Our takeaways
- Eating fish does make you smarter. Increasing your DHA intake by 1 gram per day would increase your child’s IQ by 1.3 points on average.
- Fish with higher DHA often contain higher mercury. Only add the fish with high DHA and low mercury to your shopping cart, especially if you are pregnant.
- There’s little difference between canned and fresh fish in terms of nutrition. Canned fish give you as much heart-healthy omega-3 fatty acids as fresh fish, and sometimes more.
The myth of “Eating fish makes you smart”
Growing up, I don’t remember how many times I’ve heard my mom or even my grandma saying “Eat more fish if you want to get smart!”. I really believed it when I was a kid until I realized that I don’t seem to be any smarter than my peers entering into adulthood. It’s either their parents also pushed them to eat more fish or this was simply a myth without scientific proof.
Then this topic faded away like many other childhood myths until recently when we started preparing for pregnancy. What we already knew is that fish oil is rich in omega-3 (some fatty acids aka DHA) which reduces our chances of heart diseases and makes our skin smoother. What we didn’t know is that “increasing your DHA intake by 1 gram per day would increase your child’s IQ by 1.3 points on average” (Expecting Better by Emily Oster). That was a light-bulb moment for the fact that eating fish does make you smart (if not for the realization that my mom and grandma didn’t lie to me).
What about Mercury?
Just as I was going to swear that I am going to make my kids eat fish too (and I will sure do during pregnancy), I paused* and wondered “What about the other side of the coin? Are there any downside of eating fish?” (*Check out the “Second-order thinking” that I mentioned in an earlier post). Turned out as I researched more into fish for pregnant women, mercury popped up as the top one concern. (Okay, guys so we can’t just devour a bunch of fish to get smart). What makes it more frustrating is that fish with higher DHA often contain higher mercury. (Seriously? why makes it so complicated? And how did mercury end up in fish anyway?)
It turns out that mercury exists naturally at low levels in rock, soil, and water. Although human activities (i.e: burning fossil fuels) have increased mercury concentration in the air (and carried down to waters), it poses little danger to living things because we can get rid of it quickly. However, as mercury goes down into the ocean, bacteria turned it into a highly toxic form called methylmercury that is absorbed by algae and tiny marine lives. That’s how it gets into fish. As you can imagine, big fish eats small fish and thus the toxic accumulated exponentially. (Learn more at: https://foodprint.org/blog/so-where-does-all-that-mercury-in-fish-come-from/).
So, the shopping list?
The basic rule of thumb: find the fish with high DHA and low mercury. To simplify, put Mercury and DHA into your X-axis and Y-axis respectively (See below), and shop for those in the green quadrant only. Pay attention to the difference between Mackerel and King Mackerel there!
Personally, we haven’t been incorporating a lot of seafood in our diet so the chart above is more than enough for us. However, if you want a fuller view of it, I also like this one from the Washington Post.
The other day when I was looking for herrings near me (Seattle, WA), I found almost no option for fresh ones. So I can’t help but wonder “Does fresh vs canned fish make any difference?“. Luckily, the simple answer is no and that is sufficient for my grocery runs. If you are interested in learning more, I found these two sources helpful: Ask the doctor: Is canned fish good for the heart? (Harvard Health Publishing) and Fancy tinned fish is having a moment — but how healthy is it? .
Learn more about PM Your Parenthood, check out the About page. Or follow us on Instagram!
Also check out more blogs here. To get bite-size parenthood wisdom like this, or save infographics for future references, follow us on Instagram (@PMYourParenthood)!
You can support me and my work by contributing a cup of coffee here 🙏:
