Rob Hobson April 30, 2019

Whether you're looking to improve your health, do your bit for the planet or both, there's a diet for you. Here, nutritionist Rob Hobson looks at the differences between vegan, vegetarian and pescatarian diets and explains what you can do to stay healthy when following them.

Vegan diet

Bowl of vegan food including jackfruit, avocado, oranges, purple food, grains

What can't you eat? Any products derived from animals, such as meat, dairy and eggs. Foods made using animal products aren’t allowed either – so no sweets containing gelatine. Most vegans avoid honey, too.

What nutrients could you be deficient in? Public Health England suggests that every person eats two portions of fish per week, one of which should be oily. This is to make sure we consume enough omega-3 fatty acids, which are abundant in oily fish. Vegans are often lacking in iron, vitamin B and calcium. And it can be difficult to get enough protein if you only eat plant-based foods.

What to eat to make up for deficiencies Beans and pulses should be staples of the vegan diet. Not only are they high in protein, they're stacked with fibre which is something most adults don't eat enough of. It’s worth considering a good multivitamin if you're vegan, too, to cover any potential deficiencies.

Pescatarian diet

A piece of salmon with parsley and lemon. Cucumber sliced into ribbons and roasted tomatoes

What can't you eat? A pescatarian doesn't eat meat, but will eat fish. This is often a stepping stone towards a vegetarian diet.

What nutrients could you be deficient in? Vitamin B12 only occurs naturally in animal products, so supplementing or sourcing fake meat that contains vitamin B12 is a good idea. This goes for all diets that don’t include meat. Iron is a big one here, too.

What to eat to make up for deficiencies Up your vegetable intake including broccoli and spinach, which are both high in iron. You can look for fortified breakfast cereals, but make sure they aren’t packed with refined sugar.

Vegetarian diet

Loads of green vegetables including cauliflower, a glass bottle of milk, some white bread, tomatoes and nuts scattered on a wooden surface.

What can't you eat? No vegetarians eat meat, but there are three categories when it comes to whether they eat eggs or dairy: lacto-vegetarians, ovo-vegetarians and lacto-ovo vegetarians (see below).

What nutrients could you be deficient in? Again, the absence of read meat means a vegetarian diet may lack sufficient iron. If you don't eat eggs or dairy, a lack of zinc and calcium could be a problem.

What to eat to make up for deficiencies Because vegetarians don’t eat two portions of fish a week, it's important they either supplement with omega-3 or source it from other foods, such as flaxseed oil. Some plant-based milks are fortified with calcium, so opt for those. Finally, snack on nuts to up your intake of the mineral zinc.

Not all vegetarians are alike

two icons representing vegetables and dairy

Lacto-vegetarians dairy but not eggs

two icons representing vegetables and eggs

Ovo-vegetarians eggs but not dairy

3 icons representing vegetables, dairy and eggs

Lacto-ovo vegetarians eggs and dairy

And flexitarians?

What is flexitarianism?

Becoming a flexitarian is a way of making positive changes to your health and the environment, without drastically changing your food habits. We've seen a spike in this diet from environmentally conscious people who don't want to give up meat entirely, but know they need to reduce their intake. The same goes for those cutting down on red meat for health reasons.

Other popular diets

The planetary diet

White bowl filled with avocado, spinach, sweetcorn. grains, tomatoes, beetroot, red onion and cucumber

Published by journal The Lancet, the planetary diet offers a double win for the world's population - expected to rise to ten billion by 2050. Not only could the diet lead us away from a global environmental crisis, it’s estimated it would prevent 11 million of the total deaths caused annually by unhealthy eating.

Unsurprisingly, the planetary diet means cutting back on meat, fish, eggs and sugar and consuming more vegetables, fruits, pulses and nuts. The diet banishes no food group, but makes cuts to problem areas like red meat. Here are the total amounts of each type food you're allowed to eat per day:1

Whole grains 232
Tubers or starchy vegetables 50
Vegetables 300
Fruits 200
Dairy foods 250 One glass of milk 153
Beef, lamb and pork 14 Roughly one small burger a week 30
Chicken and other poultry 29
Eggs 13 Roughly two a week 19
Fish 28
Legumes 75
Nuts 50
Unsaturated oils 40
Saturated oils 11.8
All sugars 31

Aside from food restrictions, the Planetary diet recommends eating sustainably and supporting regenerative farming practices, cooking at home if possible and reducing food waste by planning your meals carefully and eating leftovers from dinner for lunch the next day.

The paleo diet

Almonds in a square bowl, walnuts on a plate, boiled eggs, broccoli, black lentils

Essentially a diet void of processed foods (see definition below), following the paleo diet consists of foods that can be hunted, fished or gathered. Otherwise known as the 'Caveman diet', it harks back to the Palaeolithic era more than two million years ago, and rules out any fast food or snacks like crisps and chocolate or sweets.

Eating the caveman way means sticking to lean meat and natural ingredients like berries, nuts, seeds, fruits and fish. Though an official paleo diet doesn't exist, diets using the term tend to be high in protein and low in carbohydrates.

The paleo diet is worth looking at if you don’t want to reduce your meat consumption, but do want to cut down your intake of things like refined sugar and highly processed carbohydrates.

If followed correctly, the paleo way of eating says no to wholegrains and legumes. It's probably best to ignore this rule, as both of the above are crucial for the intake of fibre, which is lacking from so many adult diets in sufficient quantities. Wholegrains and legumes also keep you full and your blood glucose (sugar) levels healthy.

Maintaining healthy glucose levels

Although glucose is fuel for your organs, muscles and brain, too much of it can lead to diabetes and, in the long term, it can cause damage to organs, nerves and blood vessels. Foods that encourage unhealthy blood sugar spikes include refined carbohydrates and fruits with high levels of fructose. If you eat a pizza, for example, the dough and the sugar in the sauce (if it's not homemade) will cause a sudden spike, whereas the protein and fat in the pizza will affect your levels gradually for the next couple of hours. In that sense, the paleo diet recommends foods that don't cause a glucose spike and bans those that do.

The five levels of processed food

Introduced in 2009, the Nova system classifies processed foods into five categories: unprocessed, minimally processed, processed culinary ingredients and ultra-processed foods2. Here's what that means:

Unprocessed or minimally processed foods are ingredients in their raw form, such as fruit, vegetables, chicken, nuts or seeds. Essentially, anything that hasn’t undergone alteration after it's been taken from nature.

Minimally processed foods have been altered slightly or 'cleaned'. This involves processes like fermenting, pasteurisation, drying, cooling or freezing. Dried herbs and spices, milk and frozen shellfish or meat all count.

Processed culinary ingredients are foods that have been extracted from their natural source, such as olive oil from olives, syrup extracted from maple trees or honey extracted from honeycomb.

Processed foods are 'versions of original foods' that have been altered to stay fresh for longer or to taste better. Think bacon, cured meats, wine, canned tuna and tomato extract.

Ultra-processed foods - a real health threat - are made either entirely from processed foods or formulated in laboratories. To put that into perspective, ultra-processed foods tend to be void of any unprocessed or minimally processed foods (number 1 of the Nova classification). The list includes chicken nuggets, hot dogs, some sausages, instant soups, confectionery, energy drinks, pre-prepared pizza and pasta dishes and breakfast cereals and bars.

For more information about supporting your vegan lifestyle, see our vegan advice hub.

1The Lancet Commission Summary Report (2019). Healthy diets from sustainable food systems,
2NOVA. The star shines bright, World Nutrition Volume 7, Number 1-3, January-March 2016.

Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn't possible, supplements can help. This article isn't intended to replace medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.



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