Why is it unhealthy to not eat meat?

December 12, 2025 •

3 min read

Studies reveal that individuals following a vegan or vegetarian diet are at a higher risk of nutritional deficiencies and bone fractures if their diet is not well-planned. This critical fact helps explain why is it unhealthy to not eat meat without considering potential nutrient gaps and the necessity of fortification or supplementation.

Quick Summary

Eliminating meat can result in deficiencies of essential nutrients, such as B12, bioavailable iron, complete proteins, zinc, and omega-3s. A successful meat-free diet requires strategic planning to ensure a complete nutritional profile is maintained through food or supplements.

Key Points

Nutrient Deficiencies: Going meat-free without proper planning can lead to deficiencies in essential nutrients like vitamin B12, iron, zinc, and omega-3 fatty acids.
Bioavailability of Iron: Non-heme iron from plant sources is less efficiently absorbed than heme iron from meat, increasing the risk of iron deficiency anemia.
Protein Quality: Many plant proteins are 'incomplete' and require combining various sources to ensure adequate intake of all nine essential amino acids.
Supplements are Crucial: Vegan diets particularly necessitate supplementation for nutrients like Vitamin B12 and possibly Vitamin D to prevent long-term health problems.
Long-Term Risks: Poorly managed meatless diets have been linked to increased fracture risk, impaired immune function, and potential mental health issues like orthorexia nervosa.
Mindful Planning is Essential: A healthy meat-free diet depends on intentional meal planning, food fortification, and, if necessary, supplementation to replace the nutrients lost from meat.

Understanding the Nutritional Gaps

Transitioning to a meat-free diet, whether vegetarian or vegan, can offer several health benefits, often due to lower saturated fat and higher fiber intake. However, removing meat, a potent source of specific vitamins and minerals, introduces significant nutritional challenges. The key to maintaining good health lies not just in cutting out meat, but in mindfully replacing the nutrients it provides.

The Critical Deficiency of Vitamin B12

Obtaining adequate vitamin B12 is a key challenge for vegans. Found almost exclusively in animal products, B12 is vital for red blood cell formation, neurological function, and DNA synthesis. Deficiency can cause serious issues, including anemia and irreversible nerve damage. Since the body stores B12, deficiency symptoms may take years to appear. Vegans must rely on fortified foods or supplements to prevent these consequences.

Iron Absorption and Heme vs. Non-Heme Iron

Iron absorption differs greatly between animal and plant sources.

Heme iron: Found in meat, poultry, and fish, highly bioavailable (15% to 35% absorption).
Non-heme iron: In plant foods, significantly lower absorption (5% to 12%).

This makes iron deficiency anemia a concern in poorly planned meat-free diets. Plant compounds like phytates further inhibit non-heme iron absorption.

The Importance of Complete Proteins

Meat is a "complete" protein source, containing all nine essential amino acids. Many plant proteins are "incomplete." Careful meal planning to combine various plant proteins throughout the day is needed to get a complete amino acid profile. Inadequate protein can lead to muscle loss and weakened immunity.

Other Micronutrient Concerns

Several other nutrients need attention without meat:

Zinc: Lower bioavailability from plant sources due to phytates. Deficiency impacts immune function and growth.
Omega-3 Fatty Acids (EPA & DHA): Fatty fish are the main source of long-chain omega-3s. While plants provide ALA, conversion to EPA/DHA is poor. Algae-based supplements are a reliable vegan source. Inadequate intake affects cardiovascular and brain health.
Calcium and Vitamin D: Vegans may struggle with calcium without dairy. Both are vital for bone health, and deficiencies increase fracture risk.

Comparison of Nutrient Sources


Nutrient	Omnivore Sources	Vegetarian/Vegan Sources	Deficiency Symptoms (If Inadequate)
Vitamin B12	Meat, eggs, dairy, fish	Fortified cereals, nutritional yeast, supplements	Fatigue, anemia, nerve damage
Heme Iron	Red meat, liver, poultry, fish	N/A	Fatigue, pallor, weakness
Complete Protein	Meat, dairy, eggs, fish	Soy (tofu, tempeh), quinoa, combined proteins (rice & beans)	Muscle loss, weak immunity, fatigue
Zinc	Red meat, seafood, dairy	Legumes, nuts, seeds, fortified cereals	Impaired immunity, hair loss, skin lesions
Omega-3s (EPA/DHA)	Fatty fish (salmon, mackerel)	Algae oil supplements	Cardiovascular and brain health issues

Potential Long-Term Health Risks

Unmanaged nutrient deficiencies can lead to significant long-term health issues. The risk of bone fractures is higher in poorly planned vegan diets. Some studies suggest an increased tendency toward orthorexia nervosa, an eating disorder focused on 'healthy' eating, in those on restrictive plant-based diets. These vulnerabilities stem from a lack of nutritional knowledge and planning, not the diet itself.

Conclusion: Mindful Planning is Key

It's not inherently unhealthy to exclude meat, but the potential for deficiencies requires mindfulness and knowledge. Health outcomes depend on what replaces meat. A well-planned, varied diet of whole plant foods with strategic supplementation or fortification can provide all necessary nutrients. Consulting a registered dietitian is advisable for anyone making a significant dietary change to prioritize health.

For more information on balancing a meat-free diet, the Academy of Nutrition and Dietetics offers valuable resources on nutritional guidelines for vegetarian dietary patterns.

Frequently Asked Questions

Yes, it is possible to get enough protein from a meatless diet, but it requires careful planning. Many plant sources like soy, quinoa, lentils, and nuts offer protein. Combining different plant proteins, such as rice and beans, can create a complete amino acid profile.

The most significant nutritional risk for vegans is a vitamin B12 deficiency. Since this vitamin is naturally found almost exclusively in animal products, vegans must rely on fortified foods (like nutritional yeast and plant-based milks) or regular B12 supplements to maintain adequate levels and prevent serious neurological damage.

Iron from meat, known as heme iron, is more readily absorbed by the body than non-heme iron from plant sources. Plant-based foods also contain compounds like phytates that can inhibit iron absorption further. Vitamin C can help improve the absorption of non-heme iron.

A poorly managed meatless diet can negatively impact bone health. Some studies indicate a higher risk of fractures in vegans compared to omnivores, often linked to lower intakes of calcium, vitamin D, and protein. However, a well-planned vegan diet can mitigate these risks.

While plant foods like flaxseed and walnuts contain ALA omega-3, the body's conversion to the essential EPA and DHA is inefficient. Vegans and vegetarians can get EPA and DHA directly from supplements derived from microalgae.

Yes, insufficient intake of certain nutrients can affect mental health. For instance, low vitamin B12 and omega-3 levels can impact mood and cognitive function. A poorly-planned vegetarian or vegan diet has also been associated with disordered eating patterns in some cases.

Yes. A vegetarian or vegan diet is not automatically healthy. It is possible to consume an unbalanced diet filled with processed foods, sugar, and refined carbs, which can lead to weight gain and nutrient deficiencies, regardless of excluding meat.