Which is Healthier, Vegetarian or Vegan? A Deep Dive into Plant-Based Nutrition

November 26, 2025 •

4 min read

According to research from the National Institutes of Health, vegans often have a lower body mass index (BMI) than vegetarians, but also face a higher risk of certain nutrient deficiencies. This complex trade-off is central to determining which is healthier, vegetarian or vegan, as the answer relies on careful planning rather than the diet's label alone.

Quick Summary

An exploration into the health outcomes of vegetarian and vegan diets, detailing their respective nutritional strengths and weaknesses. The healthiest option depends on mindful planning and supplementation to address potential nutrient gaps.

Key Points

Nutrient Gap: Veganism carries a higher risk of deficiencies in B12, calcium, vitamin D, iron, and omega-3s due to the complete exclusion of animal products.
Shared Benefits: Both diets, when well-planned, can lower the risk of heart disease, type 2 diabetes, and obesity compared to omnivorous diets.
Meticulous Planning: For a vegan diet to be healthy, B12 supplementation is essential, and careful planning is needed for other nutrients.
Flexibility Advantage: Vegetarianism, especially lacto-ovo, offers a more flexible approach with fewer inherent nutritional concerns because it includes dairy and eggs.
Whole Foods are Key: The healthfulness of either diet depends more on a focus on whole, minimally processed plant foods than on the specific diet label.
Body Composition: Vegans tend to have a lower BMI than vegetarians, suggesting a potential advantage in weight management.
Risk vs. Reward: While a strict vegan diet may offer some additional health advantages, it comes with a greater risk of nutrient deficiencies that must be actively managed through diet and supplementation.

Defining Vegetarian and Vegan Diets

To understand which is healthier, it's important to know the difference. A vegetarian diet excludes meat, poultry, and fish but typically includes animal products like dairy and eggs. A common type is the lacto-ovo-vegetarian, which allows both. A vegan diet is stricter, omitting all animal products, including eggs, dairy, and honey. Veganism often extends beyond diet to a broader lifestyle. This distinction affects their nutritional profiles.

The Common Health Benefits of Plant-Based Diets

Both diets offer significant health benefits compared to typical Western diets, largely due to higher intake of fruits, vegetables, whole grains, and legumes.

Cardiovascular Health: Both diets are linked to a lower risk of heart disease, attributed to less saturated fat and more fibre, which helps reduce LDL cholesterol.
Lower Body Mass Index (BMI): Vegetarians and vegans generally have lower BMIs than meat-eaters, contributing to a lower risk of obesity and related chronic diseases.
Type 2 Diabetes: Plant-based diets, particularly veganism, are associated with a reduced risk of type 2 diabetes due to better blood sugar control and weight management.
Certain Cancers: While some studies suggest a lower overall cancer risk, findings for specific cancers can vary and depend on other lifestyle factors.
Higher Fibre Intake: Both diets are high in fibre, beneficial for gut health, digestion, and satiety.

Key Nutritional Differences and Challenges

The exclusion of certain food groups creates specific nutritional challenges for each diet. Proper planning is vital to avoid deficiencies.

Vegan Diet Challenges

Vegans must pay close attention to several nutrients, often requiring supplements or fortified foods.

Vitamin B12: Primarily found in animal products, B12 deficiency is a high risk for vegans and can cause irreversible neurological damage. Vegans must supplement B12.
Calcium and Vitamin D: Vegans need non-dairy sources like fortified plant milks, tofu, and leafy greens for calcium. Vitamin D, found in eggs and dairy and produced from sunlight, also needs attention.
Omega-3 Fatty Acids (EPA & DHA): While plant sources provide ALA, conversion to EPA and DHA is poor. Algae-based supplements are often recommended.
Iron and Zinc: Plant sources contain these minerals, but they are less easily absorbed than from animal products. Consuming them with vitamin C can help absorption.

Vegetarian Diet Challenges

Including eggs and dairy reduces some nutritional concerns, but planning is still necessary.

B12 and Calcium: Lacto-ovo-vegetarians typically get enough B12 and calcium from dairy and eggs.
Iron: Non-heme iron from plants can be a concern, though less so than for vegans. Pairing with vitamin C is beneficial.
Omega-3s: Intake varies based on egg and dairy consumption, but optimal levels often require other sources.

Comparison: Vegetarian vs. Vegan Health Outcomes

The table below highlights key health differences based on research:


Feature	Vegetarian Diet (Lacto-Ovo)	Vegan Diet	Key Health Takeaway
Saturated Fat & Cholesterol	Lower than omnivores, present from dairy/eggs.	Typically lowest due to no animal products.	Vegans may have greater LDL cholesterol reduction.
Nutrient Deficiency Risk	Lower risk for B12, Calcium, D due to animal products.	Higher risk for B12, Calcium, D, Zinc, Omega-3s; supplementation needed.	Vegetarian offers more flexibility; vegan requires meticulous planning.
Bone Mineral Density (BMD)	Some studies show lower BMD than meat-eaters, less than vegans.	Consistently lower BMD in studies, linked to nutrient intake.	Vegans need to focus on calcium, vitamin D, and protein for bone health.
Fracture Risk	Increased risk compared to meat-eaters in some studies.	Higher risk of fractures reported in research.	Highlights need for balanced nutrition and sufficient mineral intake for vegans.
Weight Management	Lower BMI than omnivores.	Often lower BMI than vegetarians and omnivores.	Both are effective, but vegans may show slightly more fat loss.
Lifestyle Factors	Primarily dietary restriction.	Comprehensive ethical lifestyle choice.	Choice depends on personal ethics and commitment.

The Role of Whole Foods and Supplementation

Neither diet guarantees health; focusing on whole, minimally processed plant foods is crucial. This includes fruits, vegetables, legumes, whole grains, nuts, and seeds. According to the Academy of Nutrition and Dietetics, well-planned versions of both diets are suitable for all life stages if nutritional needs are met. Vegans almost always need B12 supplements and often others like omega-3s, vitamin D, and potentially iron or iodine. Vegetarians may need supplements less frequently.

Conclusion

There is no single answer to which is healthier, vegetarian or vegan; it depends on how well the diet is planned. Both offer significant health benefits over typical Western diets due to more whole plant foods and less saturated fat. However, the strict nature of a vegan diet brings a higher risk of specific nutrient deficiencies, especially B12, calcium, and vitamin D, requiring diligent supplementation and planning. A vegetarian diet with dairy and eggs makes obtaining these nutrients easier. While a well-planned vegan diet might offer slightly more benefits like lower cholesterol, these potential gains must be weighed against the increased risk of deficiencies if not managed properly. The healthiest diet is diverse, nutrient-rich, and individualized. Consulting a registered dietitian is recommended when making a dietary switch.

Position of the Academy of Nutrition and Dietetics: Vegetarian Diets

Frequently Asked Questions

The main difference is the inclusion of animal products. A vegetarian diet typically includes dairy and eggs, providing readily available sources of vitamin B12, calcium, and protein. A vegan diet excludes all animal products, requiring supplementation for B12 and careful planning for calcium and other minerals.

Yes, vitamin B12 supplementation is mandatory for anyone following a vegan diet, as it is not naturally present in plant foods. Vegans may also need to consider supplements for omega-3 fatty acids (EPA/DHA), vitamin D, and potentially other nutrients based on their individual intake and blood test results.

Yes, both vegetarians and vegans can be at a higher risk of iron deficiency, as the non-heme iron from plants is less bioavailable than heme iron from meat. However, this can be mitigated by eating iron-rich plant foods like legumes and leafy greens paired with vitamin C to enhance absorption.

A vegan diet can be less healthy if it is not properly planned and supplemented. An unbalanced vegan diet heavy in processed foods, refined grains, and sugars can be nutritionally poor and less healthy than a well-rounded vegetarian diet that includes nutrient-dense foods like eggs and dairy.

Both diets are often effective for weight loss due to higher fibre intake and lower saturated fat. Studies suggest vegans may have a slight edge with a lower average BMI, but overall weight loss success depends heavily on the quality of food choices.

A vegan diet is generally considered to have a lower environmental impact due to the complete exclusion of animal products, including dairy and eggs, which contribute significantly to greenhouse gas emissions.

Yes, according to the Academy of Nutrition and Dietetics, both well-planned vegetarian and vegan diets are appropriate for all stages of life, including childhood. However, professional guidance is especially important for growing children to ensure all nutritional needs are met.