What are the side effects of eating tuna fish?

December 27, 2025 •

3 min read

According to health experts, tuna can contain high levels of mercury, a neurotoxin that accumulates over time. This makes understanding what are the side effects of eating tuna fish crucial for frequent consumers and sensitive populations to make informed decisions about their dietary choices.

Quick Summary

The consumption of tuna poses risks primarily from mercury buildup, particularly with frequent intake of larger, higher-mercury species like albacore. Following recommended serving sizes and opting for lower-mercury types, such as canned light tuna, can help mitigate these potential health concerns.

Key Points

Mercury Exposure: Tuna contains methylmercury, a neurotoxin that bioaccumulates in the body and poses health risks, especially with high consumption.
Neurological Symptoms: Chronic mercury poisoning from excessive tuna intake can cause neurological issues like memory loss, tremors, anxiety, and depression.
Vulnerable Populations: Pregnant women, breastfeeding mothers, and young children are particularly susceptible to mercury's effects on brain development and should follow stricter consumption guidelines.
Albacore vs. Light Tuna: Albacore (white) tuna has significantly higher mercury levels than canned light (skipjack) tuna, requiring more limited consumption.
Moderation is Key: Experts recommend consuming tuna in moderation, typically limiting intake to 1-3 servings per week depending on the species and individual health status.
Other Risks: Besides mercury, potential side effects can include high sodium intake from some canned products and exposure to industrial chemicals like BPA from can linings.

The Primary Concern: Mercury Accumulation

The most significant and well-documented side effect associated with consuming tuna is the risk of mercury exposure, specifically methylmercury. Methylmercury is a neurotoxin that enters the marine food chain through environmental pollution, such as from burning fossil fuels. As a predatory fish, tuna consumes smaller fish, leading to a process known as bioaccumulation, where mercury concentrations increase further up the food chain. When humans consume tuna, this methylmercury is absorbed by the body, where it can accumulate in the brain, nervous system, and kidneys.

For most healthy adults, consuming tuna within recommended guidelines poses a low risk. However, prolonged, high-level exposure can lead to chronic mercury poisoning with serious health consequences. Symptoms can range from mild neurological issues to severe impairment and can affect individuals differently.

Potential Health Effects of Mercury Exposure

Neurological Damage: Mercury acts as a neurotoxin, which can lead to a variety of neurological and behavioral disorders. Common symptoms include memory loss, tremors, loss of motor skills, anxiety, and depression.
Developmental Issues: Infants, young children, and fetuses are particularly vulnerable to mercury's effects. Exposure during critical developmental stages can impair brain and nervous system development, potentially leading to learning disabilities, developmental delays, and other cognitive difficulties.
Cardiovascular Risks: Some research suggests a link between mercury buildup and an increased risk of heart disease.
Kidney Problems: Long-term exposure to high levels of mercury can cause damage to the kidneys and affect their function.

Other Potential Side Effects

While mercury is the main concern, several other factors can contribute to potential side effects from eating tuna:

Contaminants in Canned Tuna

BPA Exposure: Some canned tuna products use a lining that contains bisphenol A (BPA), an industrial chemical. Though the effects of low-level exposure are debated, some people choose to avoid it due to concerns about potential health impacts.
Microplastics: Marine environments are increasingly contaminated with microplastics, tiny plastic particles that can accumulate in seafood, including tuna. The long-term health effects of consuming microplastics are still under investigation.

High Sodium Content

Many canned tuna varieties are packed with added salt to enhance flavor and act as a preservative. Consuming a diet high in sodium can contribute to high blood pressure and other cardiovascular issues, especially for individuals with a pre-existing heart condition or those sensitive to salt. Opting for low-sodium or 'no salt added' varieties can help mitigate this risk.

Comparison: Canned Light vs. Albacore Tuna

The species of tuna you consume plays a significant role in your mercury exposure. Here is a comparison of two common types of canned tuna:


Feature	Canned Light Tuna (Skipjack)	Canned Albacore Tuna (White)
Mercury Content	Generally lower due to smaller size and shorter lifespan.	Significantly higher than light tuna.
Texture	Softer, smaller pieces.	Firmer, larger, and more steak-like pieces.
Flavor	Stronger, more robust flavor.	Milder flavor.
FDA/EPA Recommendation	Adults: 2–3 servings per week.	Adults: Limit to 1 serving per week.
Recommendation for Sensitive Groups	Can be consumed by pregnant/breastfeeding women and children in limited amounts.	Should be avoided or strictly limited by pregnant/breastfeeding women and children.

Minimizing the Risks of Tuna Consumption

To enjoy the nutritional benefits of tuna while minimizing potential side effects, consider the following strategies:

Choose Lower-Mercury Species: Prioritize canned light tuna (usually skipjack) over albacore or bigeye varieties.
Moderate Your Intake: Follow the weekly serving recommendations from health organizations like the FDA and EPA. A varied diet including other low-mercury fish like salmon, sardines, and tilapia can also help.
Read Labels: Look for tuna packed in water and with no added salt to control sodium and calorie intake. Some brands also test for mercury and label their products accordingly.
Consider Sustainable Sources: The method of fishing can sometimes impact mercury levels. Choosing sustainable, pole-and-line-caught options can be a more environmentally conscious choice.
Stay Informed: For the latest guidelines on mercury in seafood, refer to the FDA website for reliable information.

Conclusion: Balancing Benefits and Risks

While tuna is a nutrient-dense food rich in protein and omega-3 fatty acids, it is not without potential side effects, with mercury accumulation being the most significant concern. By understanding the difference between tuna species and their mercury content, adhering to recommended consumption limits, and choosing low-sodium and sustainably sourced options, you can enjoy tuna as part of a healthy, balanced diet. Moderation and variety are key to reaping the benefits while minimizing any potential risks, especially for vulnerable populations such as pregnant women and young children.

Frequently Asked Questions

Yes, it is possible to get mercury poisoning from eating too much tuna, particularly higher-mercury species like albacore, over a prolonged period. This is due to the gradual accumulation of methylmercury in the body.

The amount of tuna that is safe to eat depends on the type. The FDA recommends limiting albacore tuna to one 4-ounce serving per week, while canned light (skipjack) tuna can be consumed two to three times per week for most adults.

Generally, canned light tuna, which comes from smaller species like skipjack, tends to have lower mercury levels than fresh or frozen tuna steaks from larger species like albacore and bigeye. Larger, older fish accumulate more mercury over time.

Initial symptoms of mercury poisoning can include numbness or a tingling sensation in the hands and feet, muscle weakness, memory problems, and changes in mood or vision.

Women who are pregnant, breastfeeding, or planning to become pregnant, as well as young children, should either avoid tuna or stick to very limited servings of lower-mercury light tuna, as mercury can impact development.

No, draining the oil or water from canned tuna does not remove the methylmercury, as it is tightly bound to the fish's protein.

For those concerned about sodium and fat intake, tuna packed in water is a better choice. However, the packing liquid does not affect the mercury content.