Iron: Are You At Risk For Deficiency?

Introduction

Did you know that iron deficiency is one of the most common nutritional deficiencies worldwide? It affects close to 30% of the world’s population, and primarily affects women and children (1).

Iron is a mineral required by the body for the formation of hemoglobin, which carries oxygen from the lungs to the body’s tissues and organs. When hemoglobin gets too low, the rest of the cells in your body may not get the oxygen they need to survive, which can make iron deficiency very serious. In addition to hemoglobin formation, iron also plays a role in supporting our immune system by aiding in the formation of immune cells, and also plays a role through its antimicrobial activity (2).

Here, we discuss why not all iron is made equally, factors that can enhance or inhibit absorption, why women and vegans are most at risk for deficiency, and how iron supplements can be useful if you're not getting enough iron through diet alone.

Heme vs. Non-Heme Iron

Iron exists in two dietary forms: heme iron and non-heme iron.

Heme iron is found exclusively in animal products such as red meat, poultry, and fish, and is more readily absorbed by our bodies. It constitutes about 40% of the iron in these foods, with the remaining 60% being non-heme iron (3). The absorption of heme iron by our bodies is pretty efficient, with an absorption rate ranging from 15% to 35% (4). This efficient absorption is one reason why people who consume animal products are less likely to experience iron deficiency.

Non-heme iron is present in plant-based foods such as legumes, grains, nuts, and leafy green vegetables. It is less bioavailable, meaning it is not easily absorbed by our bodies. The absorption of non-heme iron is much lower than heme iron, ranging from 2% to 20%, and is influenced by various dietary components (5). The presence of certain dietary compounds in plant foods can inhibit non-heme iron absorption, making it even more challenging for vegans or those who follow plant-based diets to obtain sufficient iron from diet alone. This is why it is actually a common misconception that spinach is a great source of iron. Only about 2% of iron from spinach is actually absorbed (6). This is fairly low, especially when the absorption of iron from meat ranges from 15-35% (7).

If you’re vegan or plant-based and are looking for an all-in-one vegan multivitamin with iron to support your plant-based lifestyle, shop the plant-based essentials here.

Enhancers of Iron Absorption

Vitamin C: Ascorbic acid, or vitamin C, is one of the most potent enhancers of non-heme iron absorption (8). Mixing vitamin C-rich foods such as citrus fruits, bell peppers, and tomatoes with iron-rich plant meals can significantly enhance iron absorption.

Read here for scientist-backed tips for following a well-balanced vegan or plant-based diet.

Inhibitors of Iron Absorption

Phytates: Phytates are found in legumes, grains, and seeds and can bind to non-heme iron and inhibit its absorption. While soaking, sprouting, or fermenting these foods can reduce phytate content and enhance iron bioavailability, the impact of phytates on iron absorption still remains a concern for those relying heavily on plant-based foods as an iron source.

Polyphenols: Found in high concentrations in tea, coffee, and red wine, polyphenols can significantly inhibit non-heme iron absorption. Some studies have shown reductions in absorption by as much as 90% when tea is consumed with an iron-rich meal (9). To mitigate this effect, it’s advisable to consume beverages high in polyphenols between meals rather than during them.

Oxalates: Oxalates are found in spinach, beet greens, and certain nuts, and can bind to non-heme iron and reduce its absorption. Oxalates are why spinach is not a great source of high iron as once was thought.

Calcium: Calcium competes with iron for absorption in the intestines and can inhibit the absorption of both heme and non-heme iron (10). This interaction is particularly relevant for anyone who consume calcium-rich foods or calcium supplements alongside iron-rich meals.

Iron Needs in Men and Women

Iron requirements vary significantly between men and women, mostly because of differences in blood loss and physiological demands.

Men generally require less iron than women, with a recommended dietary allowance (RDA) of 8 mg per day. The lower requirement is largely due to the absence of menstrual blood loss. As a result, iron deficiency is less common in men, though men who follow vegan and plant-based diets must still be mindful of their vegan iron intake, particularly because non-heme iron in plants has lower bioavailability.

Women of reproductive age have a higher RDA of 18 mg per day, primarily to compensate for iron losses during menstruation. This increased need places women at greater risk of iron deficiency, especially those following a vegan diet. Women who are plant-based or vegan should be particularly careful about their vegan iron intake and may benefit from regular blood tests to monitor their levels.

Common Symptoms of Iron Deficiency

Symptoms of iron deficiency include fatigue, weakness, pale skin, shortness of breath, dizziness, and headaches. These symptoms occur because iron deficiency impairs the body’s ability to produce enough hemoglobin, leading to reduced oxygen delivery to tissues (11). In more severe cases, iron deficiency can result in iron-deficiency anemia. Iron deficiency can have serious long-term consequences if left untreated.

Iron Supplementation 101

Supplementation should be considered if you are unable to meet your iron needs through diet alone, particularly those with higher requirements or those following plant-based or vegan diets.

There are various types of iron supplements, including iron bisglycinate, iron sulfate, and iron gluconate. Each form has a different absorption rate and potential side effects. Iron bisglycinate and iron gluconate are known for being gentle on the stomach and easily absorbed by the body, while iron sulfate, the cheapest form of iron on the market, may cause gastrointestinal side effects such as nausea, constipation, or diarrhea (12). To minimize these side effects, it is recommended to take iron supplements with food or start with a lower dose and gradually increase it if needed.

Vegan iron bisglycinate can be found in our all-in-one vegan multivitamin with iron, the plant-based essentials.

Ways to Maximize Your Iron Intake if Plant-Based

1. Include plant-based sources of vegan iron in your diet such as beans, tofu, seeds, nuts, and dark leafy greens.
2. Prioritize eating vitamin C-rich foods along iron rich plant foods. For example, you can add bell peppers to a tofu stir-fry.
3. Use cooking techniques to reduce phytate content such as soaking, sprouting, and fermenting to improve iron bioavailability.
4. Include a vegan multivitamin with iron such as the plant-based essentials in your diet to ensure you’re meeting your daily iron needs. Our all-in-one vegan multivitamin with iron can be shopped here

Conclusion

Iron is an essential nutrient that requires careful attention, especially for those following a vegan diet. Understanding the differences between heme and non-heme iron, the factors affecting iron absorption, and common symptoms of iron deficiency can help maintain adequate iron levels and prevent deficiency. For many, supplementation may be helpful to ensure optimal iron status. As always, it’s advisable to consult with a healthcare provider if you suspect you may be deficient.

References:

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2. Morrison KD, Reiss MB, Tanner TD, Gollott TR, Loots GG, Collette NM. The application of synthetic antibacterial minerals to combat topical infections: exploring a mouse model of MRSA infection. Sci Rep. 2024 Jan 19;14(1):1762. doi: 10.1038/s41598-024-52082-8. PMID: 38243067; PMCID: PMC10798972.
3. Skolmowska D, Głąbska D. Analysis of Heme and Non-Heme Iron Intake and Iron Dietary Sources in Adolescent Menstruating Females in a National Polish Sample. Nutrients. 2019 May 10;11(5):1049. doi: 10.3390/nu11051049. PMID: 31083370; PMCID: PMC6567869.
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7. Insel, PM, Turner RE, and Ross D. (2003). Nutrition. 3rd edition. Jones and Bartlett 
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9. Cook JD, Reddy MB, Hurrell RF. The effect of red and white wines on nonheme-iron absorption in humans. Am J Clin Nutr. 1995 Apr;61(4):800-4. doi: 10.1093/ajcn/61.4.800. PMID: 7702022.
10. Lönnerdal B. Calcium and iron absorption--mechanisms and public health relevance. Int J Vitam Nutr Res. 2010 Oct;80(4-5):293-9. doi: 10.1024/0300-9831/a000036. PMID: 21462112.
11. Warner MJ, Kamran MT. Iron Deficiency Anemia. [Updated 2023 Aug 7]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK448065/
12. Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-. Tolerability of different oral iron supplements: a systematic review. 2013.Available from: https://www.ncbi.nlm.nih.gov/books/NBK133172/