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Pescatarian diet: pros, cons, and what you can eat

In Britain today, around 2.4 million of us follow a pescatarian diet. As this type of meat-free diet continues to grow in popularity, let's take a look at what you can and can't eat. Is being pescatarian really good for you? Or is there something too fishy about this diet choice?

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What is a pescatarian?

You've likely heard of vegetarianism and veganism, but did you know that there are other possible gradients of a meat-free diet? For example, semi-vegetarianism (also known as being flexitarian) involves following a mostly vegetarian diet that's occasionally supplemented with any type of meat.

The pescatarian diet is neither fully nor semi vegetarian. A vegetarian avoids eating all animal meats:

  • Red meat - meat from livestock animals such as cows, pigs, and lambs.

  • Poultry (also called white meat) - meat from birds such as chickens, turkeys, and ducks.

  • Seafood - meat from aquatic life such as all fish, crustaceans (eg, lobster and crab) and molluscs (eg, scallops and mussels).

A pescatarian, on the other hand, is someone who eats a vegetarian diet with the addition of fish and other seafood but no other types of meat. In fact, this is the only prerequisite for pescatarianism, and in this way the diet is quite simple to grasp.

As a pescatarian, exactly how much fish you eat is completely down to you - there is no limitation. Many pescatarians also eat non-meat animal products - ie eggs and dairy products - while others choose not to.

What do pescatarians eat?

Pescatarians can consume all products containing types of fish and other seafood, including:

  • Salmon.

  • Tuna.

  • Cod.

  • Prawns.

  • Scallops.

  • Crab.

  • Lobster.

  • Squid.

For a balanced diet, they should also eat a range of vegetarian foods, including:

  • Fruit and vegetables.

  • Whole grains and cereals (such as rice, bulgur wheat, and oats).

  • Legumes (such as all types of beans and peas).

  • Nuts and seeds (such as flaxseeds and chia seeds).

  • Eggs and dairy, if lacto-ovo-vegetarian (such as eggs, cheese, and milk).

Why do people become pescatarian?

Of the 7.2 million British adults currently following a meat-free diet, pescatarians are the second biggest group1. They currently make up around 5% of the population, and this figure is expected to climb.

UK diets

UK diets

There are many possible reasons for becoming a pescatarian. Here are some of the most common:

  • Ethical motivations - some people are against killing animals for food. While fish are also living creatures, transitioning from an omnivore (meat and plant-based) diet to a pescatarian diet is more manageable for some meat lovers and still limits animal consumption. What's more, the conditions in which many land animals (livestock) are raised for slaughter are often seen as poor and inhumane.

  • Environmental concerns - Raising livestock also comes with an environmental cost - the practice is responsible for 15% of all man-made carbon emissions2, making a sizeable contribution to the global warming crisis. In comparison, people who eat fish are thought to cause around 46% fewer greenhouse gas emissions than those who eat at least one serving of other meat a day3.

  • Health benefits - limiting your meat intake is associated with a lower risk of several health issues, including obesity4, type 2 diabetes5, and heart disease6.

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Is the pescatarian diet healthy?

According to Clare Thornton-Wood, registered dietitian and British Dietetic Association (BDA) member, a balanced pescatarian diet has many health benefits:

"A pescatarian diet typically includes lots of lean protein in the form of white fish, and plenty of omega-3 fatty acids from oily fish such as salmon, mackerel, fresh tuna, and sardines."

  • Omega-3 fatty acids - 'healthy fats' that help keep your heart, blood vessels, lungs, and immune system healthy.

  • Protein - a nutrient needed for many important functions, including the growth and repair of cells, muscle health, bone health, hormone regulation, and digestive health.

  • Many types of fish are a good source of omega-3 fatty acids and lean protein.

"Coupled with whole-grain cereals, nuts, fruit, vegetables and small amounts of dairy, this forms the basis of the Mediterranean diet which is widely recognised as one of the healthiest lifestyle diets."

Patient picks for Healthy eating

There is also good evidence to demonstrate how the pescatarian diet may help to prevent several serious health problems, including:

Drawbacks of a pescatarian diet

Ensure your diet is varied and balanced

"There aren't really any drawbacks of a pescatarian diet, as long as you eat a variety of foods," says Thornton-Wood.

As with all diets, it's all about making sure you're getting enough of the nutrients and minerals you need. For example, red meat is high in iron, so as this is omitted from the pescatarian diet, Thornton-Wood recommends alternative sources of iron "such as eggs, green leafy vegetables, molasses (add to smoothies) and fortified breakfast cereals.

"If you also exclude eggs and dairy, then getting adequate amounts of calcium, zinc, vitamin B12, and iodine can also sometimes be difficult. Good food choices include fortified plant milks."

Mercury poisoning

Before alarm bells ring in your ear, the small amount of the toxin mercury found in oily fish is usually harmless - you would need to eat a lot to be at risk of mercury toxicity. Still, it's worth knowing, particularly if you are pregnant, breastfeeding, or planning to conceive:

"The NHS advises that this group should consume no more than two portions of oily fish per week as it could be harmful in excess to the developing fetus or newborn baby," Thornton-Wood cautions.

"Sea bream, bass, turbot, halibut, and rock salmon also need to be limited as they are higher in mercury than white fish. Shark, swordfish, and marlin contain much higher quantities and should be completely avoided by this group, while the rest of the population should limit intake to one portion per week."

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Do pescatarians need supplements?

"Usually, if you are eating a balanced diet that includes a variety of foods from all food groups excluding red meat and poultry, then you won't need supplements," advises Thornton-Wood.

However, if you're worried that you're not obtaining adequate levels of certain nutrients from plant-based foods, a general multivitamin and mineral supplement might be useful. A pharmacist can help you purchase the right supplement for you. If you have any serious concerns about nutrient deficiencies, it's best to consult your GP or a dietitian.

How to become a pescatarian

Thornton-Wood's starter tips:

  • Start gradually if you find this easier, replacing one meat meal at a time with a fish or plant-based one.

  • Consider other plant-based sources of protein - such as lentils and pulses - and don't wholly rely on fish for protein. Where possible, aim for a couple of different sources each day.

  • Eat a variety of fish and seafood and aim to get these from sustainable sources.

  • Try to keep your intake of processed foods to a minimum. People often swap meat products for processed meat substitutes, which are frequently high in salt and saturated fat.

Further reading

  1. Finder, "How many vegetarians and vegans are in the UK?".

  2. Food and Agriculture Organization of the United Nations, "Key facts and findings".

  3. Scarborough et al. "Dietary greenhouse gas emissions of meat-eaters, fish-eaters, vegetarians and vegans in the UK".

  4. Rosell et al. "Weight gain over 5 years in 21,966 meat-eating, fish-eating, vegetarian, and vegan men and women in EPIC-Oxford".

  5. Tonstad et al. "Type of vegetarian diet, body weight, and prevalence of type 2 diabetes".

  6. Key et al. "Mortality in vegetarians and non-vegetarians: a collaborative analysis of 8300 deaths among 76,000 men and women in five prospective studies".

  7. Zhang et al. "Fish consumption and coronary heart disease: a meta-analysis".

Article history

The information on this page is peer reviewed by qualified clinicians.

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