides marginally higher omega-3 content but carries the mercury burden of white tuna.

Nutritional Benefits

Tuna provides valuable nutrients during pregnancy, but understanding nutritional equivalency allows informed substitutions if tuna consumption is limited:

Lower-mercury fish alternatives:

If tuna consumption is limited due to mercury concerns, the following fish varieties contain minimal mercury and can be consumed 2-3 servings weekly:

• Salmon (fresh or canned): 0.05 ppm mercury; 1,500 mg omega-3 per 3 oz serving
• Sardines (canned): 0.013 ppm mercury; 1,500 mg omega-3 per 3.75 oz serving
• Anchovies (canned): 0.05 ppm mercury; 1,500 mg omega-3 per 1 oz serving
• Pollock: 0.067 ppm mercury; 450 mg omega-3 per 3 oz serving
• Cod: 0.089 ppm mercury; 200 mg omega-3 per 3 oz serving

These alternatives deliver comparable or superior omega-3 content at significantly lower mercury risk.

Trimester-Specific

First Trimester (Weeks 1-12): Neural tube development is occurring during this period. Adequate omega-3 intake supports neural tube closure and early neurological patterning. Light canned tuna (2-3 servings weekly) is safe during the first trimester and can contribute meaningfully to omega-3 goals. Some pregnant people experience food aversions during this period; if tuna is desired, adhere to light tuna guidelines.

Second Trimester (Weeks 13-26): This trimester is characterized by rapid fetal brain growth. Continued omega-3 intake is particularly important. Light canned tuna remains safe at the specified consumption levels. The fetal blood-brain barrier is still developing; neurotoxic exposure is best minimized by adhering to light rather than albacore tuna.

Third Trimester (Weeks 27-40): Fetal brain development continues, with particular emphasis on visual cortex maturation and dendritic arborization. Continued omega-3 intake supports these processes. Safe tuna consumption levels remain consistent with earlier trimesters. No additional restrictions apply to third-trimester tuna consumption beyond the established guidelines.

FAQ

Q: Can I eat tuna salad from a restaurant if I don't know what type of tuna was used? A: Many restaurants use albacore (white) tuna because of its culinary properties.

Request clarification about tuna type; if the restaurant cannot confirm light (skipjack) tuna, limit consumption to 1 serving per week or select an alternative protein. Restaurant accountability regarding fish sourcing is inconsistent, making proactive questioning essential.

Q: Is mercury risk truly significant during pregnancy? A: Yes. FDA testing data demonstrates that fetal mercury exposure correlates with measurable neurodevelopmental outcomes. Studies of populations with high methylmercury exposure (particularly populations consuming large quantities of predatory fish) document IQ reductions, attention deficits, and motor coordination delays. Adhering to FDA guidelines reduces this risk significantly.

Q: What about tuna steaks at sushi restaurants? A: Tuna steaks are typically bigeye tuna, which contains 0.68 ppm mercury—substantially higher than safe limits. Avoid tuna steaks entirely during pregnancy. Sushi rolls made with tuna (usually albacore or bluefin) are limited to 1 serving per week if the restaurant can confirm type.

Q: Can I get omega-3s from supplements instead of fish? A: Yes. Fish oil supplements derived from lower-mercury species (salmon oil, sardine oil) or algae-based omega-3 supplements (containing EPA and DHA) provide equivalent omega-3 benefits without mercury exposure. ACOG recommends 200-300 mg combined EPA and DHA daily during pregnancy. Supplements offer a mercury-free alternative, though whole-food sources provide additional micronutrients.

Q: How long does mercury stay in the body? A: Methylmercury has a half-life of approximately 50 days. Complete elimination typically requires 5-6 months. If mercury exposure occurs early in pregnancy, the risk diminishes as pregnancy progresses, but the highest-risk window is during early fetal brain development. Limiting exposure throughout pregnancy remains the safest approach.

Sources

• FDA/EPA Joint Fish Advice. (2021). "Eating Fish During Pregnancy: What You Should Know." Food and Drug Administration and Environmental Protection Agency.
• FDA Center for Food Safety and Applied Nutrition. (2021). "Mercury Levels in Commercial Fish and Shellfish Database." Retrieved from https://www.fda.gov/food/metals-and-your-food/mercury-levels-commercial-fish-and-shellfish-1990-2012
• National Institutes of Health. (2023). "Omega-3 Fatty Acids: Fact Sheet for Health Professionals." Office of Dietary Supplements.

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