What's the Difference Between Vegetarian and Pescatarian Diets?

Medically reviewed by Elizabeth Barnes, RDNMedically reviewed by Elizabeth Barnes, RDN

People adopt vegetarian diets for various reasons. Some have ethical reasons, such as not wanting animals killed or harmed. Others cite environmental concerns such as animal waste from factory farms. Some religions promote some type of vegetarian diet. Others follow a vegetarian diet for potential health benefits as they're linked to lower risk of obesity and heart disease and can lower blood pressure.

While the overarching aim is to exclude meat products, a spectrum of vegetarian diets exists, each with its unique guidelines. In addition, there's the pescatarian diet, which, while aligning with vegetarian principles by avoiding meat, introduces seafood into the mix.

Here's a look at vegetarian and pescatarian diets, including their benefits and potential drawbacks, to help you decide which diet might be the right fit for you.

What Is a Vegetarian Diet?

A vegetarian diet is based on consuming plant-based foods, including whole grains, vegetables, fruits, legumes, nuts, and seeds. It eliminates all forms of meat, such as beef, pork, poultry, and lamb, as well as fish and seafood. It may still incorporate animal products like dairy and eggs.

For example:

• Lacto-vegetarian: Includes dairy products such as cheese and milk

• Ovo-vegetarian: Includes eggs

• Lacto-ovo-vegetarian: Includes dairy products and eggs

• Veganism: The most restrictive vegetarian diet, which excludes all meats, fish, seafood, eggs, dairy, and all other animal products (e.g., honey)

What Is a Pescatarian Diet?

The pescatarian diet is a vegetarian diet that includes fish and seafood while excluding all forms of meat (e.g., beef, pork, poultry, and lamb). Like the other types of vegetarian diets, it aims to include more plant-based foods. Some pescatarians include animal products like eggs and dairy.

Benefits of Vegetarian vs. Pescatarian

Healthy vegetarian and pescatarian diets emphasize plant-based, minimally processed foods rich in fiber. Fiber aids gut health and regularity, helps lower LDL cholesterol and blood sugar levels, and can promote weight loss. These diets also reduce saturated fat intake by avoiding meats, potentially lowering the risk of heart disease.

The focus on plant-based foods provides a spectrum of vitamins, minerals, and phytochemicals (beneficial compounds in plants), essential for overall health. Choosing these diets may reduce the risk of chronic diseases like heart disease, diabetes, cancer, high blood pressure, and dementia.

People who follow a vegetarian diet often lose weight compared to those who eat a typical Western diet, which usually includes a lot of highly processed foods, meats, and added sugars. Vegetarians, especially those who are vegan and avoid all animal products, tend to have lower body weights than people who eat meat regularly or omnivores.

The pescatarian diet stands out from other vegetarian diets because it includes fish and seafood. This is significant because fatty fish like salmon and tuna are rich in healthy omega-3 fats called EPA and DHA (eicosapentaenoic acid and docosahexaenoic acid). DHA, the main omega-3 fat in the brain, is crucial for brain function and neurotransmitter activity.

Most research on omega-3 benefits has focused on EPA and DHA from fish or supplements, rather than the omega-3 fat ALA (alpha-linolenic acid) found in plant foods. While ALA can convert into EPA and DHA, the process is not very efficient.

Potential Drawbacks of Vegetarian vs. Pescatarian

When done right, vegetarian and pescatarian diets offer many benefits. However, not all plant-based diets are created equally, and the key lies in how they're planned.

Processed Foods

Unhealthy food choices might include highly processed foods, sugary drinks, and unhealthy fats instead of wholesome options like whole grains, fruits, vegetables, legumes, nuts, and seeds. Such eating habits can increase the risk of obesity, inflammation, and chronic diseases.

Without careful planning, these diets may lack essential nutrients such as vitamin B12, riboflavin (vitamin B2), iron, zinc, calcium, and omega-3 fats. The risk of nutrient deficiency is greater in groups with increased nutrient needs such as pregnant and breastfeeding people and growing children. It's important to ensure adequate intake of these nutrients through supplements or fortified foods.

For example, individuals following a vegan diet should consider taking a vitamin B12 supplement or consuming foods fortified with this nutrient, as foods high in vitamin B12 are primarily meat and meat products. Vitamin B12 deficiency can lead to a type of anemia called megaloblastic anemia. Additionally, a diet deficient in calcium and protein but high in sodium can increase the risk of bone fractures.

Mercury Exposure

Pescatarians who consume a lot of fish, particularly large fish like shark, swordfish, and king mackerel, may be at risk of mercury exposure. Mercury can accumulate in fish and may pose health risks, especially for pregnant women and children.

The Food and Drug Administration (FDA) and the Academy of Nutrition and Dietetics recommend choosing low-mercury fish like salmon, freshwater trout, and canned light tuna to minimize mercury exposure.

Social Challenges

Finally, adopting a vegetarian or pescatarian diet can sometimes pose social challenges, particularly in situations where meat-based dishes are the only available option or when dining out with friends and family who have different dietary preferences.

However, these challenges can be managed by planning, such as eating before attending a social gathering with no plant-based or seafood options, or by communicating dietary preferences to hosts or restaurants in advance.

Similar Diets

The flexitarian or semi-vegetarian diet is an alternative to the vegetarian and pescatarian diets. While vegetarian diets exclude meat entirely and pescatarian diets include fish and seafood but no other meats, the flexitarian diet is more flexible. It allows meat but in smaller amounts than a typical Western diet.

Studies indicate that following a flexitarian diet may positively affect metabolic health and weight loss, reduce blood pressure, and lower the risk of diabetes. For example, one study discovered that postmenopausal women who followed a semi-vegetarian diet had notably lower blood sugar and insulin levels and reduced insulin resistance compared to those who didn't follow this eating pattern.

The Mediterranean diet is another plant-based diet that incorporates a smaller amount of meat. Some experts have likened it to the flexitarian diet. The Mediterranean diet's primary focus is on plant-based foods, fish, and seafood with olive oil being the primary source of fat. Foods are simply seasoned, and small amounts of lean meats, chicken, and eggs are also included. This diet can help lower cholesterol, stabilize blood sugar, and reduce the risk of heart disease, similar to vegetarian and pescatarian diets.

Which Diet Is Best for You?

When deciding between a vegetarian or pescatarian diet, it's essential to consider personal preferences, health goals, accessibility, and cultural and social factors.

A vegetarian diet excludes all types of meat, while a pescatarian diet includes fish and seafood but no other meats. Those concerned about animal welfare or environmental sustainability might lean towards a vegetarian diet, which avoids all animals. On the other hand, individuals seeking the potential health benefits of the omega-3 fats EPA and DHA found in fish may opt for a pescatarian diet.

It's also important to assess accessibility to produce and seafood. In regions with limited or expensive options, individuals may face challenges adhering to either diet.

Cultural traditions and social settings can impact dietary choices, especially when meat-centric dishes are prevalent in certain cultures. Social situations like dining out or attending gatherings also play a role, as individuals may need to navigate meal options with others with different dietary preferences.

Ultimately, the right diet depends on individual needs, values, and lifestyle factors.

A Quick Review

Both the vegetarian and pescatarian diets emphasize incorporating more plant-based, nutritious foods into one's eating habits. They offer a wide array of health benefits, ranging from heart health to blood sugar management. While the vegetarian diet excludes all meat products, including fish, the pescatarian diet includes fish and seafood, making it essentially a variant of the vegetarian diet.

People adopt either of these diets for various reasons, including ethical, environmental, religious, and health considerations. Regardless of the motivation behind choosing a pescatarian or vegetarian diet, it's important to be mindful of food choices and ensure that the diet is rich in essential nutrients, supplementing as needed to maintain optimal health.

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