Introduction

Vegetarianism has become more popular in recent years, with many people started to consider adopting a vegetarian diet for various reasons. The history of vegetarianism has been associated with beliefs and religions before scientific observations of potential health benefits associated with reduced animal product consumption, which have strengthened the practice of vegetarianism. Nowadays, this adoption of a vegetarian diet could be related to health and physical benefits, ethical concerns, environmental-related, and social or religious factors.^1,2

Generally, following a vegetarian diet means excluding meat from your diet. However, exploring different types of vegetarian diets reveals specific types of food that can be consumed and those that must be excluded. There are also less restrictive types of vegetarian diets that even still allow you to consume meat once a week or the ones that still allow fish and seafood.¹

Main types of vegetarian diets

• Lacto-ovo vegetarian 
• Lacto-vegetarian 
• Ovo-vegetarian
• Vegan diet
• Others including flexitarian diet and the pescatarian diet

Lacto-ovo vegetarian

This vegetarian diet is plant-based and avoids the consumption of meat, fish, and poultry. However, it does include moderate amounts of dairy products and eggs. “Lacto” refers to daily products and “ovo” means eggs. Therefore, this type of vegetarian diet allows you to still consume these products.³ Most vegetarians are lacto-ovo vegetarians as it is relatively considered the healthiest type of vegetarian diet.⁴

Health benefits of lacto-ovo vegetarian diets:

• Aid in weight loss and maintenance of a healthy body mass index (BMI). Compared to non-vegetarian diets, lacto-ovo diets seem to offer a more significant advantage in weight loss⁵
• Decreases the risk of coronary arterial disease (CAD) by regulating lipid profiles⁶
• Lower the risk of cancer in general and gastrointestinal tract cancers compared to non–vegetarian diet³

Lacto-vegetarian diet

Lacto-vegetarian diet excludes meat, fish, poultry, and seafood, similar to other vegetarian diets. However, unlike lacto-ovo vegetarians who can eat eggs, lacto-vegetarians specifically exclude eggs while incorporating dairy products such as milk, cheese, and yoghurt into their diet.⁷

Health benefits of lacto-vegetarian diet:

• May aid in weight loss or maintaining a healthy weight
• Reduces the risk of developing diabetes
• Lowers the risk of high blood pressure and heart disease
• Alleviates symptoms of depression
• Improves your overall physical fitness⁸

However, it’s important to note that this diet may not be suitable if you have a milk allergy or are lactose intolerant.⁸

Ovo-vegetarian diet

The ovo-vegetarian diet excludes animal protein while incorporating eggs and egg-based foods, such as baked goods. However, the ovo-vegetarian diet is less widespread compared to other types, notably the vegan diet. Eggs serve as the primary source of animal-derived protein for ovo-vegetarians, offering versatility in meal preparation, including scrambled, poached, boiled, omelettes, or incorporated into various dishes like baked goods.

Similar to other vegetarian diets, the ovo-vegetarian approach is associated with several health benefits, including a reduced risk of high blood pressure, type 2 diabetes, and aiding in weight management.⁹

Vegan diet

A vegan diet abstains from foods that come from animal sources, it relies only on plant-based foods. As a vegan, it is essential for you to eat a varied and balanced plant-based diet includes fortified foods and supplements.¹⁰

The advantages and disadvantages of being a vegan have been highlighted in research. One of the most frequently mentioned advantages is a decreased risk of cardiovascular and metabolic diseases (heart disease, type 2 diabetes, obesity, and non-alcoholic fatty liver disease).

However, a vegan diet may also pose a risk of macronutrients and micronutrient deficits that lead to various forms of disorders including nervous, skeletal, and immune system impairments, haematological disorders, and mental health problems. It is highly recommended to closely monitor and address nutritional deficiencies to mitigate long-term negative health outcomes, especially for vulnerable populations.¹¹

Other variants of vegetarian diets

Flexitarian diet

Generally, a flexitarian diet is defined as a semi-vegetarian, plant-forward diet. It is a flexible eating style that focuses on plant-based foods while allowing occasional consumption of meat and other animal products. It emphasises the addition of plant-based foods, including dairy and eggs, and reducing the frequency and portion size of meat intake. 

Several studies suggest that the flexitarian diet has a positive impact on health, improving markers of metabolic health, reducing blood pressure, and decreasing type 2 diabetes risk. Additionally, research indicates that a semi-vegetarian diet may play a role in the treatment of inflammatory bowel diseases such as Chron’s disease.

This diet allows more flexibility which might be interesting if you are looking for a way to improve health with less rigid rules. The main principle of the flexitarian diet is to gradually increase your intake of plant-based food while still including animal-derived foods.¹²

Pescatarian diet

Another type of vegetarian diet is the pescatarian diet, which allows you to consume fish and seafood products.¹³ The seafood options may include saltwater fish such as salmon and tuna, shellfish like shrimp, oysters, and clamps, as well as freshwater fish like trout or perch. This diet is rich in vitamins, minerals, fibre, and phytochemicals, and low in saturated fat, which is associated with decreased risk of cardiovascular diseases and other health conditions.¹⁴

Maintaining a balanced diet as a vegetarian

Despite ethical and environmental concerns, many people choose to become a vegetarian or vegan due to its promising health benefits. As mentioned above, a vegetarian diet, in general, has evidence to decrease the risk of heart disease, metabolic disease, especially diabetes, cancer, and high blood pressure, and helps maintain a healthy body mass index. 

However, you need to always remember that it is crucial to maintain balance. A balanced vegetarian or vegan diet entails obtaining essential nutrients, vitamins, and minerals from a diverse array of sources.

Since this diets typically exclude meat, there is a risk of protein and vitamin B12 deficiencies. Additionally, for the types of diets that exclude eggs and dairy products, monitoring calcium and vitamin D intake becomes essential. 

Nutritional considerations for vegetarians: 

• try to avoid or limit the consumption of foods high in sodium, added sugar, and saturated fat
• choose high-protein foods that are still allowed to be consumed in the diet
• be mindful of carbohydrate intake
• ensure adequate intake of vitamin B12 and calcium
• choose vitamin D-fortified foods¹⁵

FAQs

What are the four main types of vegetarians?

• Lacto-ovo vegetarian: This diet allows you to consume dairy products and eggs
• Ovo-vegetarian: Include eggs in the diet, but dairy products are excluded
• Lacto vegetarian: Include dairy products but exclude eggs
• Vegan: exclude all types of animal-derived foods, only plant-based

Can vegetarians eat cheese?

Different types of vegetarian diets determine which foods you can eat. Lacto-ovo and lacto-vegetarian diets are among those that include cheese.

Do vegetarians drink milk?

The lacto-ovo and lacto vegetarians are still allowed to consume dairy products including milk.

Are vegetarians healthier?

People who choose to be vegetarian have several reasons behind their decision, including health benefits, ethical and environmental concerns, religious beliefs, and social factors. Numerous studies suggest that excluding animal-derived products from the diet can help reduce the risk of various diseases including arterial coronary disease, hypertension, diabetes type 2, cancer, and mental health problems. It’s also recognised for aiding weight management 

However, despite those benefits, there are also risks of negative outcomes associated with becoming a vegetarian, most commonly related to a deficit in macro and micronutrients. Therefore, maintaining a balanced diet and ensuring adequate intake of all essential nutrients is crucial.^15,16

What to eat instead of meat?

Getting protein doesn’t always require you to eat meat. There are more plant-based options available to fulfil protein needs. These include:^17,18

• soya beans (tofu, soya milk, tempeh)
• pulses
• plant-based sausages, plant base meat, and plant-based chicken
• nuts and seeds
• cereals and grains
• dairy and eggs (if your diet type still allows it)

Summary

Vegetarian diets involve excluding animal products from your meals, with the specific exclusions varying depending on the type of diet. People adopt these diets for various reasons related to health benefits, social factors, religious beliefs, and environmental or ethical concerns.

The main types of vegetarian diets are:

• Lacto-ovo diet: This type of diet excludes meat, fish, seafood, and poultry, but allows the consumption of dairy products and eggs
• Lacto vegetarian: Excludes meat, fish, seafood, poultry, and eggs, but includes dairy products such as milk, cheese, and yoghurt
• Ovo-vegetarian: This type allows you to still eat eggs but is unable to eat other animal products.
• Vegan: Excludes all animal-derived products, only able to consume plant-based foods

Additional types of vegetarianism:

• Flexitarian diet: Emphasises plant-based foods but allows you to occasionally consume meat and other animal products
• Pescatarian diet: Allows you to eat fish and seafood while excluding all other forms of animal-sourced foods