Tired, forgetful, and lack of appetite? If this describes you, it's possible that your daily iron intake is not being met. This article will delve into what iron is and why it's important to meet the daily iron requirement.
Furthermore, the article will list ways to meet the daily iron needs. It will also explain which foods contain iron and discuss the pros and cons of dietary supplements, and who needs them.
Key Points
- Iron is a naturally occurring chemical element. Essentially, iron can be found in almost all foods, but iron has different oxidation states (Fe2+ and Fe3+), which are less soluble and not well absorbed by the body. (8)
- As a trace element, it is vital not only for humans but also for bacteria, plants, and animals. Without iron, the metabolism of most organisms would not function. (8)
- More than two-thirds of the body's iron is bound in the blood pigment hemoglobin. Most of the iron plays a crucial functional role in the bone marrow or as iron-containing proteins and enzymes. Only a fraction of the iron (0.1%) is responsible for transport, and about 20% of the iron serves as a storage reserve. (5)
Daily Iron Requirement: What You Should Know
The following answers the most crucial questions about iron and daily iron intake.
What are the functions of iron in the body?
Iron is an essential trace element for the body. Iron is stored in red blood cells. With the help of iron, oxygen can be transported in the blood. Iron is also an indispensable component of cells and enzymes. Without iron, human metabolism would not function. (1)
An iron deficiency leads to anemia, which in turn leads to a weakened immune system. For the natural immune system and the body's metabolism to function, it's crucial to meet the daily iron requirement. But caution is needed because too much iron can have negative effects. (1)
How does the body absorb iron?
An average adult consumes 20 mg of iron daily. The exact amount varies due to diet. However, not all of what is consumed is utilized. As a general rule, only about 5% of the ingested iron is absorbed in the small intestine. This value depends on individual iron storage levels and is adjusted accordingly. (1)
Did you know that women can absorb iron 2 to 2.5 times better than men? Women lose up to 30 mg of iron through menstruation once a month. Even though they can absorb iron better, they still need a higher intake than men. (2)
In stomach acid, multivalent iron compounds ingested through food are chemically separated. A transport protein transports the iron into the intestinal mucosal cells, and then, bound to other proteins, it enters the blood. In the blood, the iron is again converted into trivalent iron and is transported as needed. (1)
What is the daily iron requirement for adults?
An average healthy adult needs 1 mg of iron per day. The recommended intake, at 10 to 15 mg per day, is much higher. This is because when calculating daily iron needs, iron losses should also be taken into account. (2)
The data below pertains to the daily reference values for iron for healthy adults. (4)
| Gender | Iron in mg per day |
|---|---|
| Women | 10 to 15 |
| Men | 10 |
Besides avoiding falling below the daily amount, it's also essential not to exceed the recommended daily dose of iron, as the excess iron cannot be naturally excreted.
In extreme cases, acute poisoning symptoms can occur, such as (8):
- Vomiting
- Diarrhea
- Fever
- Blood clotting disorders or kidney and liver damage
Additionally, prolonged excessive iron intake can lead to chronic iron overload. (8)
Which groups of people have an increased daily iron requirement?
Certain groups of people have higher iron needs:
- In general, women of childbearing age have an increased need for iron due to menstruation. Additionally, during pregnancy (30 mg) and breastfeeding (20 mg), there's a higher daily iron requirement. (4)
- During pregnancy, an additional 300 mg of iron is consumed overall. This iron is primarily needed for the healthy development of the fetus, as it cannot yet independently absorb nutrients in the womb. After birth, 0.5 mg of iron is transferred from the breastfeeding mother to the baby daily. (2)
- Especially high iron needs are seen in growing children and teenagers. Particularly in the first two years of life and during puberty, there's often an increased iron requirement. The increased need during rapid growth, however, is often neglected. (5)
- Athletes also belong to the risk group for iron deficiency. Due to their physical performance, they often have a restricted diet or frequently suffer from mild inflammations and bleeding caused by training. (3)
- Just as with menstrual bleeding, other types of bleeding also result in iron loss. During a voluntary blood draw, naturally, much more iron is lost than through menstruation. Compared to menstruation (25 to 60 ml of blood per month with an iron content of 2.5-30 mg), blood donation (500 ml of blood with 242 mg ±17 mg of iron) results in a much higher loss of iron. (7)
Drawing blood results in a significant loss of iron. It's essential to compensate for this loss. (Image source: Michelle Gordon / pixabay)
Vegans and vegetarians, on the other hand, have the same daily iron requirement as average adults.
Iron Intake for Vegans and Vegetarians
While vegans and vegetarians have the same iron needs as omnivores, the type of iron they predominantly consume is different. Iron in plant-based foods is called non-heme iron, while iron in animal products is referred to as heme iron. Non-heme iron is not absorbed by the body as efficiently as heme iron. Consequently, vegetarians and especially vegans must be mindful of their iron intake to ensure they meet their daily needs. (6)
Best Sources of Iron
Regardless of dietary preference, here are sources of iron from both animal and plant-based foods:
- Animal-based sources (heme iron): Red meats, poultry, fish, liver, and oysters.
- Plant-based sources (non-heme iron): Lentils, chickpeas, beans, tofu, cashews, quinoa, fortified cereals, spinach, and pumpkin seeds.
It's worth noting that combining vitamin C-rich foods with non-heme iron sources can enhance the absorption of iron. So, consuming citrus fruits, strawberries, or bell peppers with iron-rich plant foods can be beneficial. (9)
Dietary Supplements: Pros and Cons
Iron supplements can be a viable option for those who have difficulty meeting their daily iron needs through food alone. However, they come with their own set of considerations:
- Pros: Quick way to boost iron levels, especially useful for those with iron-deficiency anemia or during pregnancy.
- Cons: Can cause gastrointestinal discomfort, constipation, or other side effects. Risk of overdose if not taken as directed.
It's essential to consult with a healthcare professional before starting any supplementation. (10)
Conclusion
Iron plays a pivotal role in various bodily functions, from oxygen transport to enzyme activity. Ensuring an adequate daily iron intake is essential for maintaining good health. Whether you get your iron from food or supplements, being aware of your needs and monitoring your intake can help prevent potential complications arising from deficiency or excess.
References:
- Iron Metabolism. World of Molecules. 2021.
- Iron Requirements in Pregnancy and Strategies to Meet Them. US National Library of Medicine. 2000.
- Iron Deficiency in Athletes. The Training Room. 2019.
- Iron. National Institutes of Health. 2021.
- Iron needs of babies and children. Stanford Children's Health. 2020.
- Iron in the Vegan Diet. The Vegetarian Resource Group. 2020.
- Iron and Blood Donation. American Red Cross. 2022.
- Iron Poisoning. Healthline. 2019.
- Boosting Iron Absorption: A Guide to for Low Iron Levels. Cleveland Clinic. 2021.
- Iron Supplements: Benefits, Side Effects, and Dosage. Verywell Fit. 2021.
Daily Iron Requirement: What You Need to Know
The following addresses the essential questions about iron and daily iron intake.
What functions does iron have in the body?
Iron is a vital trace element for the body. It is stored in red blood cells. With the help of iron, oxygen can be transported in the blood. Iron is also an indispensable component of cells and enzymes. Without iron, human metabolism would not function at all. (1)
An iron deficiency leads to anemia, which in turn results in a weakened immune system. For the natural immune system and the body's metabolism to function, it's crucial to cover the daily iron requirement. However, one must be cautious because an excess of iron can have adverse effects. (1)
When donating blood, you lose a significant amount of iron. One should consider compensating for this loss. (Image source: Michelle Gordon / pixabay)
On the other hand, vegans and vegetarians have the same daily requirement as regular adults. It is only more challenging for them to meet the daily dose, as many iron-rich sources are absent for them. (2)
What is the daily iron requirement for children?
The following data represents reference values, which can vary depending on the situation. (4)
| Age | m | w |
|---|---|---|
| Infants through breastfeeding | 0.5 mg | 0.5 mg |
| 1-7 | 8 mg | 8 mg |
| 7-10 | 10 mg | 10 mg |
| 10-19 | 12 mg | 15 mg |
Children and adolescents have different iron needs in various age groups. In principle, it can be said that children and adolescents in the growth phase require more iron. Both genders have the same iron needs until the onset of menstruation in girls. Because of the period, they lose iron monthly, which is the reason for their increased iron requirement.
What are the consequences of iron deficiency?
Iron deficiency is probably the most widespread deficiency symptom. Approximately 10% of women and 3% of men in Germany suffer from iron deficiency. The main reason for this is unbalanced nutrition. (2) Another relevant reason for iron deficiency is chronic bleeding. (9)
Iron deficiency is divided into three stages. (5)
- First, the iron reserves are depleted. The patient shows no symptoms. At this stage, iron deficiency can easily be remedied by increasing iron intake.
- In the second stage (latent iron deficiency), the body reacts to the lack of iron. It is evident as there is not enough iron available for hemoglobin synthesis.
- In the third stage (manifest iron deficiency), the hemoglobin concentration decreases.
Typical symptoms are exhaustion, shortness of breath, headaches, loss of appetite, concentration disorders, pale skin, inflammations in the corners of the mouth, tongue inflammation, swallowing difficulties, hair loss, brittle fingernails, and dry skin. (6)
In addition, iron deficiency manifests as poor body temperature regulation and an increased risk of infection due to a weakened immune system. (7) Not all symptoms always appear, and depending on the degree of deficiency, the manifestations of the disease can vary in intensity.
What are the ways to meet the daily iron requirement?
There are two ways to meet the iron requirement: either through supplements or by consuming a balanced and healthy diet. The following section answers the most important questions on this topic.
How can I meet my daily iron needs through food?
Divalent iron is easier for the body to absorb than iron from vegetables and fruits, as the latter is trivalent. In general, polyvalent compounds are more difficult for the body to access since they must first be broken down, which requires additional energy. (1)
The best sources of iron are meat and seafood.
The table below lists some animal products with high iron content. (2)
| Food | Average Iron Content per 100 g |
|---|---|
| Pork liver | 18 mg |
| Liver sausage | 5.3 mg |
| Beef | 2.4 mg |
| Chicken egg | 2 mg |
| Mackerel | 1.2 mg |
| Turkey breast | 1 mg |
| Pork | 1 mg |
| Cow's milk | 59 μg |
Moreover, there are certain substances that either promote or inhibit the chemical reactions involved in iron absorption. Inhibitory foods include wheat bran, black tea, and soy products. Not only food but also medicines like aspirin or antacids can inhibit iron absorption. On the other hand, vitamin C and citric acid promote iron absorption. (6)
How can I meet my daily iron needs with a vegetarian or vegan diet?
In vegetarian and vegan diets, most of the iron absorbed is trivalent. Trivalent iron is absorbed by the body two to three times less effectively than elemental and divalent iron. (6)
In vegetarian and vegan diets, many rich sources of iron are excluded. However, this doesn't mean that it's impossible to meet iron requirements with other foods and maintain a balanced, healthy diet.
To facilitate iron intake for our body, it's essential to consume foods that promote iron absorption and avoid inhibitory ones. Promoting means that trivalent iron gets split so that the body can absorb the iron more efficiently. (5)
In the following table, you'll find some vegetarian foods and their iron content. (2)
| Food | Average Iron Content per 100 g |
|---|---|
| Spinach | 3.8 mg |
| Black salsify | 3.3 mg |
| Corn salad | 2.0 mg |
| Rye whole grain bread | 2 mg |
| Wheat mixed bread | 1.7 mg |
| Boiled potatoes | 930 μg |
| Red beet | 857 μg |
| Boiled pasta | 800 μg |
| Wheat bread | 738 μg |
| Apple | 248 μg |
Iron is essentially found in almost all foods. The table above is intended to serve only as a reference. When adopting such a lifestyle, it's essential to delve deeply into the topic of nutrition and create a balanced dietary plan.
When should one turn to supplements or preparations to meet the iron requirement?
People who have a genetic predisposition to iron deficiency or pregnant women can use iron supplements to counteract the deficiency. Healthy individuals who suffer slightly from iron deficiency should first try to improve the body's iron levels through a modified diet.
Iron supplements can never replace a healthy diet; they can only remedy a deficiency in the short term.
Additional iron intake can cause inflammation and infections. In the case of pre-existing conditions, additional iron can also act as poison. It's therefore advisable to consult a doctor and have a blood test before taking extra iron supplements. (1)
How does the body absorb iron?
Iron preparations and iron supplements are used to artificially increase iron levels. (Image sources: Michael Longmire / unsplash)
The highest recommended daily amount of iron through dietary supplements is currently 5 mg, which is approximately 50% of the daily reference amount (2). It is advisable to discontinue the supplements and continue with a healthy diet as soon as the iron deficiency is rectified.
Which supplements are particularly suitable for covering the daily iron requirement?
There are various types of supplements to increase the iron content in the body.
- Iron tablet
- Iron powder
- Iron drops
- Iron tonic
In general, it depends on personal preference on how one would like to take the supplement. All variants have the same effect, and price does not play a significant role in their efficacy. How well you absorb the iron depends on your body and whether you consume inhibiting/promoting substances along with the iron.
Conclusion
The topic of iron in food is relevant for everyone. Iron is responsible for the most important metabolic processes in our body. Increased lethargy and fatigue may indicate that the body's iron stores are not being met. Especially women during their menstrual cycle and children/adolescents in their growth phase suffer from an increased iron requirement.
Generally, the iron intake from an average diet is completely sufficient to cover the daily iron balance. However, there are special cases where it is advantageous to use supplements, such as during pregnancy, growth phases, or due to illness. Even while taking supplements, one should always focus on a healthy, balanced diet. Iron supplements can be toxic and cause undesirable side effects. Therefore, intake should always be discussed with a doctor in advance.
References (9)
- Saller R, Römer-Lüthi Ch, Brignoli R, Meier R: Iron - a double-edged sword? Systematic review of the clinical significance of an essential trace element. Schweiz Z Ganzheitsmed 2007 Source
- A. Domke, R. Groflklaus, B. Niemann, H. Przyrembel, K. Richter, E. Schmidt, A. Weiflenborn, B. Wörner, R. Ziegenhagen: Use of minerals in foods. Toxicological and nutritional physiological aspects. Part II. BfR 2004 Source
- Quadri, A & Gojanovic, Boris & Noack, P & Brunner-Agten, Saskia & Huber, Andreas. (2018). Iron deficiency in athletes - new recommendations for diagnosis and therapy. Swiss Sports & Exercise Medicine. 66. Source
- D-A-CH Reference values for nutrient recommendation 2015 Source
- S. Fritz. New and proven in the therapy of iron deficiency. A literature search. Medical University of Graz. 2019 Source
- F. Huber, U. Beise. Iron deficiency. Association mediX. 2018 Source
- C. Herster. Prevalence and effects of iron deficiency in connection with blood donations - a cross-sectional analysis. Medical University of Graz. 2019 Source
- Klaus Schümann, Thomas Ettle, Bernadett Szegner, Bernd Elsenhans, Noel W. Solomons On risks and benefits of iron supplementation recommendations for iron intake revisited Journal of Trace Elements in Medicine and Biology, Volume 21, Issue 3, 10 September 2007, Pages 147-168 Source
- Gasche, C & Evstatiev, Rayko & Haas, T & Kaser, A & Knoflach, P & Petritsch, W & Weiss, Guenter & Reinisch, W. (2011). Diagnosis and treatment of iron deficiency and anemia in chronic inflammatory bowel diseases. Consensus of the Austrian Working Group for CED. Journal of Gastroenterology. 49. 627-32. 10.1055/s-0031-1273324. Source
An average adult consumes 20 mg of iron daily. The exact amount varies depending on the diet. However, not everything consumed is used; on average, only about 5% of the iron taken is utilized in the small intestine. This value depends on the individual's iron storage and is adjusted accordingly. (1)
Did you know that women can metabolize iron 2 to 2.5 times better than men? Women lose up to 30 mg of iron monthly due to menstruation. Even though they metabolize iron more effectively, they still need a higher intake than men. (2)
Stomach acid separates multivalent iron compounds ingested from food through chemical processes. A transport protein carries the iron into the intestinal mucosal cells, from where it finally enters the blood bound to other proteins. In the blood, the iron is again converted into trivalent iron and transported as needed. (1)
What is the daily iron requirement for adults?
A healthy adult requires 1 mg of iron per day. The recommended intake, at 10 to 15 mg per day, is well above this figure. This is because the calculation of daily iron needs should also factor in iron losses. (2)
The data below represents daily reference values for iron for healthy adults. (4)
| Gender | Iron in mg per day |
|---|---|
| Women | 10 to 15 |
| Men | 10 |
Aside from ensuring not to fall below the daily amount, it's also crucial not to exceed the recommended daily dose of iron, as excess iron cannot be naturally excreted.
In extreme cases, acute symptoms of poisoning can occur, such as (8):
- Vomiting
- Diarrhea
- Fever
- Coagulation disorders or kidney and liver damage
Besides these poisoning symptoms, a long-term high iron intake can lead to chronic iron oversupply. (8)
Which groups of people have an increased daily requirement of iron?
Furthermore, certain groups of people have increased iron requirements:
- In general, women of childbearing age have an increased need for iron due to menstruation. Additionally, during pregnancy (30 mg) and breastfeeding (20 mg), there is an increased daily need for iron. (4)
- During pregnancy, an additional 300 mg of iron is consumed overall. This iron is primarily needed for the healthy development of the fetus, as it cannot independently absorb nutrients in the womb. After birth, 0.5 mg of iron is transferred from the nursing mother to the baby daily. (2)
- Children and teenagers during growth have a particularly high iron requirement. Especially in the first two years of life and during puberty, there's often an increased need for iron. This increased need is often neglected during rapid growth. (5)
- Athletes are also at risk of iron deficiency. Due to their physical performance, they often have restricted diets or frequently suffer from minor inflammations and bleeding caused by training. (3)
- Just as with menstrual bleeding, iron is also lost in other types of bleeding. During a voluntary blood draw, one naturally loses much more iron than through menstruation. With blood donation (500 ml of blood with 242 mg ±17 mg of iron), the iron loss compared to menstruation (25 to 60 ml of blood per month with an iron content of 2.5-30 mg) is much higher. (7)
