Is There Such A Thing As Eating Too Much Salmon?
Fish is a great way to have light meals using proteins with less of an ecological impact than something like red meat, which has an enormous climate impact. When fish is sustainably raised or caught, it dodges a lot of these issues (not to mention the health risks too much beef can pose). And, it's certainly safer from a food-borne illness perspective than, say, undercooked chicken's potential for salmonella or campylobacter. All in all, fish doesn't have any health risks associated with it, right?
Wrong, actually. Fish certainly has health issues of its own; they're just different than those possessed by red meat. Instead, the worry with fish is a singular one: mercury poisoning. But, not all fish are equal when it comes to mercury, and some are way worse than others. Thankfully, salmon — regularly among the most popular fish in America, typically trailing only shrimp — is in the least mercury-laden category along with tilapia, lobster, scallops, and catfish ... but that doesn't mean you can eat as much as you like. At a certain point, you're still going to get mercury poisoning.
You can still get mercury poisoning from salmon, even if other fish are worse
It's important to stress that salmon isn't the worst fish you can have as far as mercury — it's not even close. Swordfish, orange roughy, and certain types of tuna fit into the worst category for mercury, while halibut, mahi-mahi, and the other tunas sit a category below them. Salmon is even better than those, residing in the best possible mercury category. As such, this fish is considered safe to eat 2–3 times per week.
Any more than that, and mercury poisoning will start to be an issue, even for something like salmon — and you really don't want mercury poisoning. Symptoms include things like pain in extremities, tachycardia, weakness, fatigue, insomnia, depression, and nephritic syndrome. You'd need to consume around 200 mg of mercury for it to be lethal, meaning you likely won't die unless you're hoovering up sockeye like Joey Chestnut downs hot dogs. But, you're not going to have a good time regardless.
You might be thinking the risks of mercury poisoning from fish are overblown, but it's easier to get than you think. Consider that actor Jeremy Piven once had to pull out of a Broadway show after displaying six times the healthy level of mercury in his system — and all of it was from eating fish.
Mercury winds up in fish thanks to human industry
It's also important to ask why fish have mercury in their systems anyway. The answer, it turns out, is that it's a product of human endeavor. Though mercury is a naturally occurring element, there's not supposed to be huge levels of it in seafood; industrial activity is to blame for that. Industries like coal plants and trash incineration kick up significant levels of mercury in the atmosphere that eventually settle in waterways — lakes, rivers, the ocean, you name it. Seafood winds up consuming it, particularly larger fish (this is why swordfish and certain species of tuna like bluefin are worse for it). Salmon are a lot smaller than the worst offenders here — hence why their levels are lower — but they're not at all immune to the phenomenon.
None of this should put you off salmon entirely; it's still one of the best choices you can make when it comes to seafood. Just be careful that you don't eat it every other day; eventually, that will catch up with you.