Vegetarians are individuals who choose not to consume meat, poultry, or seafood. There are various reasons why people choose to become vegetarians, such as health concerns, religious beliefs, animal welfare, environmental issues, or financial constraints. The availability of fresh produce, more vegetarian food options, and the influence of plant-based diets have made vegetarianism more popular and accessible.

In the past, studies on vegetarianism mainly looked at possible nutrient deficiencies. However, in recent times, the focus has shifted towards the positive effects of meat-free eating. Nowadays, it is widely acknowledged that plant-based diets not only meet nutritional requirements but also help lower the chances of chronic illnesses, including heart disease, cancer, and diabetes type 2.

Concerns about vegetarian diets have mainly focused on nutrients including protein, vitamin B12, iron, zinc, and omega-3 fatty acids. Protein needs can be met through dairy, eggs, peas, beans, lentils, chickpeas, seeds, nuts, soy products, and whole grains. Vitamin B12 is found in animal products but can also be obtained through fortified foods or supplements. Iron absorption from plant foods may be enhanced by vitamin C but inhibited by phytic acid in whole grains, beans, lentils, seeds, and nuts. Furthermore, phytic acid in whole grains, seeds, beans, and legumes can reduce zinc absorption. However, vegetarians in Western countries do not seem to have a zinc deficiency. Additionally, diets without fish or eggs may lack EPA and DHA. Our bodies can convert ALA in plant foods to EPA and DHA, but not very effectively. Vegans can take DHA from algae supplements, which can increase blood levels of DHA and EPA. DHA-fortified breakfast bars and soy milk are also options. Good sources of ALA include flaxseed, walnuts, canola oil, and soy.

It is important to plan your diet appropriately. Simply becoming a vegetarian without following recommended guidelines on nutrition, fat consumption, and weight control may not be beneficial for you. Just because a diet consists of soda, cheese pizza, and candy, it does not mean it is healthy because it is technically “vegetarian.” To maintain good health, it is crucial to consume a wide variety of fruits, vegetables, and whole grains. Additionally, it is important to replace saturated and trans fats with healthy fats found in nuts, olive oil, and canola oil.

You can still enjoy many of the health benefits of a vegetarian diet without fully committing to it. For instance, following a Mediterranean eating pattern, which is associated with a longer life and a reduced risk of chronic illnesses, focuses on plant foods with limited meat consumption. Even if you don’t want to become a complete vegetarian, you can make small changes in your diet, such as incorporating plant-based sources of protein like beans or tofu or choosing fish instead of meat a few times a week.

Different Types of Vegetarians
There are various dietary patterns within the vegetarian community. These include:
Vegans (total vegetarians): These individuals avoid consuming meat, poultry, fish, and any animal-derived products, including eggs, dairy products, and gelatin.
Lacto-ovo vegetarians: Unlike vegans, lacto-ovo vegetarians exclude meat, poultry, and fish from their diet. However, they do include eggs and dairy products.
Lacto vegetarians: Lacto vegetarians refrain from consuming meat, poultry, fish, and eggs. However, they do consume dairy products.
Ovo vegetarians: Ovo vegetarians do not eat meat, poultry, fish, or dairy products. However, they do include eggs in their diet.
Partial vegetarians: These individuals avoid meat but may still consume fish (known as pesco-vegetarian or pescatarian) or poultry (referred to as pollo-vegetarian).

Sources:
https://www.health.harvard.edu/staying-healthy/becoming-a-vegetarian