Mercury in Tuna: How Much Is Too Much?
Canned tuna is a fantastic staple—affordable, high in protein, and easy to work into meals. For people looking to build muscle or add calories to their diet, it’s often a go-to. But, as convenient as it is, eating too much tuna can lead to an issue that, while rare, I’ve seen happen firsthand: mercury poisoning.
I’ve known a few people who’ve experienced this—bodybuilders bulking up with tuna as a cheap protein source, or influencers who ate it daily as part of a “clean eating” routine. It’s uncommon, but it’s a real thing, and worth being aware of if you’re someone who eats a lot of tuna.
Mercury in Tuna: What You Need to Know
Mercury is a naturally occurring metal found in fish, especially in larger ones like tuna that live longer and eat smaller fish. The amount of mercury in your canned tuna depends on the type:
White (Albacore) Tuna: This type has more mercury, averaging about 0.32 ppm. The FDA recommends limiting white tuna to 1-2 servings per week (4-6 ounces per serving).
Light Tuna (Skipjack): A smaller species with less mercury, averaging 0.12 ppm, is safer for frequent consumption, with up to 3 servings per week considered fine.
For most people, eating tuna in moderation is perfectly safe. But if you’re eating it daily—especially white tuna—you could be putting yourself at risk for mercury buildup.
Signs of Mercury Poisoning
Symptoms of mercury poisoning usually develop slowly, and they might not be obvious at first. If you’re eating a lot of tuna and notice these issues, it’s worth checking in with a doctor:
Neurological Symptoms
Trouble focusing or memory lapses
Mood swings, irritability, or anxiety
Numbness or tingling, especially in your hands, feet, or around your mouth
Physical Symptoms
Weakness or trembling in your muscles
Fatigue or feeling “off”
Headaches or balance problems
Rare But Severe Symptoms
In extreme cases (again, rare), mercury poisoning can cause kidney damage or speech and coordination issues.
What to Do If You’re Concerned
If you think you’ve been overdoing it with tuna, here’s what to do:
Cut Back: Stop eating high-mercury fish (like tuna, swordfish, or king mackerel) for a while to let your levels come down.
See a Doctor: They can run blood or urine tests to check your mercury levels.
Follow Medical Advice: Severe cases might require treatment like chelation therapy to remove mercury from your system.
How to Enjoy Tuna Safely
The good news is that avoiding mercury poisoning is simple if you’re mindful of your intake. Here’s how to keep tuna in your diet without worrying:
Switch to Light Tuna: Light tuna has much less mercury than white tuna.
Mix Up Your Protein: Use tuna occasionally, but add other options like chicken, salmon, eggs, or plant-based proteins.
Stick to Guidelines: Limit white tuna to 1-2 servings per week and light tuna to no more than 3 servings.
Be Aware of Your Portions: If you’re eating tuna daily, even in small amounts, it might be time to switch it up.
My Take
I don’t want to scare anyone away from eating tuna—it’s a great, healthy food for most people when eaten in moderation. Mercury poisoning is very rare, but it can happen if you’re eating a lot of tuna over time, especially if you’re trying to bulk up or relying on it as a primary protein source.
The key is balance. If you eat tuna a few times a week, you’re probably fine. But if you’re someone who eats it every day—or if you’re thinking about doing so—just keep this in mind. Be conscious of the risks, but don’t stress about it unnecessarily. The rare cases I’ve seen were preventable with a little awareness, and that’s the takeaway here: enjoy tuna, but don’t overdo it.
