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is a new editorial product that explains the similarities and differences between commonly confused health and medical terms, and why they matter.

Vegan and vegetarian diets are . Both include plant foods, such as fruits, vegetables, legumes and whole grains.

But there are important differences, and knowing what you can and can’t eat when it comes to a vegan and vegetarian diet can be confusing.

So, what’s the main difference?

What’s a vegan diet?

A is an entirely plant-based diet. It doesn’t include any meat and animal products. So, no meat, poultry, fish, seafood, eggs, dairy or honey.

What’s a vegetarian diet?

A is a plant-based diet that generally excludes meat, poultry, fish and seafood, but can include animal products. So, unlike a vegan diet, a vegetarian diet can include eggs, dairy and honey.

But you may be wondering why you’ve heard of vegetarians who eat fish, vegetarians who don’t eat eggs, vegetarians who don’t eat dairy, and even vegetarians who eat some meat. Well, it’s because there are variations on a vegetarian diet:

• a lacto-ovo vegetarian diet excludes meat, poultry, fish and seafood, but includes eggs, dairy and honey

• an ovo-vegetarian diet excludes meat, poultry, fish, seafood and dairy, but includes eggs and honey

• a lacto-vegetarian diet excludes meat, poultry, fish, seafood and eggs, but includes dairy and honey

• a pescatarian diet excludes meat and poultry, but includes eggs, dairy, honey, fish and seafood

• a flexitarian, or semi-vegetarian diet, includes eggs, dairy and honey and may include small amounts of meat, poultry, fish and seafood.

Are these diets healthy?

A looked at the health effects of vegetarian and vegan diets from two types of study.

Observational studies followed people over the years to see how their diets were linked to their health. In these studies, eating a vegetarian diet was associated with a lower risk of developing cardiovascular disease (such as heart disease or a stroke), diabetes, hypertension (high blood pressure), dementia and cancer.

For example, in a of 44,561 participants, the risk of heart disease was 32% lower in vegetarians than non-vegetarians after an average follow-up of nearly 12 years.

Further evidence came from randomised controlled trials. These instruct study participants to eat a specific diet for a specific period of time and monitor their health throughout. These studies showed eating a vegetarian or vegan diet led to reductions in weight, blood pressure, and levels of unhealthy cholesterol.

For example, one combined data from seven randomised controlled trials. This so-called meta-analysis included data from 311 participants. It showed eating a vegetarian diet was associated with a systolic blood pressure (the first number in your blood pressure reading) an average 5 mmHg lower compared with non-vegetarian diets.

It seems vegetarian diets are more likely to be healthier, across a number of measures.

For example, a 2022 combined the results of several observational studies. It concluded a vegetarian diet, rather than vegan diet, was recommended to prevent heart disease.

There is also vegans are more likely to have bone fractures than vegetarians. This could be partly due to a lower body-mass index and a lower intake of nutrients such as calcium, vitamin D and protein.

But it can be about more than just food

Many vegans, where possible, do not use products that directly or indirectly involve using animals.

So vegans would not wear leather, wool or silk clothing, for example. And they would not use soaps or candles made from beeswax, or use products tested on animals.

The motivation for following a vegan or vegetarian diet can vary from person to person. Common motivations health, environmental, ethical, religious or economic reasons.

And for many people who follow a vegan or vegetarian diet, this forms a central part of their .

So, should I adopt a vegan or vegetarian diet?

If you are thinking about a vegan or vegetarian diet, here are some things to consider:

• eating more plant foods does not automatically mean you are eating a healthier diet. Hot chips, biscuits and soft drinks can all be vegan or vegetarian foods. And many , such as plant-based sausages, can be high in added salt

• meeting the for vitamin B12, iron, calcium, and iodine requires more careful planning while on a vegan or vegetarian diet. This is because meat, seafood and animal products are good sources of these vitamins and minerals

• eating a plant-based diet doesn’t necessarily mean all meat and animal products. A healthy flexitarian diet prioritises eating more whole plant-foods, such as vegetables and beans, and less processed meat, such as bacon and sausages

• the recommend eating a wide variety of foods from the five food groups (fruit, vegetables, cereals, lean meat and/or their alternatives and reduced-fat dairy products and/or their alternatives). So if you are eating animal products, choose lean, reduced-fat meats and dairy products and limit processed meats.

Katherine Livingstone receives funding from the ³Ô¹ÏÍøÕ¾ Health and Medical Research Council (APP117380) and the ³Ô¹ÏÍøÕ¾ Heart Foundation (ID106800).