How much iron should an 18 year old have?

December 4, 2025 •

3 min read

According to the National Institutes of Health, an 18-year-old female needs 15 milligrams (mg) of iron per day, while an 18-year-old male requires 11 mg. This significant difference in iron requirements is primarily due to the onset of menstruation in adolescent girls.

Quick Summary

The daily iron needs for an 18-year-old differ by gender, with females requiring more due to menstruation. Males need 11 mg per day, whereas females need 15 mg. Individual needs can vary based on factors like athletic activity and diet.

Key Points

Gender-Specific Needs: 18-year-old males need 11 mg of iron per day, while females need 15 mg.
Reason for Gender Difference: Females require more iron to compensate for menstrual blood loss.
Iron's Function: Iron is crucial for hemoglobin production, energy, and brain function during adolescent growth.
Dietary Sources: Excellent sources include lean red meat (heme iron) and lentils, spinach, and fortified cereals (non-heme iron).
Boost Absorption: Pair non-heme iron foods with vitamin C-rich foods like citrus fruits and bell peppers.
Upper Intake Limit: The maximum daily intake for 14-18 year-olds is 45 mg to avoid toxicity.
Athletic & Vegetarian Needs: Athletes and those on vegetarian diets may require more careful planning or supplementation for adequate iron intake.

Why Iron is Crucial for 18-Year-Olds

Iron is a vital mineral that supports rapid growth and development during adolescence. It plays a key role in producing hemoglobin, a protein in red blood cells that carries oxygen throughout the body. Adequate iron intake is essential for maintaining energy levels, supporting brain function, and building muscle mass, especially during teenage growth spurts. An 18-year-old's body is still undergoing significant changes, and iron is a cornerstone of this process.

For females, the start of menstruation increases their daily iron needs to compensate for the blood and iron lost monthly. This makes adolescent girls particularly vulnerable to iron deficiency anemia if they don't consume enough iron-rich foods.

Recommended Daily Allowances for 18-Year-Olds

The recommended daily allowance (RDA) for iron for an 18-year-old is gender-specific.

18-Year-Old Male: Needs 11 mg of iron per day.
18-Year-Old Female: Needs 15 mg of iron per day.

This gender-based difference is a critical consideration for both teenagers and their parents when planning diets. It's important to remember that these are general guidelines, and individual needs can vary. Highly active athletes, for instance, may require more iron due to losses through sweat and increased demands from intense exercise. Vegetarians or vegans also need special consideration, as the non-heme iron from plant-based sources is less readily absorbed than heme iron from animal products.

Top Dietary Sources of Iron

Getting enough iron typically comes from a balanced diet. Iron can be found in two forms: heme and non-heme iron. Heme iron is found in animal-based foods and is more easily absorbed by the body. Non-heme iron is found in plant-based foods, and its absorption can be enhanced by pairing it with vitamin C.

Heme Iron Sources

Lean red meat (beef)
Poultry (chicken, turkey)
Fish (tuna, sardines)
Shellfish (clams, oysters)

Non-Heme Iron Sources

Beans and lentils
Spinach and other leafy greens
Fortified breakfast cereals and breads
Nuts and seeds
Dried fruit (raisins)

Strategies to Enhance Iron Absorption

To maximize the iron your body absorbs from food, especially non-heme iron, consider these strategies:

Pair with Vitamin C: Consume iron-rich foods with sources of vitamin C, such as citrus fruits, bell peppers, broccoli, and tomatoes. For example, add strawberries to iron-fortified cereal or squeeze lemon juice over a spinach salad.
Separate from Calcium: Avoid consuming high-iron foods at the same time as calcium-rich foods or supplements, as calcium can inhibit iron absorption. This means drinking milk at a different time than a meal high in iron.
Limit Inhibitors: Certain substances in coffee, tea, and some whole grains can inhibit iron absorption. While not necessary to eliminate completely, it's wise to consume them between meals rather than with them.

Comparison of Iron Absorption by Food Type


Food Type	Bioavailability (Absorption)	Examples
Heme Iron (Animal-Based)	High (15-35%)	Lean Red Meat, Poultry, Seafood
Non-Heme Iron (Plant-Based)	Low (2-20%)	Beans, Spinach, Fortified Cereals
With Vitamin C Enhancer	Significantly improved (Non-Heme)	Spinach salad with bell peppers
With Calcium Inhibitor	Reduced (Both Heme and Non-Heme)	Milk consumed with a steak dinner

Iron Deficiency and Toxicity

While it's important to meet your daily iron requirements, both too little and too much iron can cause health issues. Iron deficiency can lead to anemia, causing fatigue, weakness, and poor concentration. Conversely, excessive iron intake can be toxic. The tolerable upper intake level (UL) for individuals aged 14 to 18 is 45 mg per day. Exceeding this limit regularly can lead to side effects like gastrointestinal distress and, in severe cases, more serious health problems. Always consult a healthcare professional before starting any iron supplement regimen. Individuals with specific health conditions may require different iron levels based on professional medical advice.

Conclusion

The amount of iron an 18-year-old needs varies significantly by gender, with females requiring 15 mg per day and males needing 11 mg to support their respective physiological demands. A balanced diet rich in both heme and non-heme iron sources is the best way to meet these needs, but careful consideration should be given to dietary factors that influence absorption. By understanding these differences and focusing on proper nutrition, 18-year-olds can ensure they get the right amount of this essential mineral to support their health and well-being. For specific concerns or to discuss supplementation, a healthcare provider or dietitian should be consulted.

Get more nutritional guidance

For more detailed information on a healthy diet for adolescents and how to meet specific nutrient requirements, visit the Academy of Nutrition and Dietetics website. EatRight.org

Frequently Asked Questions

18-year-old females need more iron (15 mg per day) than males (11 mg per day) primarily because they require extra iron to replace what is lost through menstruation each month.

Yes, it is possible for an 18-year-old to get enough iron from a plant-based diet, but it requires careful planning. Since non-heme iron from plants is less bioavailable, it is important to include good sources like lentils, beans, and fortified cereals and pair them with vitamin C to enhance absorption.

Signs of iron deficiency can include fatigue, weakness, pale skin, cold hands and feet, poor appetite, and shortness of breath. In severe cases, it can lead to iron deficiency anemia.

Yes, excessive iron intake can be toxic. The tolerable upper intake level (UL) for 14 to 18-year-olds is 45 mg per day. High doses can cause gastrointestinal issues and should be discussed with a doctor.

18-year-old athletes can ensure they get enough iron by consuming a balanced diet rich in iron, potentially including both heme and non-heme sources. Since athletes may lose iron through sweat, they should monitor their intake and, if needed, consult a healthcare provider about supplementation.

Yes, because the non-heme iron found in plant-based foods is not as easily absorbed as heme iron from animal products, vegetarians and vegans may need to consume higher overall amounts of iron-rich foods and focus on enhancing absorption with vitamin C.

When eating iron-rich foods, an 18-year-old should avoid consuming large amounts of calcium-rich foods like milk and cheese at the same time, as calcium can inhibit iron absorption. It is also recommended to drink coffee and tea between meals rather than with them.