When you think of iron, maybe it brings back memories of chalky chewables or Popeye the Sailor’s spinach habits. But what else should be on your radar when it comes to your health and how much iron per day is needed when you're trying to increase it via your diet or with iron supplements? Let’s dive in.

Why is iron important?

Iron is a mineral naturally found in the environment, as well as in many foods. Iron plays many important roles in the body; for example, iron is an essential component of hemoglobin, a red blood cell protein that aids in carrying oxygen. Hemoglobin binds oxygen in the lungs and transports it to the body’s tissues and organs, where the oxygen is exchanged for carbon dioxide. This enables carbon dioxide – the waste product of cellular respiration – to be removed from the body.¹ When there is an adequate level of iron in the body, each hemoglobin molecule can bind up to four oxygen molecules to adequately meet the oxygen needs of the cells. This oxygen is used to create adenosine triphosphate, or ATP, which provides the cellular energy for many of the body’s biochemical processes.²Iron is also a component of myoglobin, a protein that specifically carries and stores oxygen in muscle tissues to provide oxygen for ATP synthesis and meet the oxygen demand of active muscles.¹

Iron’s importance doesn’t stop there. Healthy brain development and function is associated with having an adequate iron status throughout life, with particular importance in utero and during infancy when iron needs are higher.³ Having adequate iron supports neural plasticity and neurotransmitter synthesis, which both impact cognitive function and influences our social behaviors.³ Maintaining an adequate level during pregnancy, with a proper diet or from iron supplements for women, and then throughout infancy ensures neurological growth and development for success.

What is an iron deficiency?

Iron deficiency is a lack of iron in the blood, which affects more than four million Americans annually and is the most common nutrient deficiency worldwide.^1,3 It is typically associated with dietary patterns that are low in iron, malabsorptive disorders (such as cystic fibrosis and celiac disease), post-gastric surgery that alters the route of digestion, when there is an increased need (such as pregnancy), or after blood loss. Because malabsorption is a common cause of iron deficiency, it is usually seen in combination with other nutrient deficiencies.⁴ Most commonly, an iron deficiency is seen in children, menstruating or pregnant women, and individuals with a diet lacking in iron, such as those following a vegetarian or vegan diet.¹

Infants and young children are at higher risk for iron deficiency anemia due to their increased iron needs throughout their rapid periods of growth and development. Preterm and low-birthweight infants or infants whose mothers are iron deficient are at higher risk for deficiency as well. When infants begin consuming solid foods around age 6-9 months, an inadequate intake of iron through foods or a non-iron-fortified formula can lead to deficiency.⁴

Women of reproductive age have higher iron requirements and thus are at increased risk for being iron deficient. At least 10 percent of women have menorrhagia (abnormally heavy bleeding during menstruation).⁴ As a key indicator that iron supplements might be needed, menorrhagia might account for 30-40 percent of all cases of iron-deficiency anemia in women of reproductive age. Pregnant and lactating women are also at higher risk for being iron deficient because of the iron needs of both mother and fetus in utero or infant provided through breastmilk.⁴

Iron deficiency progresses in stages, with the mild form occurring when there is a decrease in stored iron, which is often due to low dietary iron or excessive blood loss. As it progresses and iron stores continue to be depleted, total red blood cell count begins to decline until it results in iron-deficiency anemia. Without enough iron and significant decreases in red blood cell volume, there aren’t enough red blood cells to properly oxygenate the body, which leads to fatigue, weakness, and decreased energy.¹ Other signs and symptoms of iron-deficiency anemia include confusion and loss of concentration, shortness of breath, tachycardia (rapid heartbeat), pale skin, sensitivity to cold, dizziness, and headache.^1,5If you experience these symptoms of iron deficiency, then consult with a health-care professional to evaluate your health with attention to your iron level and whether iron supplements are right for you.

Iron overload: How much iron is too much?

On the flipside, iron overload, and even iron toxicity, is typically rare because of the body’s ability to regulate iron absorption and maintain an optimal iron level. However, iron overload can occur when high-dose iron supplements are taken unnecessarily.

Some genetic conditions, such as hemochromatosis, can cause an excessive iron buildup in the body, leading to iron overload and toxicity. This can cause further consequences, such as liver cirrhosis or impaired pancreatic function, when it is not diagnosed or not managed effectively.⁴ Common symptoms of iron overload include constipation, nausea, vomiting, and abdominal pain.

Also, long-term use of an iron supplement containing 25 mg or more daily can impact zinc status and can cause gastrointestinal symptoms like constipation or nausea. For these reasons, consult with a health-care professional to determine whether you need iron and, if so, what the optimal amount is based on your lab results.^1,4

Iron needs

So, you’re probably wondering, “How much iron should I take daily?” The answer is, it depends. Stage of life, gender, and age are all factors that play a role in individual iron needs. The Recommended Daily Allowances (RDAs) for iron in the table below represent the average daily intake to meet nutrition requirements for almost all non-vegetarian healthy individuals.⁴ The RDAs for vegetarians are 1.8 times higher than for those who eat meat because of differences in iron’s bioavailability from plant-based foods.⁴ We’ll explore this a bit further below to compare different foods and sources of iron.

Age	Male	Female	Pregnancy	Lactation
Birth to 6 months	0.27 mg*	0.27 mg*
7-12 months	11 mg	11 mg
1-3 years	7 mg	7 mg
4-8 years	10 mg	10 mg
9-13 years	8 mg	8 mg
14-18 years	11 mg	15 mg	27 mg	10 mg
19-50 years	8 mg	18 mg	27 mg	9 mg
51+ years	8 mg	8 mg

*Adequate daily intake

The iron need of infants at age 7-12 months is significantly higher because of the rapid growth and development of children at this age.

There are different RDAs for iron, depending on age and gender. Females typically need more than males from puberty through childbearing years. What’s more, how much iron per day for a woman depends on life events. For example, a pregnant woman has a significantly higher iron need due to the growth of the fetus and the increased blood supply and circulation throughout pregnancy. As a woman goes through menopause, her iron need typically decreases because menstruation has ended, and iron is no longer being lost each month during menses. This can change, however, if a woman has another source of blood loss such as uterine fibroids.

Dietary sources of iron

Iron is a common nutrient found in a variety of foods, but is all iron created equal? The two forms of dietary iron are heme and nonheme iron. Hemoglobin in red blood cells contains heme iron, the form only found in animal-derived foods such as beef and poultry, and certain seafood. Heme iron provided by animal-derived foods is the best source of iron, as it’s absorbed and utilized by the body approximately twice as well as nonheme iron.⁶

Nonheme iron is found naturally in plant-derived foods, like leafy greens and beans, or is added to foods (fortified/enriched) like rice, breads, and breakfast cereals, making them good vegan sources of iron.⁵ The fiber and other phytonutrients in plants can bind to nonheme iron, which makes it less available for absorption in the body.⁶ However, pairing plant sources of nonheme iron with animal sources of heme iron can enhance iron’s absorption. In addition, consuming vitamin C – as a supplement or in foods like bell peppers, citrus fruits, or strawberries – along with iron-rich foods improves iron’s absorption to help you meet your iron needs.⁵ Individuals following a vegetarian or vegan diet have increased iron needs due to the lower bioavailability of nonheme iron in plant-based foods. But that doesn’t mean iron needs can’t be met! Looking into your dietary patterns can help to determine how much iron per day is coming from foods and when or if you should consider an iron supplement. Here are a few examples of heme iron- and nonheme iron-rich foods and their corresponding iron content per serving:⁵

Fortified cereals: 18 mg per cup
Oysters: 8 mg per 3 ounces
White beans: 8 mg per cup
Dark chocolate: 7 mg per 3 ounces
Lentils: 3 mg per ½ cup
Spinach: 3 mg per ½ cup cooked
Beef round steak: 2 mg per 3 ounces
Potato: 2 mg per 1 medium sized

Which types of iron supplements are the best?

If your iron need is increased or you have other factors impacting your iron status, like malabsorption or hereditary conditions, then iron supplements can be a healthy addition to your daily regimen. The world of nutritional supplements can be overwhelming with all the different types and forms on store shelves. Iron supplements can be sold as iron pills, dissolvable iron tablets, and even as gummies or oral sprays. Thorne opts for providing iron supplements in capsule form for multiple reasons. Capsules, unlike tablets, do not require binders, coatings, or other additives to maintain its shape. Capsules also break down easier in the body, making the iron more readily available for the body to digest and absorb, and helping answer the question, “How much iron per day am I truly getting from my supplement?”

Iron sulfate versus iron bisglycinate

When deciding on what iron supplements are best, pay attention to the chemical form the iron comes in. Chelated iron, such as the iron bisglycinate in Thorne’s iron supplements, is iron bound to two molecules of the amino acid glycine. This form improves absorption because the two molecules of glycine block dietary factors like fiber from interfering with absorption. Compared to commonly prescribed iron (ferrous) sulfate, iron bisglycinate is more soluble, which translates to better absorption, which in turn decreases gastrointestinal side effects like constipation and stomach upset.⁷

What does the science say about iron bisglycinate versus iron sulfate?

A study in 100 anemic patients compared 120 mg iron sulfate to 120-, 60-, and 30-mg doses of iron bisglycinate daily for one month. The 60-mg dose of iron bisglycinate for four weeks provided the best dose response in terms of elevating hemoglobin and serum ferritin (a protein that enhanced iron storage). The 120-mg dose of iron bisglycinate resulted in 50-percent fewer GI side effects compared to the same dose of iron sulfate.⁸A randomized, crossover study of the tolerability of iron bisglycinate versus iron sulfate found significantly more subjects preferred the bisglycinate form because it was less likely to cause GI upset.⁹

In a study of children ages 6-36 months who were fed 5 mg/kg body weight of iron bisglycinate or iron sulfate for 28 days, only the iron bisglycinate demonstrated significant increases in serum ferritin.¹⁰

Which iron supplement should you take?

Several of Thorne’s nutritional supplements contain iron bisglycinate – either as a single nutrient, like Iron Bisglycinate, or as part of a comprehensive blood-building formula like Advanced Iron Complex, which also includes B vitamin cofactors and vitamin C to optimize iron absorption.* Thorne’s Basic Prenatal is a daily multi-vitamin/mineral complex for women who are trying to conceive, are pregnant, or are nursing. It helps to replenish lower iron during pregnancy and support the baby’s healthy development.*

Because iron plays such an important role in the healthy function of red blood cells, measuring your blood health can provide an accurate picture of your overall health. Thorne‘s Biological Age Health Panel analyzes multiple blood biomarkers to provide insights on blood health, as well as total body and organ system health to enhance your overall wellness and longevity.

Want to learn more about iron’s role in the body and how best to supplement with iron? Then check out these other Take 5 Daily articles:

References

Harvard School of Public Health. Iron. HSPH.Harvard.edu. https://www.hsph.harvard.edu/nutritionsource/iron/ [Accessed September 12, 2022.]
Ada. Hemoglobin. Ada.com. Updated September 21, 2022. https://ada.com/biomarkers/hemoglobin/ [Accessed September 22, 2022.]
Ferreira A, Neves P, Gozzelino R. Multilevel impacts of iron in the brain: The cross talk between neurophysiological mechanisms, cognition, and social behavior. Pharmaceuticals (Basel) 2019;12(3):126. doi:10.3390/ph12030126
National Institutes of Health. Iron. ODS.od.NIH.gov. Updated April 5, 2022. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/ [Accessed September 12, 2022.]
Kohn J. Iron. EatRight.org. Published September 13, 2022. https://www.eatright.org/food/vitamins-and-supplements/types-of-vitamins-and-nutrients/iron [Accessed September 26, 2022.]
Ball J. What is iron and why do you need it? EatingWell.com Published October 6, 2021. https://www.eatingwell.com/article/7920421/what-is-iron-why-do-you-need-it/ [Accessed September 26, 2022.]
Christiansen S. The health benefits of chelated iron. Verywellhealth.com. Updated August 30, 2021. https://www.verywellhealth.com/chelated-iron-benefits-4684057 [Accessed September 26, 2022]
Pineda O, Ashmead HD, Perez JM, Lemus CP. Effectiveness of iron amino acid chelate on the treatment of iron deficiency anemia in adolescents. J Appl Nutr 1994;46:2-13.
Coplin M, Schuette S, Leichtmann G, Lashner B. Tolerability of iron: a comparison of bis-glycino iron II and ferrous sulfate. Clin Ther 1991;13:606-612.
Pineda O, Ashmead HD. Effectiveness of treatment of iron-deficiency anemia in infants and young children with ferrous bis-glycinate chelate. Nutrition 2001;17:381-384.

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