Iron and Vegetarian Diets

Iron is a mineral used by the body with various important functions. 70% of iron is found in hemoglobin, a protein in red blood cells that helps to transport oxygen throughout the body (1). Iron is also used to make hormones and support the immune system (1,2). When one's iron intake is low for a prolonged period, it can lead to iron deficiency anemia.

What are Possible Symptoms of Iron Deficiency?

With iron deficiency anemia, the red blood cells become smaller and carry less hemoglobin, resulting in less oxygen being transported throughout the body (2). Iron deficiency anemia is very common both globally and in the United States (3). Those at increased risk of iron deficiency include menstruating women, pregnant and postpartum women, breastfeeding women, children who drink more than 2-3 cups of cow's milk daily, those who have undergone major surgery or bariatric procedures, and those with gastrointestinal diseases (celiac disease, ulcerative colitis, etc.) (3). Vegetarians and vegans are also at higher risk of iron deficiency, especially if their diets do not contain iron-rich foods (3).

Possible symptoms of iron deficiency anemia include (4):

• Weakness

• Extreme fatigue

• Headache

• Lightheadedness or dizziness

• Confusion, difficulty concentrating

• Pale skin

• Brittle nails

• Cold hands and feet

• Weakened immune system

• Shortness of breath

• Loss of appetite

• Pica (eating non-food items such as ice or dirt)

If your symptoms suggest you may have iron deficiency anemia, be sure to see your doctor for an official diagnosis and treatment plan.

Iron's Two Forms: Heme and Non-Heme

Iron from is found in two forms: heme and non-heme. Animal sources contain both heme and non-heme iron. Plant sources and foods fortified with iron only contain non-heme iron (5).

Sources of heme iron (5):

• Organ meats

• Oysters, clams, mussels

• Beef

• Poultry

• Fish

Sources of non-heme iron (5):

• Legumes

• Tofu

• Dark chocolate (at least 45%)

• Spinach

• Nuts

• Seeds

• Fortified breakfast cereals

• Enriched rice or bread

Iron Absorption Promoters and Inhibitors

Vegetarians need to be mindful of their iron intake because heme iron is more readily absorbed by the body than non-heme iron (5). Iron absorption can be increased, however, by pairing iron food sources with vitamin C (2)! Spinach can be paired with strawberries, tofu with broccoli, fortified breakfast cereals with citrus, and legumes with tomatoes, just to name a few examples.

Although non-heme iron is not as readily absorbed by the body, vegetarians can pair iron food sources with vitamin C for increased absorption!

It is also important for vegetarians to be wary of iron absorption inhibitors. Large amounts of calcium, especially in supplement form, may inhibit iron absorption (5). Plan for calcium supplements and high-calcium foods to be consumed at different times of the day than iron supplements or high-iron foods (2).

Bran fiber, phytic acid, and tannins can also inhibit iron absorption (5). Phytic acid is found in whole grains, seeds, legumes, and some nuts — this is part of the reason why many of these vegetarian high-iron food sources are not absorbed as well (6). Tannins are found in tea and coffee, so vegetarians are advised to avoid these drinks or to have them between meals (6).

How Much Iron Do We Need?

Recommended Dietary Allowance (RDA): Daily Iron (2,5)

	14-18 years	19-50 years	51 + years
Males	11 mg	8 mg	8 mg
Females	15 mg	18 mg	8 mg
Pregnancy	27 mg	27 mg
Lactation	10 mg	9 mg

Due to the body's reduced absorption of non-heme iron, vegetarians should aim for an intake of about twice as much iron (2). Below are some tables that can give you an idea of how much iron can be found in the most common non-heme sources (7).

It is possible to get enough iron as a vegetarian! Include a variety of iron food sources throughout the day. Include vitamin C whenever you can for additional absorption!

References:

1. The Importance of Iron in Your Body. American Red Cross. https://www.redcrossblood.org/local-homepage/news/article/iron-in-blood.html. Published November 11, 2021. Accessed March 31, 2023.

2. Iron. NIH Office of Dietary Supplements. https://ods.od.nih.gov/factsheets/Iron-Consumer/. Published April 5, 2022. Accessed March 31, 2023.

3. Iron-Deficiency Anemia. American Society of Hematology. https://www.hematology.org/education/patients/anemia/iron-deficiency. Accessed April 4, 2023.

4. Iron deficiency anemia. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/syc-20355034. Published January 4, 2022. Accessed April 2, 2023.

5. Iron. Harvard T.H. Chan School of Public Health. https://www.hsph.harvard.edu/nutritionsource/iron/. Published March 7, 2023. Accessed April 2, 2023.

6. Are Anti-Nutrients Harmful? Harvard T.H. Chan School of Public Health. https://www.hsph.harvard.edu/nutritionsource/anti-nutrients/. Published February 2, 2023. Accessed April 3, 2023.

7. Food Sources of Iron. Dietary Guidelines for Americans. https://www.dietaryguidelines.gov/resources/2020-2025-dietary-guidelines-online-materials/food-sources-select-nutrients/food-1. Published 2019. Accessed April 4, 2023.