Why are you not supposed to eat tuna every day?

January 13, 2026 •

4 min read

All marine organisms contain mercury, but due to a process called biomagnification, large predatory fish like tuna accumulate higher concentrations. This is a primary reason why you are not supposed to eat tuna every day, as excessive consumption can lead to mercury poisoning and other adverse health effects.

Quick Summary

This article explores the health risks associated with frequent tuna consumption, primarily due to mercury content. It details safe limits based on tuna type, explains the dangers of heavy metal buildup, and offers balanced dietary advice.

Key Points

Mercury Accumulation: Eating tuna daily increases the risk of mercury buildup in the body, a neurotoxin that can cause serious health issues over time.
Varying Mercury Levels: Different tuna species contain different amounts of mercury; larger fish like albacore and bigeye have significantly higher levels than smaller skipjack or light tuna.
Protect Vulnerable Groups: Pregnant women, breastfeeding mothers, and young children are particularly sensitive to mercury's neurotoxic effects and should strictly limit or avoid high-mercury tuna.
Nutrient Benefits vs. Risks: While tuna provides valuable protein and omega-3s, these benefits must be balanced against the risks of heavy metal exposure, necessitating dietary moderation.
Diversify Your Diet: To minimize risks, rotate tuna with other lower-mercury seafood options like salmon and sardines, and follow recommended weekly serving limits.
Check Labels: Always read the can or package to identify the tuna species (e.g., skipjack vs. albacore) and choose varieties packed in water with low or no added sodium.

The Primary Concern: Mercury Accumulation

The main reason for limiting your daily intake of tuna is the risk of mercury toxicity. Tuna, being a large predatory fish, sits high on the aquatic food chain. This position, combined with a long lifespan, means it bioaccumulates methylmercury, a potent neurotoxin. While trace amounts of mercury in a single serving are not a concern for most healthy adults, eating it daily allows this heavy metal to accumulate in your body over time.

How Mercury Affects Your Body

When absorbed by the body, methylmercury can cross the blood-brain barrier and damage the nervous system. Symptoms of chronic, low-dose mercury poisoning can be subtle and develop over time. In adults, this can manifest as:

Memory loss and difficulty concentrating
Anxiety, mood swings, and depression
Numbness or tingling in the hands, feet, or mouth
Impaired coordination and tremors
Kidney damage
Vision and hearing problems

Special Risks for Vulnerable Populations

For certain groups, the risks are more significant. The World Health Organization identifies mercury as one of the top ten chemicals of major public health concern.

Pregnant or breastfeeding individuals: Mercury can pass through the placenta and into breast milk, affecting the fetus or infant's developing brain and nervous system. Exposure can cause developmental delays, cognitive difficulties, and other serious issues.
Young children: Their smaller bodies and developing nervous systems are more susceptible to mercury's harmful effects. Recommended intake levels are much lower and depend on age and weight.

Not All Tuna Is Created Equal

The mercury content in tuna varies significantly by species. Generally, the larger and longer-living the fish, the higher its mercury level. Therefore, moderation is key, and choosing the right type of tuna is essential for minimizing risk.

Tuna Species and Mercury Content


Tuna Species	Mercury Level (Average ppm)	Recommended Adult Weekly Servings (approx. 4 oz)	Suitable for Pregnant/Breastfeeding Individuals?
Light Tuna (Canned)	0.126	2-3 servings	Yes (2-3 servings/week)
Skipjack Tuna	0.144	2-3 servings	Yes (2-3 servings/week)
Albacore Tuna (Canned)	0.350	1 serving	Yes (1 serving/week)
Yellowfin Tuna	0.354	1 serving	Yes (1 serving/week)
Bigeye Tuna	0.689	Avoid	No

*Note: Fresh/frozen tuna often has higher mercury levels than canned versions of the same species because canned varieties typically use smaller, younger fish.

Other Considerations Beyond Mercury

While mercury is the main dietary concern, other factors warrant attention when considering daily tuna consumption.

Potential for Histamine Poisoning

If tuna is not handled or refrigerated properly, bacteria can convert natural histidine in the fish into histamine. This can cause scombroid poisoning, with symptoms like flushing, headache, and diarrhea, even if the fish is later cooked. While not a risk with high-quality, properly handled tuna, a daily habit could increase the chances of encountering a spoiled product.

High Sodium Content

Many canned tuna products contain added sodium for preservation and flavor. A daily intake of canned tuna can contribute significantly to your daily sodium limit, which is especially important for those managing blood pressure or other heart conditions. Opting for "no salt added" or fresh tuna can mitigate this risk.

Microplastic Contamination

Microplastics are a growing concern in marine ecosystems, and they can be found in seafood. Studies are ongoing, but some research suggests these tiny plastic particles and the compounds they carry can accumulate in fish, including tuna. Limiting intake can help reduce potential exposure to these contaminants.

How to Enjoy Tuna Safely and Healthily

To reap the nutritional benefits of tuna—such as its high protein, omega-3 fatty acids, and essential vitamins like B12 and D—without the risks, follow these best practices:

Vary your fish intake: Don't rely solely on tuna for your seafood. Include other low-mercury options like salmon, sardines, and shrimp.
Choose the right species: Opt for canned light or skipjack tuna over albacore for lower mercury content.
Follow FDA guidelines: Adhere to the recommended weekly servings based on your personal health needs and the type of tuna consumed.
Opt for lower sodium: When buying canned tuna, choose varieties with low or no added salt to manage your sodium intake.
Complement your diet: Pair tuna meals with other nutrient-dense foods, like vegetables and whole grains, to ensure a well-rounded diet.

Conclusion: Moderation is Key

While tuna is a convenient and nutrient-rich food, daily consumption is strongly discouraged due to the risk of mercury accumulation. The level of risk depends heavily on the type of tuna you eat, with larger species like albacore and bigeye posing a higher danger than smaller species like skipjack. By practicing moderation, choosing lower-mercury options, and diversifying your seafood intake, you can safely enjoy the benefits of this popular fish while protecting your health. For more detailed information on mercury levels in various fish, consult authoritative sources like the Food and Drug Administration (FDA).

Frequently Asked Questions

Yes, canned tuna, especially white (albacore) tuna, contains higher levels of mercury than other seafood options. Canned light tuna (primarily skipjack) is generally lower in mercury.

Symptoms can include memory loss, tremors, numbness or tingling in extremities, mood changes like anxiety and irritability, and impaired coordination. These often develop from long-term, low-dose exposure.

For most healthy adults, the FDA recommends limiting canned light tuna to 2-3 servings per week and canned white (albacore) tuna to 1 serving per week. Pregnant women and children have stricter limits.

Canned light tuna, which is typically made from smaller, younger skipjack, contains the lowest levels of mercury among common tuna varieties.

Yes, many other fish are excellent sources of omega-3 fatty acids with lower mercury levels. Good choices include salmon, sardines, and cod.

Yes, their developing brains and nervous systems are more vulnerable to mercury's toxic effects, making it crucial for them to follow specific, more stringent guidelines for seafood consumption.

No, mercury accumulates in the flesh of the fish and cannot be removed through cooking, canning, or other preparation methods.