Is Unagi Healthy to Eat? Unpacking the Nutritional Facts and Risks

December 16, 2025 •

4 min read

Packed with high-quality protein and omega-3 fatty acids, unagi (freshwater eel) is a staple in Japanese cuisine, often revered for its health benefits. While a delicacy, many wonder if this grilled fish is a truly healthy choice or if there are potential downsides to consider.

Quick Summary

Unagi is a nutrient-dense fish rich in omega-3s, protein, and essential vitamins like A, D, and B vitamins, offering significant health benefits. However, it must be cooked thoroughly to neutralize toxins in its blood, and moderation is key due to potential contaminants and the high-calorie sauce used in preparation.

Key Points

Rich in Omega-3s: Unagi is an excellent source of omega-3 fatty acids, which are crucial for heart and brain health and can help reduce inflammation.
Packed with Protein and Vitamins: Eel provides high-quality protein for tissue repair and is loaded with vitamins A, D, and various B vitamins for immunity and energy.
Must Be Cooked: Raw freshwater eel blood contains a dangerous toxin. All unagi must be thoroughly cooked to be safe for consumption.
Lower Mercury, but Moderation is Key: Unagi is relatively lower in mercury than some other predatory fish, but consumption should still be moderate, especially for pregnant women.
Be Mindful of the Sauce: The traditional tare sauce used on unagi is high in sugar and sodium, adding to the calorie count. Consider ordering shirayaki or using less sauce.

Unagi's Impressive Nutritional Profile

Unagi, or freshwater eel, is celebrated for its rich flavor and robust nutritional content. It's a powerhouse of essential nutrients that support various bodily functions. The delicate flesh of unagi is a fantastic source of high-quality protein, which is vital for building and repairing tissues throughout the body.

Omega-3 Fatty Acids

One of the most notable benefits of unagi is its exceptionally high concentration of omega-3 fatty acids, including EPA and DHA. In fact, some sources suggest unagi contains three times the omega-3s as salmon. These healthy fats are crucial for heart health, reducing inflammation, and lowering cholesterol and blood pressure. The DHA content also supports brain function and cognitive health.

Abundant in Vitamins

Unagi is loaded with essential vitamins that play key roles in maintaining overall health. It is particularly rich in:

Vitamin A: Important for vision, immune function, and maintaining healthy skin.
Vitamin D: Helps strengthen bones and improves calcium absorption.
Vitamin E: A potent antioxidant that protects cells from damage.
B Vitamins (B1, B2, B12): Crucial for energy metabolism, nervous system health, and reducing fatigue.

Mineral Content

Beyond vitamins, unagi provides a wealth of minerals necessary for health:

Calcium: Supports strong bones and teeth.
Phosphorus: Works with calcium to support skeletal health.
Iron: Necessary for hemoglobin production and preventing anemia.
Zinc: Supports the immune system and cell growth.

A Comparative Look: Unagi vs. Salmon

To better understand unagi's nutritional value, it's helpful to compare it to another popular, health-forward fish like salmon. While both are excellent sources of omega-3s and protein, they differ in other key areas.


Nutrient (per 100g)	Unagi (Approx.)	Salmon (Varies)	Notes
Calories	~255 kcal	~206 kcal	Unagi is fattier and higher in calories.
Fat	~19.3g	~13g	Unagi has more fat, but it's largely unsaturated.
Protein	~18-19g	~22g	Both are high, with salmon often slightly higher.
Omega-3s (EPA/DHA)	Very High	High	Unagi may contain up to 3x more than salmon.
Vitamin A	Exceptionally High	Lower	Unagi is a better source for Vitamin A.
Zinc	5x higher	Lower	Unagi has significantly more zinc.
Vitamin B1, B2, B6	Lower	Higher	Salmon is richer in several B vitamins.

Important Risks and Safety Precautions

While the nutritional benefits are clear, it's crucial to be aware of the safety concerns associated with unagi.

The Danger of Raw Eel

Raw freshwater eel is poisonous and should never be consumed. The blood of freshwater eel contains a potent neurotoxin that can cause muscle cramping and harm to the nervous system. This toxin is completely neutralized when cooked at temperatures above 167°F (75°C), making thoroughly cooked unagi safe to eat. For this reason, all unagi served in restaurants, including in sushi, has been cooked.

Mercury and Contaminants

Although unagi is generally considered to be lower in mercury than large predatory fish like tuna, it's still a concern, especially for pregnant women. The FDA recommends that pregnant women limit their intake of fish to 12 ounces per week and that eel be consumed in moderation due to its mercury content. Additionally, depending on its source, eel can be exposed to environmental toxins and parasites. Sourcing from a reputable and knowledgeable vendor is key to mitigating these risks.

The Role of "Tare" Sauce

In Japanese cuisine, unagi is often prepared with a sweet, soy-based sauce called tare. While delicious, this sauce can be high in sugar and sodium, which can add unnecessary calories and compromise the overall healthiness of the dish, especially when consumed frequently or in large amounts.

Choosing and Preparing Unagi Safely

To ensure a healthy and safe experience with unagi:

Always Eat It Cooked: As mentioned, consuming raw eel is dangerous. Ensure any unagi you eat is properly cooked.
Buy from a Trusted Source: Look for unagi from reputable restaurants or suppliers who can confirm its origin and processing standards. Most unagi sold today is farm-raised, which can offer better control over quality.
Mind the Sauce: When eating unagi don or kabayaki, be mindful of the amount of tare sauce used. You can request a lighter application of sauce or opt for shirayaki style, which is grilled without sauce, allowing the natural flavor of the eel to shine.
Check for Bones: While expertly deboned, tiny bones can occasionally remain. Exercise caution, especially when serving children.

Conclusion

Unagi is a highly nutritious food, packed with heart-healthy omega-3s, high-quality protein, and a range of vital vitamins and minerals. It can be a healthy addition to a balanced diet when enjoyed in moderation. The key to safely enjoying unagi lies in ensuring it is always thoroughly cooked to neutralize its natural toxins and being mindful of the sugary sauces often used in its preparation. By following proper safety precautions, you can savor this Japanese delicacy while reaping its many health benefits.

Authoritative External Link: Environmental Working Group - Seafood Guide

Frequently Asked Questions

Unagi is considered a fish to be eaten in moderation during pregnancy due to its moderate mercury content. However, cooked eel is generally considered safe if limited. Always consult a healthcare provider for personalized advice.

Unagi has a relatively low mercury content compared to larger, higher-chain-of-command fish like tuna. However, moderation is still recommended, and pregnant women should be cautious.

Raw freshwater eel contains a protein toxin in its blood that is harmful to humans. This toxin is destroyed by cooking, which is why all eel served in restaurants is thoroughly cooked.

Unagi is freshwater eel, while anago is saltwater eel. Anago is typically lighter in flavor and has a lower fat content than unagi. Both are served cooked in Japanese cuisine.

Unagi is rich in omega-3 fatty acids for heart and brain health, high in protein, and a good source of vitamins A, D, and B vitamins. It also provides essential minerals like calcium and iron.

While unagi itself is nutrient-dense, the traditional preparation with sweet, soy-based tare sauce can be high in calories and sugar. Consuming it in moderation and being mindful of the sauce is important for managing weight.

It is best to purchase unagi from a reputable Japanese restaurant or a specialty food store that can confirm the source. Frozen, pre-cooked unagi from a trusted supplier is also a safe option.