Updated: Sep 23
You've probably heard omega-3 fatty acids are good for you and your baby's brain development, and fish is an excellent source of the omega-3 fatty acids EPA and DHA.
But hey, it's not always feasible or in the budget to cook fancy salmon filets for dinner. Sometimes, we just want to whip out a can of tuna from the pantry and fix us a good ole fashioned tuna fish sandwich or salad. It's quick, it's easy, it's fairly cheap and a good source of protein, healthy fats and Vitamin D.
But I'm sure you've also heard fish may be contaminated with mercury, some fish more than others, and now you're wondering if tuna is one of them. Maybe your doctor has even told you to limit or avoid tuna while pregnant or breastfeeding.
So the big question is: Is there mercury in tuna? If so, how much and is it still safe to eat it while pregnant or breastfeeding? Is light tuna better than white, and what's the difference between skipjack, albacore, chunk light and solid white? What about tuna in oil vs. tuna in water? And does it make a difference if it's wild vs. farmed?
The Benefits of Tuna
Fish is among the healthiest foods on the planet because it contains nutrients that are otherwise hard to get from food, and tuna is no exception.
Fish, including tuna, is one of the few sources of the long chain fatty acids DHA and EPA, which are good for the eyes, the brain, to reduce inflammation and they benefit the cardiovascular system. They are said to be especially beneficial in the early months of life when baby's brain, eyesight and cardiovascular system is developing. Mom's intake of these beneficial fats matters because they do cross the placenta and transfer into breast milk!
Fish, including tuna, is also one of the few food sources of Vitamin D, and most of us are at risk of being deficient. The reason is simple: Our bodies are meant to generate most of our Vitamin D requirements in the skin through UVB ray exposure from the sun; however, we usually spend a majority of our days indoors, and when we do go outside, we typically wear clothes (unlike back in caveman days). Vitamin D is important for immune function, bone health, it fights depression, it may protect against some cancers and more.
Tuna is also a good source of protein, a 5 ounce can contains about 35 to 40 grams of high quality protein, which is more than half of what the average pregnant or breastfeeding mom needs per day!
The Problem with Tuna
The problem with tuna is that it contains mercury. Nearly all fish and shellfish do; some contain more than others (see below).
Mercury is a contaminant in water which passes through the placenta during pregnancy and, in smaller amounts, through breast milk while nursing. It can damage the nerves in the brain, spinal cord and kidneys, and large amounts should therefore be avoided.
Human activity, i.e. the burning of fossil fuels (mainly coal) and the incineration of our garbage (especially batteries, electrical cords, thermomenters etc.) plays a major role in the accumulation of mercury in our food supply, so hopefully we can gradually move toward more environmentally friendly and sustainable ways to create energy and safely recycle our waste products, although that's not the topic here.
The good news is that so far, some forms of tuna and some fish in particular still contain very minimal levels of mercury so it's safe to eat them in reasonable amounts. For those types of fish, the benefits still outweigh the risks.
Which Tuna is Best While Pregnant or Breastfeeding?
Before I begin to throw recommendations around, let me explain why some fish and tuna is lower in mercury than others.
As the mercury reaches our waters (freshwater, seawater and rivers alike), it settles in the soil on the bottom or attaches to small particles in the water. Small fish then ingest some of this methylmercury and it starts to accumulate in their tissue. Larger fish eat these smaller fish and accumulate mercury into their tissue every time they eat a small fish. Even larger fish eat these small and medium-sized fish and accumulate mercury even more.
As you can probably guess, larger and older fish contain the most amount of mercury, whereas smaller and younger fish contain less.
Therefore, large fish such as sharks, swordfish, king mackerel, tilefish and bigeye tuna should be avoided, especially by women who are pregnant or breastfeeding and by small children.
Fish such as albacore/white tuna, yellowfin tuna, halibut, carp or bluefish have shown to contain moderate levels of mercury and are therefore ok to eat in small amounts, but still not ideal.
The best choices of fish (because they contain the lowest amounts of mercury) are anchovy, salmon, catfish, flounder, haddock, herring, sardines and a few others, including skipjack/light tuna.
For a full list of fish to avoid and to choose, see here.
Skipjack tuna, sometimes sold as 'chunk light tuna' is one of the smaller types of tuna and likes to jump and 'skip' across the surface of the water. It therefore typically contains only a third of the mercury of albacore tuna and is therefore the best choice of tuna while pregnant or breastfeeding.
How Much Tuna is Safe to eat?
Women who are pregnant, breastfeeding or are trying to become pregnant shouldn't avoid tuna or other fish out of fear of exposing themselves or their offsprings to mercury. Rather, they should choose low-mercury types of fish such as salmon, herring, sardines and skipjack tuna and limit their intake to the recommended amounts.
Recommendations on tuna intake for pregnant and breastfeeding moms:
2 to 3 servings of low-mercury fish per week (one serving = 4 ounces)
Recommendations on tuna intake for children ages 4 to 7:
1 to 2 servings of low-mercury fish per week (one serving = 2 ounces)
My Recommendations for Pregnant and Breastfeeding Moms
I do recommend for pregnant and breastfeeding moms to include fish into their diets, unless there is an allergy, sensitivity or religious/ethical food restriction, of course.
Salmon, herring or anchovy is great, but canned tuna is a great option for busy moms, too. Tuna is an excellent source of the long chain omega-3 fatty acids EPA and DHA (which are difficult to get from other food sources), Vitamin D, Selenium, Protein and more.
My canned tuna of choice is wild and pole caught skipjack tuna in water. Because it is a smaller tuna species, it has less mercury than other types of tuna while still containing significant amounts of the beneficial healthy fats and nutrients.
Tuna 'in water' contains about three times more (!) healthy omega-3 fatty acids and fat soluble vitamins compared to tuna 'in oil' because the oil causes these nutrients to 'leach' into the oil, causing your healthy omega-3's to go down the drain rather than into your body and breast milk. Tuna 'in water' is therefore the way to go.
I personally prefer wild caught tuna before farm-raised because there have been some concerns in the past over PCBs (polychlorinated biphenyl) being ten times higher in farm-raised compared to wild caught tuna (1), although there is no definite conclusion to this yet. However, most importantly I feel that it's the more ethical thing to do, and it is more environmentally friendly.
My tip on Saving Money on High Quality, Canned Tuna
"But wait, wild, pole caught skipjack tuna is like $4 per can!? Who can afford that?"
Yes, high quality, sustainable food is often more expensive. But there are often ways to 'buy in bulk' to safe money. Let me show you how I do this with tuna:
I buy Wild Planet's wild and pole caught skipjack tuna in a 66.5 ounce can, drain excess water, divide the flesh into small, 4 ounce portions and freeze in small glass jars (I use baby food jars)! That way, I have about 17 portions of high quality tuna for the low-low price of just a little over a buck fifty ($1.53)! I also feel better about wasting less cans!
It's a little work, but you only have to do it once and then you have high quality tuna for a small price for months!
Want to know how to add healthy fats to your breast milk? Click here!