What Do Vegetarians Suffer From? Essential Nutritional Considerations

January 13, 2026 •

4 min read

According to a systematic review published in 2024, vegetarians and vegans are consistently at a higher risk of deficiency or inadequate intake of key nutrients like vitamin B12, vitamin D, and iron, compared to omnivores. This raises the important question: what do vegetarians suffer from if they don't plan their diet carefully to compensate for missing animal-based nutrients?

Quick Summary

Vegetarian diets, if not carefully planned, pose risks of deficiencies in vital nutrients like vitamin B12, iron, calcium, and zinc due to bioavailability and intake issues. Proper planning, fortification, and supplementation can mitigate these health risks. Potential issues include anemia, weakened bones, and impaired immunity, but these are manageable with knowledge and attention.

Key Points

Vitamin B12 Deficiency: Vegetarians and especially vegans risk B12 deficiency, which can cause neurological problems and anemia, since it is found almost exclusively in animal products.
Iron Absorption Issues: The non-heme iron in plants is less bioavailable than the heme iron in meat, leading to a higher risk of iron deficiency and anemia in vegetarians despite adequate intake.
Bone Health Concerns: Vegans may have lower bone mineral density due to lower intake of calcium and vitamin D, both crucial for skeletal health.
Zinc Bioavailability: Plant foods contain phytates that inhibit zinc absorption, putting vegetarians at risk for impaired immunity and other deficiency symptoms.
Omega-3 Fatty Acid Imbalance: Plant-based diets lack readily available EPA and DHA, relying on inefficient ALA conversion, impacting brain and heart health.
Mitigation Strategies: Proper planning, incorporating fortified foods, and supplementation are essential to prevent deficiencies, especially for vegans and strict vegetarians.

A well-planned vegetarian diet can be healthy and provide many benefits, but a meat-free diet requires careful attention to avoid certain nutritional deficiencies. Some nutrients, primarily sourced from animal products, need special consideration. A deeper understanding of these risks and how to manage them is crucial for long-term health.

Common Nutrient Deficiencies in Vegetarians

Vegetarians, particularly vegans who exclude all animal products, are susceptible to deficiencies in several key vitamins and minerals. The bioavailability of nutrients from plant sources is often lower, and some nutrients are simply not present in plants.

Vitamin B12 Deficiency

Vitamin B12 is essential for neurological function and blood cell formation. Since it is found naturally only in animal products, vegetarians, especially vegans, are at high risk of deficiency without supplementation or fortified foods.

Symptoms of B12 deficiency can include:

Unusual fatigue and weakness
Tingling or numbness in the hands and feet
Difficulty with balance
Poor cognitive function
Megaloblastic anemia

Iron Deficiency and Anemia

While plant-based foods contain iron, it is in a form called non-heme iron, which is less easily absorbed by the body than the heme iron found in meat. Vegetarians often consume enough iron but may still develop deficiency due to lower absorption rates.

Signs of iron deficiency include:

Fatigue and a general lack of energy
Pale skin
Shortness of breath
Brittle nails and hair
Headaches and dizziness

Calcium and Vitamin D Insufficiency

Calcium is critical for bone health, and dairy products are a primary source for many. Vegans, in particular, may have lower calcium intake, which can negatively impact bone mineral density over time. Vitamin D, which aids calcium absorption, is also a concern for those with limited sun exposure or those who avoid fortified animal products like milk.

Potential issues from low calcium and vitamin D:

Lower bone mineral density, increasing fracture risk
Osteoporosis in later life
Rickets in children
Muscle cramps and spasms

Zinc Deficiency

Zinc is important for immune function, wound healing, and growth. The phytates present in many plant foods, such as legumes and whole grains, can inhibit its absorption. Studies show many vegetarians and especially vegans have lower serum zinc levels than meat-eaters.

Possible symptoms of zinc deficiency include:

Impaired immune function and increased infections
Hair loss and skin lesions
Poor appetite
Delayed wound healing

Omega-3 Fatty Acid Imbalance

Omega-3 fatty acids, particularly EPA and DHA, are crucial for brain and heart health. The best dietary source is fatty fish. While vegetarians can get ALA from plant sources like flaxseed and walnuts, the body's conversion to EPA and DHA is inefficient.

Potential consequences of low omega-3s:

Poorer cognitive function
Increased cardiovascular risk factors
Issues with vision and brain development, especially in infants

Comparison of Key Nutrient Concerns by Diet Type


Nutrient	Omnivore Diet	Lacto-Ovo Vegetarian Diet	Vegan Diet
Vitamin B12	Easily obtained from meat, dairy, eggs.	Obtained from dairy and eggs; supplementation is recommended for many.	Requires supplementation or fortified foods; plant foods are devoid of B12.
Iron	Easily absorbed (heme iron) from red meat; non-heme iron also present.	Less bioavailable (non-heme iron) from plants; intake may be adequate but absorption is a concern.	Same as vegetarians, with risk amplified by high phytate intake from grains and legumes.
Calcium	Ample source from dairy products.	Good source from dairy products.	Intake often lower; needs to focus on fortified alternatives and low-oxalate greens.
Vitamin D	Some sources from fatty fish, eggs, fortified milk.	Some sources from eggs and fortified dairy.	Often low; relies heavily on sunlight exposure and fortified foods or supplements.
Zinc	Readily absorbed from meat.	Absorption inhibited by phytates in plant foods.	Absorption most inhibited due to high phytate content; supplementation often recommended.
Omega-3s	Best source of EPA and DHA from fish.	Relies on ALA from plant sources, inefficient conversion to EPA/DHA.	Same as vegetarians; relies on ALA conversion or algae-based supplements.

Mitigating Nutritional Risks for Vegetarians

To prevent deficiencies, vegetarians must be proactive in their dietary planning and supplementation. A balanced approach ensures a vegetarian diet remains a healthy choice.

Here's how to manage these risks:

Supplementation: Regular vitamin B12 supplementation is essential for all vegetarians and vegans, regardless of diet duration. Supplements for vitamin D, iodine, and zinc may also be necessary, especially for vegans or those in high-risk groups. Algae-based supplements can provide EPA and DHA.
Fortified Foods: Incorporate foods fortified with key nutrients, such as fortified plant milks (with calcium and vitamin D), fortified breakfast cereals, and nutritional yeast.
Enhance Iron Absorption: Combine iron-rich plant foods (lentils, dark leafy greens) with vitamin C sources (bell peppers, oranges) to enhance absorption. Avoid drinking tea or coffee during meals, as tannins can inhibit iron absorption. Soaking and sprouting legumes can also reduce absorption inhibitors.
Focus on Bioavailable Plant Sources: Choose calcium-rich, low-oxalate greens like kale and broccoli over high-oxalate spinach. Opt for calcium-set tofu.
Consult a Professional: A registered dietitian can provide personalized guidance to ensure all nutritional needs are met, especially for pregnant women, children, and athletes.

Conclusion

While a vegetarian diet offers many health benefits, including a lower risk of certain chronic diseases, it is not without its nutritional challenges. The primary risks involve potential deficiencies in vitamin B12, iron, calcium, vitamin D, zinc, and omega-3 fatty acids. These issues stem from the absence of animal-based food sources and the lower bioavailability of some nutrients in plant foods. However, with careful planning, dietary fortification, and strategic supplementation, these risks can be effectively managed. A well-designed vegetarian diet can be nutritionally adequate and support optimal health at all stages of life, proving that a meat-free lifestyle does not have to be a suffering one. For more information on health considerations for a vegetarian diet, review the guidance from Harvard Health.

Frequently Asked Questions

The most common deficiency is Vitamin B12, as it is found naturally only in animal products. Without supplementation or fortified foods, vegetarians, and especially vegans, are at high risk of deficiency.

Vegetarians are at higher risk because the iron in plant foods (non-heme iron) is less bioavailable than the iron in meat (heme iron). Absorption can be further inhibited by phytates in grains and legumes.

While protein quality and digestibility are considered by some, vegetarians can generally meet their protein needs by eating a variety of plant-based sources like legumes, nuts, and whole grains. Vegans may need slightly more protein per pound of body weight to compensate for differences.

To get enough calcium, vegetarians can consume dairy products (if lacto-ovo), fortified plant milks, low-oxalate leafy greens like kale, fortified cereals, and calcium-set tofu.

Neurological symptoms can include tingling or numbness in the fingers and toes, muscle weakness, problems with walking and balance, and poor cognitive function.

Some studies have shown that vegetarians and especially vegans may have lower bone mineral density and higher fracture rates than omnivores, which is often linked to lower intake of calcium and vitamin D.

Yes, supplementation is often recommended, especially for vitamin B12, and potentially for vitamin D, iodine, and zinc, particularly for vegans or those who cannot meet their needs through fortified foods.

The biggest risk is multiple micronutrient deficiencies, which can undermine the health benefits of a plant-based diet and lead to serious long-term health issues like anemia, neurological damage, and poor bone health.