Which nutrients do vegetarians lack and how to get them?

January 3, 2026 •

4 min read

While a thoughtfully planned vegetarian diet can be healthful and nutritionally adequate, studies show that vegetarians and vegans may be at an increased risk for deficiencies in several key vitamins and minerals. This risk is heightened if the diet lacks diversity or is not properly supplemented.

Quick Summary

This article details the key nutrients that may be lacking in a vegetarian diet, including Vitamin B12, iron, calcium, and omega-3s. It also provides practical strategies for sourcing these essential vitamins and minerals from plant-based foods, fortified products, and supplements.

Key Points

Vitamin B12 is Critical: As it is not found reliably in plant-based foods, supplementation or fortified foods are essential for all vegetarians and vegans to prevent neurological issues.
Enhance Iron Absorption: The iron in plant foods is less bioavailable, so pairing iron-rich foods with Vitamin C sources (e.g., citrus) is a crucial strategy.
Prioritize Calcium Sources: Vegans need to seek out calcium-set tofu, fortified plant milks, and low-oxalate leafy greens to compensate for the absence of dairy.
Consider Omega-3 Supplements: Since the body's conversion of plant-based ALA to active EPA and DHA is inefficient, an algal oil supplement may be beneficial for heart and brain health.
Improve Zinc Bioavailability: Soaking, sprouting, and fermenting legumes and grains can help increase the absorption of zinc, which is vital for immune function.
Don't Overlook Vitamin D: Due to factors like location and skin pigmentation, relying solely on sun exposure for Vitamin D is unreliable; fortified foods and supplements are often necessary.

Common Nutrient Deficiencies for Vegetarians

For those following a vegetarian or vegan diet, obtaining adequate amounts of certain nutrients primarily found in animal products requires careful planning. While a diverse and whole-food-based diet goes a long way, some nutrients pose a particular challenge.

Vitamin B12

Vitamin B12 is essential for nerve function and red blood cell formation, and is synthesized by microorganisms, not plants. For this reason, plant-based foods are unreliable sources of active B12. As a result, deficiency rates are significantly higher among vegetarians and vegans, with some studies finding high prevalence depending on age and life stage. The body can store B12 for several years, which means symptoms of deficiency can be slow to appear, masking the problem until serious health issues arise, including neurological damage.

Iron

Iron is crucial for oxygen transport, but the non-heme iron found in plants is less bioavailable than the heme iron from animal sources. Although many vegetarians consume high amounts of iron, lower bioavailability and inhibiting compounds like phytates mean lower iron stores (measured by ferritin levels) are common. Symptoms of iron deficiency anemia include fatigue, paleness, and shortness of breath.

Enhancing Non-Heme Iron Absorption: To counteract absorption inhibitors, it is vital to combine iron-rich plant foods with sources of Vitamin C. For example, squeeze lemon juice over spinach or add bell peppers to a lentil stew.

Calcium and Vitamin D

While lacto-ovo vegetarians consume dairy and eggs, vegans must find alternative sources for calcium and vitamin D. Calcium is critical for bone health, while Vitamin D aids its absorption. Insufficient calcium and Vitamin D can lead to higher fracture risk, particularly in vegans.

Calcium Sources: Fortified plant milks, calcium-set tofu, collard greens, kale, and broccoli are good sources. Note that some leafy greens like spinach contain high levels of oxalates, which can inhibit calcium absorption.
Vitamin D Sources: Sun exposure is a primary source, but many factors make it unreliable. Fortified foods like cereals and certain plant milks, along with supplements, are often necessary.

Omega-3 Fatty Acids

The three main omega-3 fatty acids are ALA, EPA, and DHA. ALA is readily available in plant sources like flaxseeds, chia seeds, and walnuts. However, the body's conversion of ALA to the crucial long-chain EPA and DHA is inefficient, especially in men. EPA and DHA are important for brain, heart, and eye health.

Zinc

Similar to iron, zinc absorption from plant sources is hindered by phytates. A zinc deficiency can affect immune function, wound healing, and growth. Cooking methods can help improve absorption.

Improving Zinc Absorption: Soaking, sprouting, or fermenting legumes, grains, and seeds can reduce phytate levels. Examples include sprouted grain bread and soaked lentils.

How to Address Potential Nutrient Shortfalls

A proactive approach to dietary planning is key for vegetarians to ensure adequate nutrient intake. This involves focusing on food choices and, for certain nutrients, considering supplementation.

Maximize Nutrient Intake Through Food Pairing

Iron & Vitamin C: Pair plant-based iron sources (e.g., lentils, beans) with vitamin C-rich foods (e.g., peppers, citrus) to enhance absorption.
Fats & Fat-Soluble Vitamins: Consume vitamins A, D, E, and K with healthy fats like nuts, seeds, or avocado to improve absorption.

Utilize Fortified Foods and Supplements

For nutrients like Vitamin B12, supplementation is often the most reliable strategy. Many cereals, plant milks, and nutritional yeast are fortified with B12, and supplements are widely available. Vegans may also benefit from an algal oil supplement to get direct EPA and DHA.

Nutrient Comparison: Vegetarian vs. Omnivore Diet


Nutrient	Primary Omnivore Sources	Primary Vegetarian Sources	Absorption/Bioavailability	Supplementation Considerations
Vitamin B12	Meat, dairy, eggs	Fortified foods, nutritional yeast	High (from animal sources)	Crucial for vegans and strongly recommended for vegetarians; supplementation or fortified foods are essential.
Iron	Red meat (heme iron)	Legumes, leafy greens, fortified cereals	Heme iron is more easily absorbed. Non-heme iron absorption is enhanced by Vitamin C.	Intake should be carefully planned, especially for women of childbearing age, by pairing with Vitamin C.
Calcium	Dairy products	Fortified plant milks, tofu, kale, broccoli	Generally high in dairy; absorption from plants varies based on oxalate content.	Vegans should choose fortified products and low-oxalate greens, and may require a supplement.
Vitamin D	Fatty fish, egg yolks, fortified dairy	Sun exposure, fortified products	Dependent on sunlight and diet. D3 from lanolin is often more bioavailable than D2.	Sunlight exposure is unreliable; supplementation is often recommended for all, especially vegetarians/vegans.
Omega-3s	Fatty fish (EPA/DHA)	Flaxseeds, walnuts, chia seeds (ALA)	High bioavailability in fish. ALA conversion to EPA/DHA is inefficient in humans.	Algal oil supplements provide highly bioavailable EPA and DHA, beneficial for vegans.
Zinc	Meat, fish	Legumes, nuts, seeds, whole grains	Generally higher in animal products; absorption from plants is inhibited by phytates.	Soaking and sprouting can improve bioavailability; intake should be monitored.

Conclusion

A balanced vegetarian diet can be highly beneficial for health, but it does require careful attention to certain nutrients. The primary concerns are Vitamin B12 and Omega-3s (EPA/DHA), which are best addressed through supplementation or fortified foods. Iron, calcium, and zinc, while available from plant sources, require mindful pairing and food preparation to maximize absorption. By understanding these potential shortfalls and adopting proactive dietary habits, vegetarians can ensure they receive all the essential nutrients for long-term health and wellbeing. For further guidance, consulting with a registered dietitian or consulting authoritative sources like the NIH Office of Dietary Supplements can be beneficial.

Frequently Asked Questions

No, a vegetarian diet is not automatically deficient. With mindful planning, it can be nutritionally complete. However, the risk of deficiency is higher for certain nutrients, making planning and potentially supplementation essential.

While it is possible to get nutrients from food, supplementation is the most reliable way for vegetarians and vegans to ensure adequate intake of Vitamin B12. Supplements for Vitamin D and Omega-3s (algal oil) are also widely recommended.

To increase iron absorption, consume iron-rich plant foods like lentils, beans, and spinach alongside Vitamin C-rich foods such as citrus fruits, bell peppers, and broccoli.

The best plant-based sources of ALA are flaxseeds, chia seeds, and walnuts. For direct EPA and DHA, algal oil supplements are the most effective source for vegetarians and vegans.

Zinc absorption can be improved by soaking, sprouting, or fermenting legumes, seeds, and grains. This process reduces phytate levels, which naturally inhibit mineral absorption.

Many fortified foods, such as plant-based milks, cereals, and nutritional yeast, can provide reliable amounts of nutrients like B12, Calcium, and Vitamin D. Always check product labels to ensure they are adequately fortified.

Studies show that vegans, in particular, may have lower bone mineral density and higher fracture rates compared to omnivores, especially if calcium and vitamin D intake is inadequate. Ensuring proper intake of these nutrients is essential for bone health.