Plant-Based, Vegetarian and Vegan Diets

What is it?

“Plant-based” is an umbrella term for eating patterns that emphasize foods from plants. It does not always mean that a person avoids all animal foods.

Common patterns include: vegan, plant foods only, excluding meat, fish, eggs, dairy and usually honey; vegetarian, usually excludes meat, poultry and seafood but may include eggs and dairy; lacto-vegetarian, includes dairy but not eggs, meat, poultry or seafood; ovo-vegetarian, includes eggs but not dairy, meat, poultry or seafood; lacto-ovo vegetarian, includes dairy and eggs but excludes meat, poultry and seafood; pescetarian, includes fish, seafood, eggs and dairy but excludes meat and poultry; and flexitarian, mostly plant-based but includes small or occasional amounts of meat, poultry, fish, eggs, or dairy.

Terminology can vary, so a person should describe the actual foods they eat rather than relying only on a label.

What the diet emphasizes and limits

Most plant-based patterns emphasize vegetables and fruits; beans, lentils, monggo, peas and soy foods; whole grains; nuts and seeds; and tofu, tempeh and other plant proteins.

The excluded foods depend on the pattern. A vegan diet excludes all animal products. A lacto-ovo vegetarian diet allows milk, yogurt, cheese and eggs. A pescetarian diet allows seafood. A flexitarian diet has no absolute exclusion but generally limits animal foods.

A plant-based diet can still be high in sugar, salt, refined flour, or highly processed meat substitutes. “Plant-based” does not automatically mean nutritionally balanced.

Where it came from

Plant-based eating is not a single modern fad. Vegetarian and vegan practices have roots in religious, ethical, cultural, environmental and health traditions.

Modern nutrition research has examined these patterns for weight management, diabetes, cardiovascular health and sustainability. The term “plant-based” is now used to describe anything from adding more vegetables and beans to following a fully vegan pattern.

What the evidence says

A 2024 systematic review of seven randomized trials involving 770 adults with type 2 diabetes found that vegetarian dietary patterns probably reduced HbA1c and body mass index compared with nonvegetarian patterns. Some participants were also able to reduce diabetes medicines, although the certainty of that evidence was lower.

In an 8-week randomized clinical trial involving 22 pairs of identical twins, participants assigned to a healthy vegan diet had greater reductions in LDL cholesterol, fasting insulin and body weight than their twins assigned to a healthy omnivorous diet. The study was small and short, so it cannot establish long-term effects for everyone.

An umbrella review also found possible improvements in weight, glucose and LDL cholesterol with plant-based diets, but noted that many studies were based on Western food patterns and had limitations in quality and consistency.

Who may benefit and who should be careful

Many adults may benefit from eating more vegetables, fruits, beans, whole grains, nuts and seeds, whether or not they become vegetarian or vegan.

Plant-based diets may be useful for adults who want to reduce meat consumption, improve fiber intake, or support cardiometabolic health. They can be adapted to familiar Filipino foods such as monggo, tofu, vegetables, fruits, peanuts and rice or other grains.

Strict vegan diets require planning. Vitamin B12 is naturally found mainly in animal foods, so vegans need reliable fortified foods or supplementation. Iron, calcium, iodine, zinc and omega-3 fats may also require attention.

Pregnant or breastfeeding people, children, adolescents, older adults and people with chronic disease should seek individualized nutrition advice before making major restrictions. People taking diabetes medicines may also need monitoring if their food intake changes significantly.

Takeaway

Plant-based eating is not one diet. It ranges from adding more vegetables to following a fully vegan pattern.

The healthiest version emphasizes variety, adequate protein, fiber and essential nutrients. A person does not need to adopt the most restrictive version to receive benefits from eating more plant foods.