Why do some vegetarians eat tuna? Understanding the pescatarian diet

October 7, 2025 •

4 min read

According to a 2025 study on dietary trends, many people adopting more plant-based lifestyles sometimes include seafood as a source of lean protein. This practice is why some people who appear to be vegetarian eat tuna, though they are more accurately following a pescatarian diet.

Quick Summary

Many people who avoid meat but consume tuna are called pescatarians. They adopt this dietary pattern for various health benefits, environmental factors, or ethical considerations, valuing the nutritional profile of fish like omega-3 fatty acids and lean protein.

Key Points

Pescatarianism, not vegetarianism: People who eat tuna but no other meat are called pescatarians, not vegetarians, as their diet includes fish and seafood.
Rich in Omega-3s: A key reason for this diet is the superior access to heart-healthy omega-3 fatty acids (EPA and DHA), which are abundant in fatty fish like tuna.
Nutrient Boost: Tuna provides essential nutrients like high-quality protein, vitamin B12, and vitamin D that can be harder to obtain on a strict vegetarian diet.
Balanced Ethics: Some choose pescatarianism for ethical reasons, believing it's a more acceptable compromise than eating land animals, given perceptions about fish sentience.
Lower Environmental Footprint: This diet can offer a lower ecological impact compared to traditional omnivorous diets, especially when selecting sustainably sourced fish.
A Flexible Transition: For many, pescatarianism serves as a practical, flexible middle ground or a gradual transition toward a fully plant-based lifestyle.

A common point of confusion for those unfamiliar with the nuances of dietary patterns is encountering someone who identifies as a vegetarian but includes tuna in their diet. This dietary choice is not a misunderstanding of vegetarianism but rather a distinct, intentional eating style known as pescatarianism. A pescatarian diet is primarily plant-based but includes fish and seafood, while excluding land animals and poultry. People choose this path for a variety of reasons, blending health goals with ethical and environmental concerns.

Health-related motivations

One of the most significant drivers behind the pescatarian diet is the desire to reap the health benefits of both a plant-based diet and seafood. While a well-planned vegetarian diet can be healthy, incorporating fish offers some unique nutritional advantages that can be challenging to obtain otherwise.

Accessing crucial nutrients

Omega-3 Fatty Acids (EPA and DHA): These are essential fats vital for brain health, heart function, and reducing inflammation. While some plant foods contain the omega-3 ALA, the body's conversion of ALA into the more beneficial EPA and DHA is inefficient. Fatty fish like tuna, salmon, and sardines are rich, direct sources of EPA and DHA.
Vitamin B12: This vitamin, essential for nerve function and red blood cell formation, is almost exclusively found in animal products. Strict vegetarians and vegans must rely on fortified foods or supplements to meet their needs. Including fish naturally provides a reliable source of B12.
High-Quality Protein: Tuna is an excellent source of lean, complete protein, which is crucial for building and repairing muscle tissue. For some, it is a more convenient and appealing source of protein than relying solely on plant-based alternatives.
Vitamin D: Fatty fish and canned tuna are among the few natural food sources of vitamin D, which is important for bone health and immune function.

Potential health outcomes

Studies suggest that pescatarians often enjoy many of the same health benefits as vegetarians, such as a lower risk of obesity, heart disease, and type 2 diabetes, while also benefiting from the nutrients in seafood. Some research even indicates that the longevity boost may be greater for pescatarians than strict vegetarians.

Ethical and environmental considerations

For many, the transition to a pescatarian diet is guided by ethical considerations that differentiate between land animals and fish. This reasoning often centers on perceptions of animal sentience and the environmental impact of food production.

A perceived ethical middle ground

Some pescatarians believe that fish are less complex organisms than mammals and birds, and therefore may not experience pain or suffering in the same way. While this is a complex and highly debated topic within animal welfare, it offers an ethical rationale for those who wish to reduce their contribution to animal suffering without fully committing to vegetarianism. Additionally, many people have a greater emotional connection to land animals like cows and pigs than they do to fish.

A lighter ecological footprint

Concerns over the environmental impact of industrial animal agriculture, including high greenhouse gas emissions, land use, and resource consumption, are often a factor in dietary choices. While commercial fishing is not without its own environmental problems like overfishing and bycatch, the overall ecological footprint of producing fish is generally considered lower than that of red meat and poultry. Choosing sustainably sourced seafood, such as smaller fish or those caught using specific methods, can further reduce this impact.

The path to dietary change

For some, becoming a pescatarian is a stepping stone toward a fully vegetarian or vegan diet. It allows for a gradual reduction in meat consumption without the immediate pressure of eliminating all animal products. This flexibility can make the transition easier and more sustainable in the long run. The diet also provides more options when dining out, which can be a practical advantage for social situations.

Potential drawbacks of the pescatarian diet

Despite the benefits, there are considerations to keep in mind, most notably the risk of contaminants in some fish. Larger, longer-lived fish like tuna can accumulate higher levels of mercury, a neurotoxin. It is important for pescatarians to be mindful of their consumption and choose smaller species or follow advisories, especially if they are pregnant or breastfeeding. Responsible consumption also involves seeking out sustainably sourced seafood to mitigate the environmental impact of fishing.

Comparison of different dietary patterns


Feature	Pescatarian Diet	Vegetarian Diet	Omnivore Diet
Protein Sources	Fish, seafood, plants, optional dairy/eggs	Plants, optional dairy/eggs	Land animals, poultry, fish, plants, dairy, eggs
Omega-3s (EPA/DHA)	Excellent source from fatty fish	Sourced from ALA in plants (inefficient conversion) or supplements	Variable, can be high from fish or meat/eggs
Vitamin B12	Sourced from fish, optional dairy/eggs	Must be supplemented or sourced from fortified foods	Readily available from various animal products
Primary Focus	Plant-based with seafood	Plant-based with optional dairy/eggs	No restrictions, includes all food groups
Dietary Flexibility	High (more options than vegetarian)	Moderate (more restricted than pescatarian)	Very high
Environmental Impact	Generally lower than omnivore, depends on sourcing	Generally lower than pescatarian/omnivore	Often the highest, especially for red meat

Final thoughts

Ultimately, the choice to become a pescatarian is a personal one, driven by a unique combination of health priorities, ethical beliefs, environmental concerns, and lifestyle preferences. When someone identifies as a vegetarian but includes tuna, it is not a contradiction but a reflection of this distinct dietary path. By embracing the flexibility of pescatarianism, individuals can enjoy the benefits of a plant-forward diet while leveraging the nutritional and practical advantages of including fish in their meals.

For more detailed information on the health implications and practical aspects of this dietary style, authoritative resources like Healthline's article on the pescatarian diet offer valuable insights.

Frequently Asked Questions

A vegetarian diet excludes all meat, poultry, and fish. A pescatarian diet also excludes meat and poultry but includes fish and other seafood. The term 'pescatarian' comes from the Italian word for fish, 'pesce'.

Both diets can be very healthy. A pescatarian diet can offer certain advantages, such as easier access to omega-3 fatty acids and vitamin B12 from fish. However, vegetarian diets are also linked to numerous health benefits.

Yes, a potential concern is the risk of mercury and other environmental contaminants found in some fish. It's recommended to choose fish with lower mercury levels and moderate consumption, particularly for certain populations.

Some believe that fish are less sentient or less capable of experiencing pain and suffering than larger land animals, making eating them a more ethically acceptable choice. However, this is a topic of ongoing debate and differing scientific views.

The environmental impact is generally lower than that of diets high in red meat and poultry. However, sustainability varies widely depending on the type of fish and fishing practices, with issues like overfishing and bycatch being significant concerns.

Yes, fish and seafood are excellent sources of high-quality, lean protein. Combined with plant-based sources like legumes, nuts, and seeds, pescatarians can easily meet their protein needs.

For pescatarians, the best sources of omega-3 fatty acids (EPA and DHA) are fatty fish like salmon, sardines, mackerel, and tuna. Shellfish like oysters and mussels also offer significant amounts.