Summary: Yes, you can eat canned tuna during pregnancy, but with clear limits. AESAN recommends a maximum of 3 standard cans (210 g drained) per week of skipjack tuna (Thunnus albacares) and to completely avoid bluefin tuna (Thunnus thynnus) due to its high mercury content. Albacore tuna (Thunnus alalunga) is the safest intermediate option. Data, not opinions.
Table of Contents
- The Real Problem: Mercury, Not Bacteria
- Not All Tuna Is Created Equal: Species and Mercury
- Official Limits: What AESAN, EFSA, and FDA Say
- In Practice: How Much You Can Eat Per Week
- Benefits You Shouldn't Miss Out On
- Safe Alternatives with Omega-3
- Canned vs. Fresh Tuna: Mercury Differences
- Frequently Asked Questions
The real problem: mercury, not bacteria
When we talk about canned tuna during pregnancy, the risk is not bacterial. Canned tuna is sterilized at over 115°C — there is no Listeria, no Salmonella, no parasites. From a microbiological point of view, a can of tuna is one of the safest foods a pregnant woman can eat.
The problem is methylmercury (MeHg). Inorganic mercury is released into the environment (volcanoes, industry, coal combustion), deposited in the ocean, and marine bacteria convert it into methylmercury — an organic form that bioaccumulates in the food chain. The larger and longer-lived the fish, the more mercury it accumulates.
Methylmercury crosses the placental barrier and the fetal blood-brain barrier. Excessive prenatal exposure has been associated with neurodevelopmental delays, cognitive deficits, and attention problems. The most cited studies are from the Faroe Islands (Grandjean et al., Neurotoxicology and Teratology, 1997) and the Seychelles (Davidson et al., JAMA, 1998).
But — and this "but" is crucial — the solution is NOT to stop eating fish. Fish provides omega-3 (DHA), iodine, selenium, and high-quality protein that are essential for fetal brain development. The key is to choose the right species and respect the quantities.
Not all tuna is created equal: species and mercury
| Species | Commercial name | Average mercury (mg/kg) | Adult size | Pregnancy recommendation |
|---|---|---|---|---|
| Thunnus thynnus | Bluefin tuna | 0.97-1.30 | 200-400 kg | AVOID completely |
| Thunnus obesus | Bigeye tuna | 0.68-0.89 | 80-180 kg | AVOID or maximum 1 serving/month |
| Thunnus alalunga | Albacore tuna | 0.35-0.45 | 15-30 kg | Limit to 2 cans/week |
| Thunnus albacares | Yellowfin tuna / light tuna | 0.20-0.35 | 40-80 kg | Up to 3 cans/week |
| Katsuwonus pelamis | Skipjack tuna | 0.08-0.15 | 3-8 kg | Safest option |
Skipjack tuna (Katsuwonus pelamis) is by far the species with the least mercury. It is also the most commonly used in economical canned goods. It is small (3-8 kg adult), short-lived (7-8 years), and feeds on small prey — three factors that minimize mercury bioaccumulation.
Albacore tuna (Thunnus alalunga) is the intermediate option: better flavor and quality than skipjack, with manageable mercury levels if quantities are respected.
Official limits: what AESAN, EFSA, and FDA say
AESAN (Spain, 2019): Pregnant women, breastfeeding women, and children under 10 years of age should avoid consuming swordfish, shark, bluefin tuna, and pike. For other fish, it recommends 3-4 servings per week, varying the species.
EFSA (Europe, 2012): Establishes a tolerable weekly intake of methylmercury of 1.3 µg/kg body weight. For a 65 kg woman, this is equivalent to 84.5 µg of MeHg per week. A standard can of light tuna (70 g drained) contains approximately 14-24 µg of MeHg.
FDA/EPA (USA, 2024): Classifies canned tuna (light) as a "best choice" (2-3 servings/week) and canned white/albacore tuna as a "good choice" (1 serving/week). Bluefin and bigeye tuna are in the "avoid" category.
In practice: how much you can eat per week
Let's translate all this into specific cans. A standard can of tuna contains about 70 g of drained product (a 112-120 g can includes the oil).
| Type of canned fish | Mercury per can (70g) | Maximum weekly (pregnancy) |
|---|---|---|
| Skipjack tuna in oil | ~7-10 µg MeHg | 4-5 cans/week |
| Yellowfin tuna in oil | ~14-24 µg MeHg | 3 cans/week |
| Albacore tuna in oil | ~24-31 µg MeHg | 2 cans/week |
| Bluefin tuna | ~68-91 µg MeHg | Avoid |
Practical rule: 2-3 cans of light tuna or albacore tuna per week, combined with other low-mercury fish sources (sardines, anchovies, salmon), keep you within safe limits and provide the omega-3s your baby needs.
Our canned albacore and tuna are made with hook-and-line caught fish from the Cantabrian Sea. Packed in extra virgin olive oil, without additives. Ideal for safe consumption during pregnancy.
Benefits you shouldn't miss out on
Eliminating fish during pregnancy for fear of mercury is a nutritional mistake. Studies show that the benefits of moderate fish consumption outweigh the risks in most scenarios:
- DHA (docosahexaenoic acid): Essential for fetal brain and visual development. Canned tuna provides 100-300 mg of DHA per can. The WHO recommends a minimum of 200 mg/day of DHA during pregnancy.
- High-quality protein: 26 g per 100 g — complete protein with all essential amino acids.
- Iodine: 10-15 µg per can. Essential for fetal thyroid function.
- Selenium: 60-80 µg per can (over 100% of the RDI). Selenium has a protective effect against mercury toxicity — it binds to methylmercury, forming less toxic complexes (Ralston & Raymond, Toxicology, 2010).
- Vitamin D: 2-5 µg per can. Relevant in pregnancies with low sun exposure.
A 2016 meta-analysis (Hibbeln et al., Prostaglandins, Leukotrienes and Essential Fatty Acids) concluded that mothers who consumed more than 340 g of fish per week had children with better scores in cognitive development tests than those who consumed less, provided they avoided high-mercury species.
Safe alternatives with omega-3
If you want to diversify beyond tuna:
| Fish | Mercury | DHA/100g | Recommended format |
|---|---|---|---|
| Sardines | Very low (0.01-0.05 mg/kg) | 1,000-1,500 mg | Canned in olive oil |
| Salmon (farmed) | Very low (0.02-0.05 mg/kg) | 1,200-2,000 mg | Smoked, baked, canned |
| Anchovies | Low (0.04-0.08 mg/kg) | 800-1,200 mg | In vinegar (previously frozen), canned |
| Mussels | Very low (0.02-0.05 mg/kg) | 400-600 mg | Canned, steamed |
| Small mackerel | Low-medium (0.08-0.15 mg/kg) | 1,000-2,000 mg | Canned |
Canned sardines are probably the best omega-3/mercury ratio available. Small, short-lived, with insignificant mercury levels and exceptional DHA content.
Canned vs. fresh tuna: mercury differences
A common question: does canned tuna have the same amount of mercury as fresh tuna? The answer is no, and the reason is the species.
Fresh tuna sold in fish markets is usually bluefin tuna (T. thynnus) or bigeye tuna (T. obesus) — large species with high mercury. Standard canned tuna uses skipjack tuna (T. albacares) or yellowfin tuna (K. pelamis) — smaller species with less mercury.
Practical result: a 150g slice of fresh bluefin tuna can contain 145-195 µg of methylmercury (almost double the recommended weekly limit for pregnant women). Three cans of light tuna contain 42-72 µg — clearly within the safe range.
Complete your pregnancy pantry with gourmet canned goods: sardines, albacore, mussels — all low in mercury, sterilized, and rich in omega-3.
Frequently Asked Questions
Can I eat canned tuna every day during pregnancy?
Eating tuna every day is not recommended. 3 cans of light tuna per week is the practical safe limit. In addition, varying your fish sources (sardines, salmon, mussels) ensures a more complete nutritional profile and distributes mercury exposure.
Is albacore tuna different from other tuna in terms of mercury?
Yes. Albacore tuna (Thunnus alalunga) has intermediate mercury levels between light tuna and bluefin tuna. It's an excellent option for its flavor, but limit it to 2 cans per week during pregnancy, compared to the 3 cans of light/skipjack tuna you can have.
Does the oil in canned tuna contain mercury?
In minimal amounts. Methylmercury accumulates primarily in the muscle protein of the fish, not in the fat. Draining the oil does not significantly reduce mercury exposure, but it also doesn't increase it if you consume it.
Can I eat tuna sushi while pregnant?
The risk of tuna sushi during pregnancy is twofold: mercury (if it's bluefin tuna, high levels) and parasites (anisakis, if it hasn't been previously frozen at -20°C/72h). If the restaurant complies with freezing regulations and you use a low-mercury tuna species, the risk is manageable. However, health agencies recommend avoiding raw fish during pregnancy as a precaution.
Should I worry about mercury during breastfeeding?
Yes, but to a lesser extent. Methylmercury is partially excreted in breast milk, but at lower concentrations than during pregnancy (the placental barrier is more permeable than the mammary gland). Recommendations during breastfeeding are similar to those for pregnancy, although some organizations are slightly more lenient.
Does canned tuna lose omega-3 compared to fresh tuna?
It loses some, but less than commonly believed. The sterilization process reduces DHA by 10-20% according to studies. A can of albacore tuna still provides 100-250 mg of DHA — a relevant source. If you drain the oil, you lose some of the omega-3s that have dissolved in it — consume the oil or choose canned goods in natural brine.
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