Key Minerals Most Likely to be Lacking in Vegetarian Diets

December 7, 2025 •

4 min read

According to a 2021 review, individuals on plant-based diets, especially vegans, often show lower intake and status of several key nutrients compared to meat-eaters. This makes it crucial to understand which minerals are most likely to be lacking in the diets of vegetarians and how to address these potential shortfalls through diet planning and supplementation.

Quick Summary

A vegetarian diet needs careful planning to ensure adequate intake of essential minerals like iron, zinc, calcium, and iodine. Factors like lower bioavailability and the absence of animal products increase the risk of deficiencies. Strategic food choices and, for some, supplementation are necessary to maintain optimal health.

Key Points

Iron absorption is less efficient: Plant-based iron (non-heme) is not absorbed as well as animal-based iron (heme), and its absorption is further inhibited by phytates and polyphenols.
Calcium intake can be lower: Vegans, in particular, may consume less calcium, and some plant sources contain oxalates that reduce its bioavailability.
Zinc absorption is reduced: The phytates found in many plant foods like legumes and grains decrease the body's ability to absorb zinc effectively.
Iodine sources are less common: Without dairy and seafood, vegetarians and vegans must rely on iodized salt, fortified foods, or supplements for adequate iodine, which is crucial for thyroid function.
Selenium levels depend on geography: The selenium content of plant foods varies with the soil, placing those in low-selenium regions at risk of deficiency.
Strategic pairing enhances absorption: Consuming vitamin C-rich foods with meals can significantly increase the absorption of non-heme iron.

Why Mineral Absorption Differs in Vegetarian Diets

One of the main reasons vegetarians need to be vigilant about their mineral intake is due to the presence of certain plant compounds that inhibit absorption. These 'antinutrients', such as phytates and oxalates, bind to minerals and prevent their uptake by the body. While some preparation methods, like soaking and sprouting grains, can reduce these inhibitors, they are still a significant factor to consider. Meat, on the other hand, contains 'heme' iron, which is absorbed more easily than the 'non-heme' iron found in plants.

Iron

Iron deficiency is a common concern, especially for vegetarian women. Non-heme iron from plants is less bioavailable, meaning the body absorbs less of it. This risk is compounded by the inhibiting effects of phytates in legumes and whole grains, and polyphenols in tea and coffee.

Plant-based sources: Excellent vegetarian sources include lentils, chickpeas, fortified cereals, spinach, and kidney beans.
Enhance absorption: Consuming vitamin C-rich foods like citrus fruits, bell peppers, and broccoli with iron-rich meals can dramatically increase absorption.

Calcium

With dairy products removed from a vegan diet, calcium intake is a key concern. Even some leafy greens, like spinach, contain oxalates that can interfere with calcium absorption. Adequate calcium intake is vital for bone health, and studies have shown lower bone mineral density in vegans.

Vegan sources: Good sources include fortified plant milks and yogurts, calcium-set tofu, kale, bok choy, and almonds.
Bioavailability: Calcium absorption from low-oxalate vegetables like kale is much higher than from high-oxalate options like spinach.

Zinc

Similar to iron, the zinc found in plant foods is less bioavailable due to phytic acid. Zinc is crucial for immune function, wound healing, and growth. Studies indicate that vegetarians and vegans tend to have lower serum zinc levels than omnivores.

Plant-based sources: Excellent sources include legumes (beans, lentils), nuts, seeds, and whole grains.
Absorption strategy: Soaking and sprouting can help reduce phytate content and improve absorption.

Iodine

Iodine is critical for thyroid function, which regulates metabolism. The main dietary sources for omnivores are dairy and seafood, making it a common shortfall in vegetarian diets, especially vegan ones. Many plant-based milk alternatives are not fortified, so checking labels is essential.

Primary sources: Iodized salt, fortified plant milks, and sea vegetables like nori and kelp.
Caution with seaweed: The iodine content in seaweed can vary dramatically, with some species containing excessive amounts.

Selenium

The selenium content of plants depends heavily on the mineral content of the soil, which varies geographically. In regions with low soil selenium, vegetarians and vegans may be at risk of inadequate intake. Selenium is important for antioxidant defense and thyroid health.

Plant-based sources: The content varies, but good sources include Brazil nuts, whole grains, and legumes.
Brazil nuts: A single Brazil nut can provide a significant portion of the daily selenium requirement, though content can vary.

Comparison of Mineral Bioavailability in Vegetarian vs. Omnivore Diets


Mineral	Primary Sources in Omnivore Diet	Bioavailability in Vegetarian Diet	Common Issues for Vegetarians
Iron	Red meat, poultry, fish	Lower (non-heme iron)	Inhibition by phytates and polyphenols; lower iron stores.
Calcium	Dairy products	Lower from some plant sources	Interference from oxalates and phytates; lower intake in vegans.
Zinc	Meat, dairy, eggs	Lower	Reduced absorption due to phytates in plant foods.
Iodine	Dairy, seafood	Potentially inadequate	Absence of main sources; variability in fortified products.
Selenium	Fish, meat, eggs	Variable	Dependent on soil content; lower intake in certain regions.

Supplementation and Diet Planning

While a well-planned vegetarian diet can provide adequate nutrition, supplementation may be necessary for certain minerals, particularly for vegans. For example, reliable sources of vitamin B12, often taken in conjunction with mineral supplements, are essential. It is prudent for vegetarians, especially those with more restrictive diets, to monitor their nutrient intake and consider blood tests to identify and address any deficiencies. Regular consultation with a healthcare provider or a registered dietitian is highly recommended to create a balanced dietary plan. For regions with low soil selenium, supplementing may be beneficial, though excessive intake from sources like seaweed can also be a risk.

Conclusion

While a vegetarian diet offers numerous health benefits, it requires careful consideration to ensure adequate mineral intake. The potential lack of certain minerals like iron, calcium, zinc, iodine, and selenium can be managed through strategic food pairing, careful food choices, and fortification. Understanding the lower bioavailability of plant-based minerals is key to preventing deficiencies. With proper planning and, when needed, supplementation, vegetarians can maintain optimal health and enjoy the benefits of their dietary choices. For more in-depth information on nutrition for plant-based diets, consider consulting resources from the National Institutes of Health.

Frequently Asked Questions

Iron from plant sources (non-heme iron) is less efficiently absorbed by the body compared to heme iron found in meat. Plant compounds like phytates and polyphenols further inhibit non-heme iron absorption.

While most vegetarians have adequate calcium intake, vegans must be more cautious as they don't consume dairy. Some plant-based calcium sources are also less bioavailable due to oxalates.

Zinc absorption can be enhanced by soaking and sprouting legumes, nuts, and seeds to reduce phytate content. Pairing these foods with protein-rich items can also help.

For vegetarians who do not consume dairy or seafood, reliable sources include using iodized salt, consuming fortified plant-based milks, or taking a supplement. Over-relying on seaweed can risk excessive intake.

Supplementation for selenium is most important for vegetarians living in regions with low-selenium soil, such as Central and Northern Europe. However, a single Brazil nut per day is also a potent source.

Yes, vegetarian children can be at higher risk for deficiencies in iron, zinc, and iodine, especially if their diets are not meticulously planned to ensure adequate intake of these minerals. Consulting a dietitian is often recommended.

Yes, proper food preparation methods like soaking, sprouting, and cooking grains and legumes can help to reduce the levels of phytates, which inhibit the absorption of minerals like iron and zinc.