What Does Raw Tuna Do to Your Body? The Health Impact Explained

January 4, 2026 •

4 min read

According to the FDA, certain types of tuna are exempt from freezing requirements for raw consumption due to low documented parasitic infection rates. Raw tuna is a popular food, particularly in sushi and sashimi, but its effects on the human body involve both nutritional advantages and potential health risks that are important to understand.

Quick Summary

Raw tuna provides high-quality protein, heart-healthy omega-3 fatty acids, and essential vitamins and minerals, supporting muscle repair, brain function, and cardiovascular health. However, potential risks include exposure to parasites and high levels of mercury, particularly in larger species. Proper sourcing and moderation are critical for safe consumption.

Key Points

Rich in Omega-3s: Raw tuna contains high levels of omega-3 fatty acids (EPA and DHA), which support heart health, reduce inflammation, and enhance cognitive function.
Excellent Protein Source: It provides a high-quality, lean protein essential for muscle repair, growth, and weight management.
Potential for Parasites: Consuming raw tuna carries a risk of parasitic infection, which can be mitigated by proper commercial freezing techniques.
Mercury Levels: Larger tuna species (bluefin, bigeye) contain higher levels of mercury, a neurotoxin, requiring moderate consumption to avoid accumulation over time.
Food Safety is Paramount: To avoid bacterial contamination like Salmonella, raw tuna must be sourced from reputable suppliers who follow strict handling and freezing protocols.
Nutrient Retention: Eating tuna raw can preserve a higher concentration of heat-sensitive nutrients like omega-3s and vitamin D compared to cooked tuna.

Nutritional Benefits: The Positive Impact of Raw Tuna

Raw tuna, especially high-grade sashimi varieties like yellowfin and bluefin, offers a dense profile of beneficial nutrients that can profoundly impact your body. Unlike cooking, consuming tuna raw can preserve the integrity of some of these delicate nutrients, maximizing their health advantages.

Protein Power for Muscle and Repair

Tuna is an exceptional source of high-quality, lean protein, crucial for building and repairing tissues, including muscle fibers. A typical 3-ounce serving of albacore tuna contains approximately 13 grams of protein. This makes it an excellent post-workout option for athletes and a key component of a weight-loss diet, as protein promotes satiety and helps maintain lean muscle mass.

Heart and Brain Health from Omega-3 Fatty Acids

The fats in tuna are predominantly healthy, polyunsaturated fats, specifically omega-3 fatty acids (EPA and DHA). These essential fats are vital for:

Reducing levels of 'bad' LDL cholesterol and triglycerides, which lowers the risk of cardiovascular disease.
Improving brain cell structure and function, which supports cognitive health and may help prevent age-related decline.
Reducing overall body inflammation, which is linked to many chronic diseases, including heart disease and some cancers.
Supporting eye health by benefiting the retina and reducing the risk of dry eye syndrome.

A Rich Source of Vitamins and Minerals

Raw tuna is a treasure trove of essential micronutrients that are critical for various bodily functions. It's notably rich in Vitamin B12, which is essential for DNA synthesis and preventing anemia. Other important nutrients include:

Vitamin D: Crucial for bone health and immune system function.
Selenium: An antioxidant that protects the body from cellular damage.
Potassium: Important for maintaining healthy blood pressure.
Iron: Necessary for red blood cell formation and preventing anemia.

Potential Risks: The Downsides of Eating Raw Tuna

While the nutritional benefits are clear, eating raw tuna is not without risks. These concerns are primarily related to foodborne illness and the accumulation of heavy metals.

Parasites

One of the main dangers of consuming raw fish is the potential for parasitic infection. Tuna, especially wild-caught varieties, can harbor parasites like Anisakidae, which can cause gastrointestinal symptoms such as diarrhea, vomiting, and abdominal pain. Reputable restaurants and fishmongers mitigate this risk by freezing the fish according to FDA guidelines, which kills most parasites. However, the risk is not entirely eliminated, especially when sourcing from less controlled environments.

Mercury Contamination

As a predatory fish high on the food chain, tuna accumulates methylmercury, a neurotoxin. Larger species like bluefin and bigeye tend to have higher concentrations than smaller species like skipjack and yellowfin. Excessive mercury accumulation over time can lead to serious health problems, including brain and heart damage. Therefore, moderation is key, and vulnerable populations like pregnant women, children, and those with weakened immune systems should be especially cautious.

Bacterial and Scombrotoxin Poisoning

Raw tuna can be a vector for bacterial contamination, such as Salmonella, if not handled and stored properly. Additionally, if certain fish like tuna are temperature-abused (not kept cold enough), bacteria can produce scombrotoxin, which causes an allergic-like reaction with symptoms such as flushing, headaches, and a peppery taste in the mouth. This is another reason proper handling and a reliable source are crucial.

Raw vs. Cooked Tuna: A Nutritional Comparison

There are key nutritional differences between eating tuna raw and cooked, which can influence which form is best for your diet.


Feature	Raw Tuna	Cooked Tuna
Omega-3s	Higher levels, as cooking can cause a 15-20% reduction.	Slightly lower due to heat, but still a good source.
Protein	Slightly higher bioavailability (90-92%).	Slightly lower bioavailability (85-87%) but potentially more digestible for some.
Vitamins	Better retention of fat-soluble vitamins like D, as heat can degrade them.	Vitamin D levels can decrease with cooking.
Contaminants	Risk of parasitic and bacterial infection if not handled correctly.	Cooking eliminates parasites and bacteria, but high heat can produce carcinogenic compounds called HCAs.
Mercury	Present in both forms, concentration depends on the species.	Present in both forms, concentration depends on the species.

Making an Informed Choice

To safely enjoy raw tuna, always purchase from a reputable source that follows proper food safety guidelines, such as commercial freezing. Consume raw tuna in moderation and choose species lower in mercury when possible. For those concerned about risks, cooking tuna completely eliminates parasites and bacteria, though it may slightly alter the nutritional profile.

In conclusion, raw tuna provides powerful nutritional benefits, especially for heart and brain health, but it's essential to be mindful of the associated risks. By making informed choices about sourcing and consumption frequency, you can enjoy this versatile fish as part of a healthy diet. For more detailed information on food safety regulations for raw fish, the FDA's official guidelines are an excellent resource.

Frequently Asked Questions

Yes, eating raw tuna in moderation can be beneficial due to its high content of omega-3 fatty acids, lean protein, and essential vitamins and minerals, which support heart, brain, and overall health.

The main risks include parasitic infection (Anisakis worms), bacterial contamination (Salmonella), and mercury poisoning, especially from larger tuna species. These risks can be managed by sourcing high-quality, properly frozen fish and consuming it in moderation.

Pregnant and breastfeeding women, children, the elderly, and individuals with compromised immune systems should avoid raw tuna due to a higher risk of foodborne illness and mercury exposure.

Raw tuna generally has slightly higher levels of omega-3 fatty acids, as the cooking process can cause a minor reduction (around 15-20%).

The term 'sushi-grade' is a marketing term and not an official certification. It indicates that the seller deems the fish safe for raw consumption, often because it has been handled and frozen according to FDA guidelines.

To minimize mercury risk, limit your consumption frequency and choose smaller tuna species like skipjack or yellowfin over larger ones like bluefin or bigeye. Also, ensure you consume a variety of other low-mercury fish.

Yes, it is possible to get food poisoning from raw tuna due to bacterial contamination or parasites. To minimize this risk, always obtain your tuna from a trusted, hygienic source that handles and stores fish correctly.