Skip to content
Ntro

What are the side effects of canned tuna?

•
7 min read

According to Consumer Reports, about a third of Americans eat canned tuna at least twice a month, but frequent consumption necessitates an understanding of the potential side effects of canned tuna, such as mercury and sodium intake. While a convenient and affordable source of protein and omega-3s, its regular consumption isn't without risks.

Quick Summary

Canned tuna consumption can lead to side effects like mercury poisoning, histamine-induced reactions from improper storage, and issues related to high sodium content. The risk profile depends on the type of tuna and frequency of intake.

Key Points

  • Moderate consumption is essential: Due to the potential for mercury buildup, canned tuna should be consumed in moderation, not daily.

  • Albacore has higher mercury than light tuna: The mercury content in tuna varies by species; choose canned light (skipjack) tuna over albacore for lower mercury intake.

  • Vulnerable groups must limit intake: Pregnant women, breastfeeding mothers, and young children should follow specific guidelines to limit their mercury exposure from tuna.

  • Histamine poisoning is a risk: Improper handling before canning can cause scombroid poisoning, and the resulting histamine is not destroyed by cooking.

  • Watch for high sodium: Many canned tuna products contain high levels of sodium, which can increase blood pressure. Choose low-sodium versions or rinse the tuna to reduce salt.

  • Be aware of can linings: Some tuna cans may contain BPA, a chemical with debated health effects. Some brands offer BPA-free options.

  • Vary protein sources: To minimize any potential risks and ensure a balanced diet, it's wise to include other protein sources in your meals besides canned tuna.

In This Article

Canned tuna is a pantry staple prized for its convenience, affordability, and high protein content. It is also a good source of heart-healthy omega-3 fatty acids. However, consumers should be aware of the potential health risks, which include mercury contamination, histamine poisoning, and high sodium levels. By understanding these factors and practicing moderation, you can continue to enjoy canned tuna as part of a balanced diet.

Understanding the Primary Risks

There are three main health concerns associated with canned tuna consumption: mercury, histamine, and sodium. Each of these can have different effects on the body, depending on the type of tuna consumed, preparation, and individual sensitivity.

Mercury Toxicity

Mercury is a naturally occurring heavy metal that enters oceans through pollution and natural events. Bacteria in the water convert it into methylmercury, which is absorbed by fish and accumulates up the food chain. As a predatory species, tuna can accumulate significant amounts of mercury, especially larger, longer-living varieties. The effects of chronic mercury exposure can be severe, primarily targeting the nervous system. The U.S. Environmental Protection Agency (EPA) notes that most people have low blood mercury levels, but excessive exposure can cause adverse effects.

Symptoms of mercury poisoning include:

  • Memory loss and concentration problems
  • Irritability, anxiety, and mood swings
  • Numbness or tingling sensations in the hands and feet
  • Muscle weakness or coordination issues
  • Hearing or vision changes
  • In severe cases, neurological damage can be permanent

Histamine (Scombroid) Poisoning

Scombroid poisoning is a foodborne illness caused by eating fish that contains high levels of histamine due to improper storage. If fish is not refrigerated or chilled properly, naturally occurring bacteria can multiply and convert histidine (an amino acid) into histamine. Because histamine is heat-stable, cooking or canning does not destroy it. The symptoms resemble an allergic reaction and can appear within minutes to a few hours after eating.

Symptoms of scombroid poisoning can include:

  • Facial flushing or rash
  • A peppery or metallic taste in the mouth
  • Headaches and dizziness
  • Nausea, vomiting, and diarrhea
  • Tingling or burning sensations in the mouth
  • Heart palpitations

High Sodium Levels

Like many other canned and processed foods, canned tuna can be high in sodium due to the preservation process. A high-sodium diet is a known risk factor for high blood pressure (hypertension), which can contribute to heart disease and stroke. Consumers should be mindful of their sodium intake, especially if they have pre-existing health conditions or are sensitive to sodium.

Ways to manage sodium intake from canned tuna include:

  • Choosing "no salt added" or "low sodium" varieties.
  • Rinsing the tuna in a strainer before eating.
  • Pairing it with fresh vegetables or other low-sodium ingredients.

Other Considerations: Can Linings and Additives

Some cans are lined with a chemical called bisphenol A (BPA) to prevent corrosion, and there is a long-standing debate about the health effects of regular exposure. While many manufacturers have moved to BPA-free linings, it is a point of consideration for some consumers. The nutritional content can also vary based on whether the tuna is packed in oil or water; water-packed tuna is generally lower in fat and calories.

Comparison of Tuna Types

The species of tuna significantly affects its mercury content and nutritional profile. Here’s a comparison of the most common varieties found in cans.

Feature Albacore Tuna (White) Light/Skipjack Tuna
Mercury Content Higher Lower
Omega-3 Fats Higher Lower
Fat & Calories Higher when packed in oil Lower
Recommended Intake Limit, especially for vulnerable groups like pregnant women and children Can be eaten more frequently (in moderation)

Guidelines for Safer Canned Tuna Consumption

To minimize potential side effects, it's wise to follow these guidelines:

  • Choose Wisely: Opt for canned light tuna (typically skipjack), which has a lower mercury content than canned albacore.
  • Limit Frequency: Stick to recommended weekly consumption guidelines, especially if you are pregnant, breastfeeding, or feeding young children.
  • Read Labels: For those concerned about blood pressure, select “no salt added” or “low sodium” varieties.
  • Vary Your Protein Sources: Don’t rely solely on canned tuna for your protein intake. Incorporate other sources like salmon, chicken, or plant-based proteins.
  • Rinse and Prepare Properly: Rinsing the tuna can reduce the sodium content, and always ensure proper refrigeration after opening to prevent bacterial growth.
  • Check Canning Material: If concerned about BPA exposure, choose brands that advertise BPA-free can linings.

Conclusion

While canned tuna offers a convenient and nutrient-rich food option, being mindful of its potential side effects is essential for maintaining optimal health. By prioritizing lower-mercury varieties like light or skipjack tuna, controlling sodium intake, and following proper food safety practices, you can mitigate the associated risks. Ultimately, moderate consumption and dietary variety are key to safely enjoying canned tuna as a regular part of a healthy diet.

For more detailed information on tuna and mercury levels, consult the U.S. Food and Drug Administration's guidelines.

Key Takeaways

  • Mercury is a Key Concern: Tuna contains mercury, with larger fish like albacore having more than smaller skipjack or light tuna.
  • Vulnerable Populations Need Caution: Pregnant women, breastfeeding mothers, and young children should adhere to specific, lower consumption limits due to mercury's neurotoxic effects.
  • Scombroid Poisoning Risk Exists: Improper refrigeration can cause histamine to form in tuna, leading to an allergic-like reaction that is not destroyed by canning.
  • Sodium Content Varies: Canned tuna can be high in sodium; check labels for “no salt added” or “low sodium” versions and consider rinsing to reduce salt.
  • Moderation is Prudent: Regular, heavy consumption is not recommended; a varied diet with other protein sources helps balance intake and minimize risks.
  • BPA Exposure is Possible: Some can linings may contain BPA, a chemical with debated health impacts, though many brands offer BPA-free options.

FAQs

Q: How much canned tuna is safe to eat? A: The recommended intake depends on the type of tuna and your health status. Healthy adults can generally eat 2-3 servings of canned light tuna per week, while pregnant women and children have stricter limits. Limit albacore to one serving per week.

Q: What are the symptoms of mercury poisoning from canned tuna? A: Symptoms of chronic mercury exposure include memory loss, irritability, tingling sensations, muscle weakness, and impaired speech or vision. Effects are more pronounced with high, regular consumption.

Q: Can histamine poisoning occur from canned tuna? A: Yes. If the fish was improperly handled and refrigerated before being canned, bacteria could produce histamine. The histamine remains even after canning, and cooking does not destroy it.

Q: Is there a difference in mercury between albacore and light canned tuna? A: Yes, canned albacore (or white) tuna generally has a higher mercury content than canned light tuna (usually skipjack) because albacore are larger, older fish.

Q: What are the symptoms of histamine (scombroid) poisoning? A: Scombroid poisoning symptoms can include a rash, facial flushing, headache, dizziness, and a metallic or peppery taste in the mouth. They typically appear shortly after consumption.

Q: Are low-sodium versions of canned tuna available? A: Yes, most brands offer varieties labeled as “low sodium” or “no salt added.” You can also reduce sodium by rinsing regular canned tuna under running water.

Q: Should pregnant women avoid canned tuna completely? A: No, they don't have to. The FDA recommends pregnant women eat 2-3 servings of canned light tuna (low mercury) per week, but limit higher-mercury albacore to one serving per week. Consulting a doctor is recommended.

Citations

Frequently Asked Questions

The primary health risk is mercury contamination, specifically methylmercury. As a large predatory fish, tuna can accumulate significant amounts of mercury, which can pose a risk, especially with frequent consumption, and is most concerning for vulnerable populations.

Canned light tuna, which is typically made from smaller skipjack tuna, has lower mercury levels than canned albacore (white) tuna. This is because smaller, younger fish have had less time to accumulate the heavy metal.

Scombroid poisoning is a foodborne illness caused by high levels of histamine in fish due to improper refrigeration. Yes, it can occur from canned tuna if the fish was spoiled before the canning process, as canning does not destroy histamine.

You can reduce the sodium content by choosing cans labeled 'no salt added' or 'low sodium.' For regular canned tuna, rinsing it thoroughly in a strainer can also help wash away some of the excess salt.

Yes. Tuna packed in oil is higher in fat and calories, while tuna packed in water is leaner. Additionally, some sources suggest water-packed tuna may be higher in the beneficial omega-3 fatty acid DHA.

The FDA recommends that pregnant women eat 2-3 servings per week of canned light tuna and limit higher-mercury albacore to just one serving per week. Bigeye tuna should be avoided.

Neurological symptoms of mercury poisoning include memory loss, cognitive difficulties, anxiety, irritability, numbness or tingling in the extremities, muscle weakness, and impaired coordination or speech.

References

  1. 1
    Is Canned Tuna Healthy? Nutrition, Benefits, and Downsides
  2. 2
    Tuna: Benefits, Nutrition, and Risks
  3. 3
    Can I Eat Canned Tuna Every Day?
  4. 4
    How Worried Should You Be About Mercury in Your Tuna?
  5. 5
    Mercury Poisoning: Causes, Symptoms, Treatment, and More
  6. 6
    Health Effects of Exposures to Mercury | US EPA
  7. 7
    Fish histamine poisoning | NSW Food Authority
  8. 8
    What Happens to Your Body When You Eat Tuna Regularly
  9. 9
    How to Reduce Salt Wash in a Tuna Can : Happy, Healthy & Fit - YouTube
  10. 10
    Is It Healthy To Eat Canned Tuna Every Day? Dietitians Explain

Related Topics:

#side effects #Sodium intake #dietary recommendations #canned tuna #seafood safety #BPA #histamine #mercury poisoning

Medical Disclaimer

This content is for informational purposes only and should not replace professional medical advice.