Iron plays an important role in our body's metabolism and without it, we wouldn't be able to function properly. Iron deficiency is one of the most common deficiencies in the world. Therefore, I've created this guide about iron on a vegan diet for you. It will answer your questions about how much iron you need, how to get it from plants and what are the best plant-based iron sources.
What Is Iron?
Only 4-5 g of iron can be found in an adult human body. This may not seem like a lot but iron is actually a very essential component of the human body. Iron is a mineral and the central component of the proteins hemoglobin and myoglobin. Hemoglobin is the red blood pigment found in red blood cells. Myoglobin is a protein that can store oxygen.
Why Do I Need Iron?
Essentially, without iron our body wouldn't be able to function because it wouldn't have the energy it needs. Iron plays a key role in DNA synthesis and also the production of energy cells. Hemoglobin and myoglobin can store oxygen and transport it through our body and to our muscles.
Can I Get Iron From Plants?
YES! You can get plenty of iron from plants. However, iron from plant-based sources is different than iron from animal-based sources so there are a few things to keep in mind.
Before I go on with the differences, let me first explain to you the concept of bioavailability. Bioavailability describes how much of a nutrient or medicine is absorbed into the bloodstream. This is essential because the bloodstream connects all of our body's organs and can transport the nutrient or medicine to whereever it is needed. If a nutrient does not enter the bloodstream, it is useless to our body.
- Heme iron: Iron that is derived from animal-based sources such as meat, poultry or fish is called heme iron. It has a high bioavailability or absorption rate.
- Non-heme iron: Plant-based iron sources are referred to as non-heme iron. Non-heme iron has a lower bioavailability compared to heme iron.
In omnivore diets, the bioavailability of iron is approximately 14% to 18%. In contrast, from vegetarian/vegan diets, the bioavailabity is 5% to 12%. Because iron from plants has a lower bioavailability, the recommended daily intake for vegetarians and vegans is 1.8 times higher than for people with an omnivore diet. (data taken from here)
How Much Iron Do I Need?
How much iron you need depends highly on your age and gender. Up to the age of ~10, the iron requirements of men and women are the same. After that, females have higher iron requirements, especially during the reproductive age and while pregnant.
When determining how much of a nutrient we should consume, we usually take a look at the Recommended Dietary Allowance (RDA). This value describes the average daily intake that is needed to meet the nutrient requirements of most healthy individuals. There is also a Tolerable Upper Intake Level (UL) which is the maximum daily intake without causing harm to the body. For iron, it's 40-45 mg.
One organization that publishes these guidelines for adequate dietary intake is the Food and Nutrition Board (FNB). It's part of the U.S. National Academy of Sciences, Engineering and Medicine. You can find their full report on dietary reference intakes here. The German, Swiss and Austrian Nutrition Associations (DGE, SGE, ÖGE) have also published reference values for iron supply.
In the following table, I have added the recommended intake values from the FNB and DGE. It shows that there are slight differences. The numbers in brackets are simply multiplied by 1.8 and show the recommendations for vegetarians/vegans.
Recommendations for Iron Intake
|birth to 4 – 6 months||0.27 mg||0.5 mg||0.27 mg||0.5 mg|
|4 – 6 months to 12 months||11 mg||8 mg||11 mg||8 mg|
|14 to 18 years||11 mg||12 mg||15 mg||15 mg|
|19 to 50 years||8 (15) mg||10 (18) mg||18 (33) mg||15 (27) mg|
|51+ years||8 (15) mg||10 (18) mg||8 (15) mg||10 (18) mg|
|pregnancy||–||–||27 mg||30 mg|
|lactation||–||–||9 mg||20 mg|
As you can see, I have not included the values for the ages 1 to 13 years because there are quite a few nuances in between. Also, for breastfeeding women (lactation) the values show a significant difference. If you are pregnant, breastfeeding or have children, I encourage you consult a doctor that you trust.
What If I Don't Get Enough Iron?
If you body does not have enough iron, this is called an iron deficiency. Sometimes this stage doesn't cause any symptoms yet. However, it can lead to an iron deficiency anemia where the body cannot produce enough hemoglobin.
Iron deficiency is quite common around the world. It is believed that 5-10% of Europeans and even 20% of young women in Europe are iron deficient. Symptoms are tiredness, diziness, fatigue, headaches, brittle nails, hair loss, cracks in the sides of the mouth, lack of concentration or frequent infections.
What Are the Best Plant-Based Iron Sources?
Legumes, nuts, seeds, grains, dark green leafy vegetables and soy products are all good sources of plant-derived iron. If you follow a well balanced plant-based diet and eat a variety of these foods, you can get plenty of iron. The list below includes the best plant-based iron sources. The values are taken from the USDA nutrient database for standard reference.
- tofu, firm (100g): 2.6 mg
- tempeh (100g): 2.7 mg
- soy drink, fortified (100g): 1.9 mg
- lentils, raw (100g): 6.5 mg
- lentils, cooked (100g): 3.3 mg
- kidney beans, raw (100g): 6.7 mg
- kidney beans, cooked (100g): 2.9 mg
- split peas, raw (100g): 4.7 mg
- split peas, cooked (100g): 1.3 mg
- chickpeas, raw (100g): 4.3 mg
- chickpeas, cooked (100g): 2.9 mg
- black beans, raw (100g): 5 mg
- black beans, cooked (100g): 2.1 mg
- white beans, raw (100g): 10.4 mg
- white beans, cooked (100g): 3.7 mg
- hummus (100g): 2 mg
- almonds, almond butter (25g): 0.9 mg
- cashews (25g): 1.7 mg
- piostachios (25g): 1 mg
- pumpkin seeds (25g): 2.2 mg
- sunflower seeds (25g): 1.3 mg
- sesame seeds (25g): 3.6 mg
- tahini (25g): 2.2 mg
- oats (100g): 4.3 mg
- quinoa, cooked (100g): 1.5 mg
- brown rice, cooked (100g): 0.6 mg
- white rice, cooked (100g): 1.5 mg
- barley, cooked (100g): 1.3 mg
- spinach, cooked (100g): 3.6 mg
- asparagus, cooked (100g): 0.9 mg
- swiss chard, cooked (100g): 2.3 mg
- sun-dried tomatoes (100g): 9.1 mg
- brussels sprouts, cooked (100g): 1.2 mg
- broccoli, cooked (100g): 0.7 mg
- tomato puree (100g): 1.8 mg
- blackstrap molasses (20g): 0.9 mg
Here are a few ideas how you can combine these plants to create delicious, iron-packed meals:
How Can I Increase My Iron Intake?
As we have learned earlier, the bioavailability of iron highly depends on the source and plant-based iron generally has a lower bioavailability. However, there are a few things you can do and a few you should avoid to increase your iron intake.
Other vitamins, minerals and antioxidants that we consume may increase or hinder the absorption of iron. They are enhancers or inhibitors of iron absorption. Vitamin C increases the absorption of non-heme (plant-based) iron. It is found in citrus fruits such as lemons, oranges, limes or grapefruits, in other fruits such as kiwis and strawberries and also in vegetables such as sweet bell peppers, tomatoes, broccoli and also some green leafy vegetables.
Phytates (phytic acids) are anti-nutrients which means they interfere with the absorption of nutrients, in this case iron (and also other minerals). These phytic acids bind the minerals in our body so our body is no longer able to absorb and use them. Phytates can be found in grains, nuts and seeds but also vegetables and legumes. It is not very feasible to avoid these foods altogether. However, soaking/sprouting of nuts, seeds and legumes can reduce this effect and increase the iron absorption.
Additionally, black tea, some herbal teas and coffee have a negative effect on non-heme iron absorption so these drinks should be consumed before or after eating, but not during. In short, here's what you can do to increase your iron intake:
- Drink a glass of orange juice or add fruits/vegetables high in vitamin C to your meals.
- Soak and/or sprout nuts, seeds and legumes.
- Avoid drinking black tea, herbal teas and coffee directly with meals.
What Else Should I Keep in Mind?
There are certain groups of people called "high risk groups" who should pay careful attention to their iron intake. If you belong to one of them or care for one of them, it is best to consult a doctor. The high risk groups are:
- Women with heavy menstrual bleeding: 10% of women are believed to have heavy menstrual bleeding. Heavy menstrual bleeding might be responsible for iron deficiency anemia in women in the reproductive age due to the high blood and iron losses during menstruation. It can be up to 50 mg per period.
- Pregnant women: During pregnancy, more red blood cells are produced due to the rapid growth of the placenta and fetus. Therefore, pregnant women have a higher iron need. An iron deficiency during pregnancy might lead to premature birth, low birth weight and increased infant mortality.
- Infants/young children: Due to their rapid growth, infants and young children have higher iron requirements. Normally, infants are born with sufficient iron stores if they are not born preterm or with low birth-weight and the mother is not iron deficient. These iron stores plus the breast milk provide enough iron for the first couple of months.
At 6 to 9 months old, infants need to obtain adequate amounts of iron from solid food sources as breast milk is no longer sufficient.
- Athletes: Increased oxygen demands from higher activity leads to higher iron needs.
- Frequent blood donors: Because frequent blood donors loose a lot of iron with the blood, iron supplements might be needed to help replenish the iron stores.
Have you ever had your iron levels checked by a doctor? I vaguely remember I had an iron deficiency during my childhood/teens. I don't exactly remember how old I was but I know I had to take supplements which helped. I haven't checked recently but I'm planning to do a all-round check-up soon.
I really hope that this guide about iron on a vegan diet was helpful to you and would love to hear from you in the comments below! What mineral or vitamin would you like to learn about next?