What Happens When You Eat Tuna When Pregnant
Last Updated on September 22, 2021
Advice to pregnant women about eating tuna has changed several times over the years. If you're totally confused about tuna in pregnancy and are worried about outdated information, I hear you.
Rest assured that this page is frequently updated to reflect the current tuna and pregnancy advice in most countries, including the USA, Europe, Canada, and Australia.
Pregnant women should eat two to three portions of a variety of fish per week. This can include tuna if it's low in mercury, such as canned, light versions. Other tuna types can be safely eaten in pregnancy, but less frequently.
Now you're probably wondering "but how do I tell how much mercury is in tuna?" and whether you can eat different types, right?
In this article, you'll find out which tuna is high or low in mercury, the ways you can eat it, and a step-by-step broken down portion guide so you'll know EXACTLY how much tuna to eat safely depending on what it is and how it's served.
The main thing to remember is this – fish is an excellent food choice in pregnancy. This includes tuna if you choose lower mercury options. Fish not only provides Omega 3 long-chain polyunsaturated fatty acids but a significant number of vitamins and nutrients that are essential in pregnancy (source: PubMed).
Is Tuna High in Mercury? Which Tuna Has The Most / Least?
The table below shows mercury levels in tuna, from the lowest to the highest. It uses data compiled between 1990 and 2012 by the US Food and Drug Administration, where they tested mercury levels in commonly caught commercial fish.
Each number represents the mercury concentration mean average, in parts per million (PPM). In almost every country worldwide, the maximum allowed mercury level in commercially-sold fish is 0.5PPM (source: SGS).
Note: Safe Catch is a US brand of tuna that tests every fish for mercury and can ensure low mercury levels. You can find more about Safe Catch on my recommended pregnancy-safe foods page.
| Type of Tuna | Average PPM Mercury Level |
|---|---|
| Safe Catch Elite (read more here) | 0.04 – best for pregnancy |
| Safe Catch Wild Ahi (read more here) | 0.04 – best for pregnancy |
| Canned Light (all brands) | 0.126 – best for pregnancy |
| Skipjack (Canned / Fresh / Frozen) | 0.144 – best for pregnancy |
| Safe Catch Wild Albacore (read more here) | 0.2 – best for pregnancy |
| Canned Albacore (all brands) | 0.350 – OK in moderation |
| Yellowfin, Ahi (Fresh / Frozen) | 0.354 – OK in moderation |
| Albacore (Fresh / Frozen) | 0.358 – OK in moderation |
| Fresh / Frozen average if species unknown | 0.410 – Not recommended |
| Bigeye Tuna (Fresh / Frozen) | 0.689 – Not recommended |
| Atlantic Bluefin, Longtail, Southern Bluefin | 0.796 (source: PMC) but can be much higher in bigger fish – Not recommended |
| Pacific Bluefin, Blackfin | Almost always over 0.95 and can be much higher (source: Briloon) – Not recommended |
Bear in mind that these are averages. The bigger the tuna fish, the more likely it is to have higher concentrations of mercury.
If you're catching or buying fresh tuna fish and are able to see the size, always opt to eat steaks from smaller fish where possible.
How Much Tuna Should I Eat in Pregnancy and How Often?
How much tuna you can eat in pregnancy depends on where it is on the mercury chart above. In pregnancy, you should eat no more than:
- 8 – 12oz (225 – 340g) per week of canned light, canned or fresh skipjack tuna or other fish or seafood. If fresh, this is about 2-3 skipjack steaks. If canned, this is no more than 4 regular cans of skipjack/light tuna.
- Alternatively, you can have up to 6oz (170g) of canned or fresh albacore, or fresh/frozen yellowfin/ahi. This is about 1-2 portions of small fresh ahi/yellowfin/albacore steaks, or no more than 2 regular cans of albacore.
- You can mix and match the totals above, but not add them together. For example, if you had the maximum 4 cans of light tuna, you can't then go and eat albacore on top of that. If you had a fresh yellowfin steak, you could probably only have one can of light tuna for the rest of the week.
It's not a precise science due to variations in portion size, but if you stick to the above weights and types of tuna, you'll be fine. Some countries have slightly different information. For example, in Australia, any type of tuna is counted towards the 2-3 servings per week (source: Eat for Health).
- It's not recommended that you eat any of the higher mercury tuna types during pregnancy. This is because their mercury level can differ significantly, depending on where the fish was caught and how large the fish was. A one-off bluefin tuna steak will probably not be harmful, but it's best avoided.
Tuna Portion Sizes in Pregnancy
Remember that portion sizes vary. Canned tuna comes in all sizes, as do restaurant servings of tuna steaks. As a general guide:
- One portion of fresh tuna is about 3.5oz and should be the same size as the palm of your hand. Restaurants will often give you much bigger portions, so be aware of this and order accordingly. Also ask which species the tuna is, if possible.
- One portion of canned tuna is about 2-3oz (50-60g), or half a regular tin or can.
- One portion of tuna in a pouch is about 2-3oz (50-80g). Some pouches come in portion sizes of 2.5oz (70g), and some are larger – check the label first.
In pregnancy, you should eat a variety of fish and seafood if you can. There is no reason to avoid tuna if you eat the recommended types, but it's good to add variety to your diet. You might want to read my other articles, such as this one on shrimp and prawns, or this one on salmon, to help vary the fish in your diet.
What Happens if You Eat Too Much Tuna When Pregnant?
There is no need to be anxious or panic if you accidentally eat too much tuna in a week. There is nothing in tuna that is dangerous on its own, in moderation. Remember that fish is an excellent, nutritious food to eat in pregnancy and has many benefits.
It's the cumulative effects of mercury building up in the bloodstream that you are trying to avoid when you restrict your tuna intake. If you think you may have had too much tuna, cut down on it the following week, then follow the guidelines the rest of the time.
High levels of mercury in the bloodstream can negatively affect the baby's developing brain and nervous system (source: Mayo Clinic). However, if you stick to the recommended guidelines, you'll be getting all the benefits of fish, whilst keeping to a safe level of mercury.
Can Pregnant Women Eat Canned / Tinned Tuna?
Pregnant women can safely eat tinned or canned tuna. Pay attention to the type of tuna in the tin, and cross-reference this with the mercury chart above.
Sometimes, the label will just say 'tuna' and you'll have to read the ingredients list or find the type of tuna factory-printed on the can like this:
Remember, tuna in brine or water will be lower in calories than tuna in oil. Flavored cans of tuna are also fine in pregnancy.
If you're in the USA or Canada I recommend Safe Catch for pregnant women, as it's the brand with the lowest mercury (each fish is tested, which isn't the case with other brands).
Safe Catch also only cook the tuna once in the can, so you don't drain it, you mix the juices in and benefit from more of the nutrients in the fish. It's also the official tuna of the American Pregnancy Association, for these reasons. They've also expanded into low-mercury sardines and salmon, too.
You may also be wondering: Can I eat tuna in pouches when pregnant? Pouches of tuna are safe for pregnant women to eat.
Many of the most popular brands (Creations, John West, Chicken of the Sea and so on) have made pouches of tuna products, often flavored with other ingredients like lemon or cracked pepper. They're all safe in pregnancy if you stick to the recommended portion sizes and guidelines above.
Can Pregnant Women Eat Raw (or Seared) Tuna?
Raw tuna dishes include sushi such as tuna tataki, sashimi, nigiri, and rolls. Raw tuna also appears in dishes like tuna tartare, or the Hawaiian dish poke.
In the USA, the FDA recommends that pregnant women should avoid eating raw fish such as sushi, and that includes tuna (source: FDA). The advice is the same in Australia and New Zealand (source: NSW Food Authority). In Canada, it's a similar story – raw fish is on the 'do not eat' list (source: BCCDC).
In the UK, pregnant women are told that they can eat raw fish, so long as it's been previously frozen, as this kills parasitic worms that may be in the fish (source: NHS).
Although most tuna fish destined for sushi is frozen to kill such parasites, this doesn't kill bacteria, so you have to be somewhat careful about where you're getting the sushi from or you can make it yourself.
Bear in mind that the tuna used in sushi is hard to identify unless you ask which species it is. Some cheaper tuna sushi may use higher-mercury fish. If you're going to eat sushi in pregnancy, it's a lot safer to eat the fully cooked or veggie versions (such as the ones made with canned tuna, or cooked salmon or fish).
On the whole, if you're being super cautious, avoid raw tuna and opt for something cooked instead, or a lower-mercury fish.
Dishes That Contain Tuna & Their Pregnancy Safety
Below is a list of dishes that are commonly queried because they contain tuna. The guidelines about portions and restricting your weekly intake of tuna are the same.
Sometimes it's harder to estimate your portion size if it's mixed in with other ingredients, so bear that in mind when you're eating dishes with tuna in them.
Tuna salad (including tuna mayonnaise salads)
Tuna salad often contains mayo. It's safe if the mayonnaise is made from pasteurized egg, as most commercial ones are. You can read more about the safety of mayonnaise in this article.
Pregnant women should avoid tuna salad that is pre-prepared, for example, in a deli, or in a salad bar, where it's stored or served from open containers. This is due to the risk of cross-contamination, particularly with listeria.
Tuna Bakes or Tuna Casserole
Because the tuna is (usually) from a tin or can, and then cooked again in the oven, it's safe for pregnant women to eat a tuna bake, pasta or casserole. It's harder to judge how much tuna is in a portion, but estimate the best you can so you can add it up for your weekly intake guidance (as mentioned earlier in this article).
Tuna Sandwiches (including Tuna melts, panini, etc.)
Tuna sandwiches are fine to eat in pregnancy, including the ones with mayo in if the mayo is made from pasteurized eggs (you can read more about mayo safety here). If it's from a deli or other store, ask for the sandwich to be heated up until hot (or have a melt), as this will ensure all the ingredients in the sandwich are safer to eat.
If you want a huge list of safe sandwich fillings, then read my other article here. It includes advice on shops like Subway, too.
Grilled or seared tuna steak
Tuna steaks, traditionally, are only seared or blackened on the outside and not cooked right through. In pregnancy, you can eat a tuna steak, but it'll have to be cooked right through to be made safe. Some tips are:
- Check which species the tuna steak is – many fresh steaks are from bigger species, which might be on the higher mercury list (scroll up to find the table)
- In many countries, pregnant women are told to avoid raw seafood and this includes tuna steak that is uncooked towards the center. If you're grilling or cooking a tuna steak, cook it until it's at least 145f / 63c in the center as this will kill any pathogens. To measure this, you'll need a decent food thermometer – view my recommended ones here.
- If you're in the UK, the NHS guidelines say you can eat tuna steak that isn't cooked right through, but only if the fish has been previously frozen, to kill potential parasites (source: NHS). If it's a fresh steak, either freeze it first for at least 4 hours, or cook it right through as above.
- If you don't fancy a thoroughly cooked, drier tuna steak (and I wouldn't blame you), opt for other lower-mercury fish that still stay juice when grilled, such as salmon. You can read my other article all about salmon here.
Overall, the benefits of eating fish like tuna outweigh the small risk of consuming too much mercury in pregnancy. If you follow these guidelines, you can safely eat tuna as part of a healthy pregnancy diet.
What Happens When You Eat Tuna When Pregnant
Source: https://www.pregnancyfoodchecker.com/can-pregnant-women-eat-tuna-fish-is-it-safe/