How safe is mackerel to eat?

While praised for its high omega-3 content, some species of mackerel, particularly King mackerel, contain higher levels of mercury. So, how safe is mackerel to eat? Its safety profile depends heavily on which species you choose and how it is handled.

Quick Summary

Mackerel is a healthy oily fish, but safety hinges on the specific species due to varying mercury concentrations. Smaller, fast-growing varieties like Atlantic mackerel are safe for regular consumption, while larger King mackerel should be limited, especially for vulnerable groups. Proper handling and storage are crucial to prevent histamine poisoning.

Key Points

• Choose Low-Mercury Species: Opt for smaller, short-lived fish like Atlantic mackerel over larger, predatory King mackerel to minimize mercury exposure.

• Prevent Scombroid Poisoning: Ensure mackerel is refrigerated promptly after being caught, as histamines that cause poisoning are not destroyed by cooking.

• Vulnerable Groups Must Avoid High-Mercury Fish: Pregnant women, nursing mothers, and young children should completely avoid King mackerel and limit other high-mercury seafood.

• Enjoy Nutritional Benefits Safely: Mackerel is rich in Omega-3s, protein, and vitamins, and these benefits can be safely enjoyed by following consumption guidelines.

• Consider Canned Options Wisely: Canned mackerel retains nutritional value but can be high in sodium; check labels and choose low-sodium options.

• Look for Signs of Freshness: When buying fresh mackerel, look for clear, bright eyes and firm flesh with a mild ocean smell.

• Vary Your Fish Intake: Diversifying your seafood choices reduces exposure to potential contaminants from any single source.

Mackerel Safety: Understanding Mercury Content

The most significant concern regarding the safety of eating mackerel is its mercury content. Mercury is a neurotoxin that can accumulate in fish, with larger, longer-lived predatory fish typically having the highest levels. Mackerel is a broad term for multiple species, and their mercury levels vary dramatically based on size, lifespan, and position in the food chain.

The Mercury Contrast: Atlantic vs. King Mackerel

• Atlantic Mackerel (Scomber scombrus): Considered a "best choice" by the FDA, this smaller, faster-growing species has very low mercury levels. It primarily feeds on plankton, which keeps its mercury bioaccumulation minimal. Atlantic mackerel is a safe, nutritious option for most people, including pregnant women and children, when consumed in moderation, typically 2–3 servings per week.
• King Mackerel (Scomberomorus cavalla): In contrast, King mackerel is a larger, longer-lived predator with significantly higher mercury levels. The FDA recommends that pregnant women, nursing mothers, and young children avoid King mackerel entirely due to these high concentrations.
• Spanish Mackerel (Scomber maculatus): This species falls somewhere in the middle, with a moderate mercury level. Its consumption should be limited, especially for vulnerable populations.

The Threat of Scombroid Poisoning

Beyond mercury, another critical safety issue with mackerel and other Scombridae family fish is scombroid poisoning, or histamine fish poisoning. This is not a contamination issue but rather a result of improper handling and storage. If fish are not properly chilled after being caught, bacteria on the fish can convert histidine (a natural amino acid in the muscle tissue) into histamine.

How to Prevent Scombroid Poisoning

• Immediate and Continuous Refrigeration: Mackerel must be kept at 0°C (32°F) or below from the moment it is caught until it is cooked or canned.
• Recognize Spoilage Signs: While many contaminated fish may look and smell normal, some develop a “honey-combed” appearance or a sharp, peppery, or metallic taste. Any spoiled fish should be discarded.
• Note that Cooking Does Not Help: Histamines are heat-stable, so cooking, canning, or freezing the fish will not destroy the toxin once it has formed.

Comparison of Mackerel Species

Feature	Atlantic Mackerel	Spanish Mackerel	King Mackerel
Mercury Level	Low	Moderate	High (Avoid for vulnerable groups)
Typical Size	Small (up to 400g)	Medium	Large (up to 5 feet)
Diet	Plankton, smaller fish	Smaller fish	Larger predatory fish
Safety for Vulnerable Groups	Best Choice	Limit Consumption	Should Avoid
FDA/EPA Rating	Best Choice	Good Alternative	Should Avoid

The Nutritional Benefits of Mackerel

Despite the risks associated with certain species and poor handling, mackerel is a nutritional powerhouse when safely sourced and prepared. Its health benefits are numerous and widely recognized.

Rich in Omega-3 Fatty Acids: Mackerel is one of the best dietary sources of heart-healthy omega-3s, specifically EPA and DHA. These fats are linked to reduced risk of heart disease, lower blood pressure, and enhanced brain function.

Excellent Source of Protein: With approximately 19–21 grams of high-quality, complete protein per 100g serving, mackerel supports muscle growth, satiety, and overall body function.

Packed with Vitamins and Minerals: It provides high levels of Vitamin B12, essential for nerve function and red blood cell production, and Vitamin D, crucial for bone health. It is also a good source of selenium, a powerful antioxidant.

Fresh vs. Canned Mackerel

The choice between fresh and canned mackerel comes down to convenience and sodium content, not nutrition or safety (assuming proper canning procedures). Canned mackerel retains its omega-3 fatty acids, protein, and other nutrients.

• Convenience and Shelf-Life: Canned mackerel offers a long shelf-life and is ready to eat, making it a convenient pantry staple.
• Sodium Consideration: Canned versions, especially those packed in brine or salted, can be high in sodium. Individuals monitoring their sodium intake should opt for low-sodium or unsalted varieties.
• Proper Canning: When purchasing canned mackerel, ensure the cans are not dented, bulging, or leaking to prevent contamination.

Conclusion: Making a Safe and Healthy Choice

Is mackerel safe to eat? Yes, provided you make informed choices. By selecting smaller, low-mercury species like Atlantic mackerel, you can safely enjoy the significant nutritional benefits this oily fish offers. For vulnerable populations like pregnant women and young children, avoiding King mackerel is essential. Always ensure mackerel is handled and stored correctly to prevent scombroid poisoning, regardless of the variety. By following these simple guidelines, you can confidently add this healthy and delicious fish to your diet.

Learn more about safe fish consumption guidelines from the FDA: FDA Advice About Eating Fish

How to Safely Consume Mackerel

• Choose Wisely: Opt for smaller, faster-growing species like Atlantic mackerel to minimize mercury exposure.
• Store Immediately: Ensure fresh mackerel is refrigerated or frozen as soon as possible after purchase to prevent bacterial growth and histamine buildup.
• Check Freshness: Look for bright, clear eyes, firm flesh, and a mild sea scent in fresh mackerel.
• Cook Thoroughly: While cooking doesn't destroy histamine, it kills parasites and bacteria. Always cook mackerel fully unless it is sushi-grade.
• Moderate Canned Intake: Choose low-sodium canned mackerel and eat it in moderation as part of a varied diet to avoid excessive salt.

Navigating Mackerel Choices

• Species Identification: Be aware of the species of mackerel you are buying to understand its mercury risk profile.
• Vary Your Fish: Don't rely solely on mackerel for your fish intake. Incorporate a variety of low-mercury fish to balance nutrients and minimize contaminant exposure.
• Purchase from Reputable Sources: Buy fresh or canned mackerel from trusted suppliers who follow proper handling and processing standards.

Health Benefits at a Glance

• Heart Health: The high omega-3 content helps lower blood pressure and reduce the risk of heart disease.
• Brain Function: Omega-3s contribute to cognitive health and may help protect against neurodegenerative diseases.
• Bone Strength: A rich source of Vitamin D and calcium, mackerel supports strong bones and teeth.
• Immunity Boost: Selenium and vitamins bolster the immune system and protect against oxidative stress.
• Weight Management: The high protein and healthy fats in mackerel help increase satiety.

Choosing the Right Type for You

• Risk Profile: Consider your personal health needs, especially if you are pregnant, nursing, or have a pre-existing condition, before choosing a mackerel species.
• Preparation Method: The preparation of mackerel can influence its health profile, especially with added ingredients like salt or oil.
• Cooking Temperature: Ensure mackerel is cooked to the proper internal temperature to kill any potential bacteria or parasites.

Frequently Asked Questions

Which type of mackerel has the least mercury?

Atlantic mackerel is considered the 'best choice' by health authorities and has very low levels of mercury. Other small, fast-growing species also tend to have lower levels.

Is mackerel safe to eat during pregnancy?

Yes, but with important distinctions. Atlantic mackerel is safe and recommended in moderation (up to two servings a week) for its omega-3s, while King mackerel should be completely avoided due to high mercury levels.

What is scombroid poisoning, and how is it prevented?

Scombroid poisoning is caused by high levels of histamine resulting from bacterial growth in improperly refrigerated fish. To prevent it, ensure mackerel is kept consistently cold from catch to consumption, as cooking does not eliminate the toxin.

Can you get scombroid poisoning from canned mackerel?

Yes, although it's uncommon with properly canned products. If the fish was temperature-abused before canning, the heat-stable histamine can still be present. Always buy from reputable brands and discard any cans that are damaged.

Is canned mackerel as healthy as fresh mackerel?

Canned mackerel retains the majority of the nutrients found in fresh fish, including beneficial omega-3s and protein. The primary nutritional difference is often a higher sodium content in canned versions due to added salt.

How can I tell if fresh mackerel is safe to eat?

Look for a mild ocean scent, clear and bright eyes, and firm flesh that bounces back when pressed. Avoid any fish with a strong, 'fishy' odor or discolored, soft, or wrinkled flesh.

How much mackerel is safe to eat weekly?

For low-mercury species like Atlantic mackerel, up to two or three servings per week is generally considered safe for most adults, including pregnant women. Vulnerable groups should avoid high-mercury species entirely.

What are the health benefits of eating mackerel?

Mackerel is an excellent source of omega-3 fatty acids, high-quality protein, vitamin B12, vitamin D, and selenium, which support heart health, brain function, and immune health.