Why Do Females Require More Iron Than Males?

December 7, 2025 •

3 min read

According to the World Health Organization, iron deficiency is the most common and widespread nutritional disorder in the world, with women of reproductive age being the most susceptible group. Understanding why do females require more iron than males is crucial for proper nutrition and preventing serious health issues like anemia.

Quick Summary

Adult women of reproductive age need nearly double the daily iron intake of men primarily due to monthly blood loss from menstruation. Pregnancy and breastfeeding further increase iron requirements. This physiological difference makes women more prone to iron deficiency anemia without adequate dietary iron.

Key Points

Menstruation causes blood loss: The monthly menstrual cycle is the primary reason for a woman's higher iron need, as blood and its iron content are lost regularly.
Pregnancy increases iron demand significantly: During pregnancy, a woman's blood volume increases dramatically, requiring a much higher iron intake to support both her and the fetus.
Iron needs decrease after menopause: Once menstruation stops, a woman's daily iron requirement typically drops to the same level as an adult male.
Hormones influence iron metabolism: Sex hormones like estrogen and testosterone play roles in regulating iron absorption and storage, contributing to gender differences.
Absorption rates differ for heme and non-heme iron: Iron from animal sources (heme) is absorbed more efficiently than iron from plant sources (non-heme), making dietary choices a key factor.
Iron deficiency can lead to anemia: Without sufficient iron, the body cannot produce enough hemoglobin, leading to anemia, which can cause fatigue, weakness, and other serious health issues.

The Core Difference: Blood Loss and Increased Demand

Menstruation: The Primary Factor

The most significant reason females require more iron is the monthly blood loss that occurs during menstruation. Each menstrual cycle, a woman's body sheds blood and, along with it, a certain amount of iron. The average adult male requires about 8 mg of iron per day, while menstruating women need around 18 mg daily to compensate for these regular losses. This consistent, monthly depletion necessitates a higher baseline intake to prevent the development of iron deficiency and its more severe form, iron-deficiency anemia.

The Demands of Pregnancy and Lactation

Pregnancy and breastfeeding place an even greater demand on a woman's iron stores. During pregnancy, a woman's blood volume expands to support the developing fetus and the placenta. This requires a significant increase in iron intake—often up to 27 mg per day—to produce more hemoglobin for the increased blood supply and to build the fetus's own iron stores before birth. Anemia during pregnancy can lead to complications such as preterm delivery and low birth weight. After childbirth, the needs don't immediately normalize; breastfeeding women also have elevated iron needs.

The Impact of Sex Hormones

Emerging research indicates that sex hormones also play a role in regulating iron metabolism. Estrogen may influence genes related to iron absorption, while testosterone's erythropoietic (red blood cell production) effects contribute to higher hemoglobin concentrations and iron stores in males. These hormonal differences contribute to the disparity in iron status and the higher prevalence of deficiency in females. After menopause, when a woman's menstrual cycles cease, her iron requirement typically decreases to match that of a man's, highlighting the reproductive cycle's central role.

Comparing Iron Needs by Gender and Age


Life Stage	Male (RDA)	Female (RDA)	Primary Reason for Female Need
Ages 14-18	11 mg/day	15 mg/day	Growth spurt and onset of menstruation
Ages 19-50	8 mg/day	18 mg/day	Monthly blood loss from menstruation
Ages 51+	8 mg/day	8 mg/day	Post-menopause; needs stabilize
Pregnancy	N/A	27 mg/day	Increased blood volume for fetus and placenta

Dietary and Absorption Considerations

It is important to remember that iron absorption is a complex process. The iron in food comes in two forms: heme iron (from animal sources) and non-heme iron (from plant sources). Heme iron is more easily absorbed by the body. While women may have higher inherent absorption efficiency to some extent, it's not enough to offset the significant losses during menstruation and pregnancy, especially if their diet is insufficient.

To optimize iron absorption, women should:

Pair non-heme iron sources (e.g., spinach, lentils) with foods rich in Vitamin C (e.g., bell peppers, oranges).
Limit consumption of iron absorption inhibitors like tannins found in tea and coffee during iron-rich meals.
Include lean red meat, poultry, or fish in their diet, as heme iron enhances the absorption of non-heme iron.

Conclusion

In summary, the higher iron requirement for females compared to males is a direct result of biological imperatives, primarily the consistent blood loss associated with menstruation and the increased demands of pregnancy. These physiological factors necessitate a significantly higher iron intake throughout a woman's reproductive years. By understanding these differences and focusing on iron-rich foods and absorption-boosting strategies, women can better protect themselves from iron deficiency and maintain overall health. Consistent awareness and dietary planning are key to ensuring adequate iron levels throughout a woman's life cycle. For personalized advice and diagnosis, always consult a healthcare provider.

Potential Complications of Untreated Deficiency

Left untreated, severe iron deficiency can lead to a number of health issues. Anemia forces the heart to work harder to pump oxygenated blood throughout the body, which can lead to heart problems, including an enlarged heart or heart failure. For pregnant women, it can increase the risk of poor outcomes for both mother and baby. In general, it also weakens the immune system, making individuals more susceptible to infections. You can find more information on iron-deficiency anemia symptoms and treatment on the Office on Women's Health website.

Frequently Asked Questions

Adult women aged 19-50 need about 18 mg of iron per day, while adult men need about 8 mg per day.

Menstruation causes regular blood loss, which depletes a woman's iron stores and necessitates a higher daily iron intake to replenish what is lost each month.

During pregnancy, a woman's blood volume increases significantly to support the developing baby and placenta, which requires a much greater amount of iron to produce additional hemoglobin.

No, after menopause, a woman's menstrual cycles stop, and her daily iron requirements decrease to match those of an adult male, typically around 8 mg per day.

Yes, they may be at higher risk because non-heme iron from plant sources is less readily absorbed than heme iron from animal sources. These individuals may need to consume almost twice as much dietary iron.

Common symptoms include fatigue, weakness, pale skin, brittle nails, hair loss, and difficulty concentrating.

Consuming Vitamin C-rich foods like oranges and bell peppers with iron sources can help increase absorption. Heme iron from meat also improves the absorption of non-heme iron.