Heme Iron vs. Non-Heme Iron
Not getting enough of this nutrient will cause extreme fatigue and lightheadedness—luckily, most people in the U.S. are not deficient. It is best known for helping to keep our red blood cells healthy (dead giveaway right?).
Yes, we are referring to iron!
What Is Iron & Why Do We Care
Iron is an important mineral that is needed for growth and development. It combines with protein to form hemoglobin, which is found in red blood cells.
Hemoglobin gives red blood cells their red color and carries oxygen from the lungs to every cell in the body. Without enough iron, less oxygen is carried to your tissues, which deprives them of energy (oxygen is needed to produce energy) and leads to fatigue.
Iron has many important functions in the body:
- Helps with brain development & growth in children
- Needed for normal production and function of certain types of cells
- Boosts resistance to infection
- Needed to make some hormones
- Makes up myoglobin (a protein that carries and stores oxygen in muscle tissue)
How Much Iron Do We Need?
According to the National Institutes of Health (NIH), the amount of iron you need each day depends on your age, gender, and whether you eat a plant-based diet (probably most people reading this!).
NIH states that “...vegetarians who do not eat meat, poultry, or seafood need almost twice as much iron listed because the body doesn’t absorb non-heme iron in plant foods as well as heme iron in animal foods.”
We disagree. There are lots of plant foods that are rich in non-heme iron. Eating a variety of these foods every day means that we are easily able to meet our daily iron needs.
The Recommended Dietary Allowance (RDA) for iron is:
- Adult Women 19-50 years: 18 mg
- Adult Men 19-50 years: 8 mg
- Adults 51 years & older: 8 mg
You may be wondering why adult women need higher amounts of iron. This is because of the loss of blood during menstruation. Adult woman 51 years and older need less iron, assuming that they have reached menopause and no longer menstruate.
- RDA is the average amount of a nutrient that you should eat per day to maintain health (for nearly all healthy people).
- Please note that these amounts are listed in milligrams (mg) per day.
Sources of Iron
Iron found in food comes in two forms:
Heme iron is only found in muscles and blood, hence why it is only in animal foods. Food that contain heme iron include meat, poultry, and seafood. About 40% of the iron found in animal foods is heme iron and the rest, about 60%, is non-heme iron.
Non-heme iron is found in plant foods like whole grains, nuts, seeds, legumes, and leafy greens. Non-heme iron is also found in animal foods (animals eat plant foods that contain non-heme iron) and iron-fortified foods.
Sources of heme iron:
- Oysters, clams, mussels
- Beef or chicken liver
- Canned sardines or tuna
Sources of non-heme iron:
- Dark leafy greens like spinach & kale
- Potatoes with skin
- Seeds like chia seeds*
- Some dried fruits like raisins
- Fortified breakfast cereals
- Enriched rice or bread
- Cooking in a Cast Iron Skillet
*These plant-based sources of iron are found in our Overnight Sprouted Chia Puddings! Try the Chocolate Goji Berry flavor, which give you 40% of the iron that you need every day!
Problems with Iron Absorption
It’s not how much iron you consume, but how well you absorb it.
Heme iron is better absorbed by the body (about 15-35%) than non-heme iron (about 2-20%). BUT, plant-based eaters can still meet their daily iron needs by eating plenty of non-heme rich plant foods, like dark leafy greens, whole grains, legumes, dried fruits, nuts, and seeds.
It is good to know what enhances non-heme iron absorption and what takes away from it
Improves absorption of non-heme iron:
Eating vitamin C at the same meal. Many vegetables that are high in iron, like broccoli and bok choy, also contain high amounts of vitamin C, which means that the iron in these foods is well absorbed.
Interferes with absorption of non-heme iron:
- Large amounts of calcium, such as calcium rich foods or calcium supplements.
- Plant substances like phytates (found in grains, legumes, nuts, and seeds) & tannins (found in tea, coffee, wine). Sprouting plant-based foods can significantly reduce their phytate levels, which means better nutrient absorption!
Issues with too Much Heme Iron
The human body is able to naturally regulate how much non-heme iron that we absorb from plant sources, which helps to prevent our bodies from being overloaded with too much iron.
However, heme iron is a different story. Heme iron is easily absorbed, but not easily gotten rid of. In fact, the human body actually has no mechanism to excrete excess iron once it is absorbed.
This could mean trouble if we get too much iron in our system. For example, excess iron is stored in our organs, with the majority being put in our liver, heart, and pancreas. Too much iron in our organs could lead to damage and disease—eventually leading to life-threatening conditions like liver disease, heart problems, diabetes, and certain types of cancers.
This may be why studies have linked increased risk of death, heart risk, and cancer with the consumption of red meat.
Benefits of Non-Heme Iron
- Found in antioxidant-rich plant foods that have been shown to have a protective effect against inflammation and chronic diseases.
- Able to meet iron needs without detrimental risk to health (our bodies can control the absorption of non-heme iron from plant sources).
- Way better for the environment! According to a recent analysis, avoiding meat and dairy products is the single biggest way to reduce your environmental impact on the planet.
How Will I Know if I am Deficient?
Iron deficiency affects about 4-5 million Americans yearly. A lack of iron is called iron-deficiency anemia. It is the most common nutritional deficiency worldwide and affects all ages, including children and adults.
Symptoms of iron deficiency anemia: GI upset, weakness, tiredness, lack of energy, decreased ability to fight off germs and infections, issues with controlling body temperature, and problems with concentration and memory.
How to know for sure:
Iron is stored in the body as ferritin and is transported throughout the body by transferrin (a protein in blood that binds to iron).
If you think you are deficient in iron, you can have your doctor check your blood levels of both ferritin and transferrin.
How Can Vegans & Vegetarians Avoid Becoming Deficient?
The good news is that with a little bit of planning, vegans and vegetarians can easily get enough iron from their diet!
Here's how to get enough iron on a plant-based diet:
Eat a wide variety iron-rich plant foods every day.
Good plant sources of iron include lentils, chickpeas, beans, tofu, cashews, chia seeds, hemp seeds, pumpkin seeds, kale, dried apricots and figs, raisins, quinoa, and fortified breakfast cereal.
Combine non-heme iron and vitamin C.
Eating food combinations like beans and tomato sauce or stir-fried tofu and broccoli result in generous levels of iron absorption.
Avoid drinking tea or coffee with meals.
Tannins found in tea and coffee can significantly reduce iron absorption by up to 39% when drinking coffee with meals and by 64% when drinking tea.
Avoid eating calcium-rich foods and taking calcium supplements close to meals containing iron.
Calcium also reduces iron absorption. Calcium supplements should be taken several hours before eating a meal that is high in iron.
The Deal with Iron Supplements
It is not recommended to take an iron supplement unless your doctor has diagnosed you with iron-deficiency anemia. Check with your doctor to make sure that iron supplement is right for you.
When it comes to iron supplements, you can usually get away with taking a multivitamin because they are typically fortified with 100% of the RDA for women (18 mg of iron). Make sure you don’t overdo it with the supplements though! Common side effects of taking too much iron include constipation and nausea.
You may have heard that vegans and vegetarians are unable to meet their iron needs with plant-based foods, but this is simply not the case! With a little bit of planning, it can be easy to get enough iron on a plant-based diet.
With a little bit of planning, it can be easy to get enough iron on a plant-based diet, all while avoiding the health risks of eating too much meat and helping to preserve life on our planet!
- “Iron.” The Nutrition Source, the President and Fellows of Harvard College, 2019, www.hsph.harvard.edu/nutrition source/iron/.“Iron.” The Vegan Society, 2020,
- https://www.vegansociety.com/resources/nutrition-and-health/nutrients/iron.Mangels, Reed. “Iron in the Vegan Diet.” The Vegetarian Resource Group, 2018, www.vrg.org/nut rition/iron.php.
- Morck TA, Lynch SR, Cook JD. Inhibition of food iron absorption by coffee. Am J Clin Nutr. 1983 Mar;37(3):416-20. doi: 10.1093/ajcn/37.3.416. PMID: 6402915.
- “Office of Dietary Supplements - Iron.” NIH Office of Dietary Supplements, U.S. Department of Health and Human Services, 2019, ods.od.nih.gov/factsheets/Iron-Consumer/.
- Yang, Lichen et al. “Non-Heme Iron Absorption and Utilization from Typical Whole Chinese Diets in Young Chinese Urban Men Measured by a Double-Labeled Stable Isotope Technique.” PloS one vol. 11,4 e0153885. 21 Apr. 2016, doi:10.1371/journal.pone.0153885