What Does Ferrous and Folic Acid Do to the Body?

January 12, 2026 •

4 min read

According to the World Health Organization, more than 40% of pregnant women worldwide are anemic, often due to deficiencies in iron and folic acid. Together, these vital nutrients support the body's ability to produce healthy red blood cells, carry oxygen, and prevent serious health conditions, particularly during periods of increased nutritional demand.

Quick Summary

Ferrous iron and folic acid are crucial for red blood cell formation and preventing anemia. Iron facilitates oxygen transport via hemoglobin, while folic acid is essential for DNA synthesis and cell division. They are often combined in supplements for synergistic effects, vital during pregnancy and for treating deficiencies.

Key Points

Red Blood Cell Production: Ferrous iron is essential for creating hemoglobin, while folic acid is crucial for forming healthy red blood cells.
Anemia Prevention: The combination effectively prevents and treats iron-deficiency anemia and megaloblastic anemia by ensuring both red blood cell formation and oxygen transport.
Fetal Development: Folic acid is vital during early pregnancy to prevent neural tube defects, while iron supports the growth of the fetus and placenta.
Cellular Health: Folic acid supports DNA synthesis and cell division throughout the body, making it essential for growth and repair.
Energy and Immunity: Iron's role in oxygen transport boosts energy levels and supports immune function throughout the body.
Dietary Considerations: Absorption can be affected by other foods and supplements; consult a healthcare provider for proper guidance, especially concerning interactions with other medications.

The Core Functions of Ferrous Iron

Ferrous iron is a form of iron that is readily absorbed by the body. Iron is an essential mineral with several critical physiological functions. Its most famous role is in the production of hemoglobin, a protein found in red blood cells that is responsible for carrying oxygen from the lungs to the rest of the body's tissues.

Without sufficient iron, the body cannot produce enough hemoglobin, leading to iron-deficiency anemia. This condition results in a reduced oxygen supply to the body, causing symptoms like fatigue, weakness, and shortness of breath. Beyond oxygen transport, iron also plays a significant role in:

Supporting the immune system
Promoting healthy sleep patterns
Facilitating energy production at a cellular level
Maintaining cognitive function

The Role of Folic Acid in the Body

Folic acid, the synthetic version of the B-vitamin folate, is vital for cellular health and development. It plays a crucial part in the synthesis and repair of DNA, a process required for the production of healthy new cells.

One of its most important functions is in the maturation of red blood cells. A deficiency in folic acid can cause megaloblastic anemia, where red blood cells are abnormally large and immature, leading to a reduced oxygen-carrying capacity.

Key functions of folic acid include:

Cell Division: Essential for creating new cells during periods of rapid growth, such as during pregnancy and infancy.
Neural Tube Development: Crucial for the proper formation of a baby's brain and spinal cord during early pregnancy, preventing neural tube defects like spina bifida.
Homocysteine Regulation: Helps regulate homocysteine, an amino acid that can increase the risk of cardiovascular disease when present at high levels.

The Synergy of Ferrous and Folic Acid

Ferrous iron and folic acid are often prescribed together because they work synergistically, particularly in preventing and treating anemia. While folic acid aids in the production of new red blood cells, ferrous iron provides the raw material (iron) needed to fill those cells with hemoglobin for effective oxygen transport.

Combining these two nutrients offers a comprehensive approach to correcting deficiencies and addressing the root causes of many types of anemia. This combination is especially important for women of childbearing age, pregnant women, and individuals with dietary restrictions that make them susceptible to deficiencies.

How Deficiencies Manifest

Deficiencies in either nutrient can lead to anemia, though the specific type and symptoms can differ. Recognizing these signs is important for timely intervention.

Iron Deficiency Symptoms:

Extreme fatigue and weakness
Pale skin
Shortness of breath
Headaches
Brittle nails
Unusual cravings (pica)

Folic Acid Deficiency Symptoms:

Persistent fatigue and weakness
Sore or swollen tongue
Mouth ulcers
Gastrointestinal issues like diarrhea
Cognitive issues like memory problems and confusion

Comparison Table: Ferrous Iron vs. Folic Acid


Feature	Ferrous Iron	Folic Acid (Vitamin B9)
Classification	Mineral	B-vitamin (synthetic)
Primary Role	Oxygen transport via hemoglobin production	DNA synthesis and cell division
Primary Deficiency	Iron-deficiency anemia (small, pale red cells)	Megaloblastic anemia (large, immature red cells)
Synergistic Action	Provides hemoglobin for oxygen transport	Supports the creation of healthy red blood cells
Pregnancy Importance	Supports placenta and fetal development; prevents maternal anemia	Crucial for preventing neural tube defects
Dietary Sources	Red meat, seafood, legumes, leafy greens	Leafy greens, citrus fruits, fortified cereals

Potential Side Effects and Considerations

While essential, supplementation should be managed carefully. Common side effects associated with ferrous iron include constipation, nausea, stomach pain, and dark-colored stools. High doses can be toxic, particularly for children, so supplements should be kept out of reach. Folic acid typically has mild side effects, but excessive intake, especially in the presence of an undiagnosed vitamin B12 deficiency, can mask symptoms of the B12 deficiency and lead to nerve damage. Always consult a healthcare provider before beginning supplementation to ensure it is appropriate for your health needs.

For more information on nutrition and health guidelines, the World Health Organization is a valuable resource.

Conclusion

Ferrous iron and folic acid are two distinct yet deeply interconnected nutrients that are indispensable for human health. Their primary collaborative function is to ensure the body produces and maintains an adequate supply of healthy, oxygen-carrying red blood cells. While ferrous iron is the mineral cornerstone of hemoglobin, folic acid serves as the cellular-level architect, building the very foundation of red blood cells and DNA. Their combined action is particularly critical for vulnerable populations, including pregnant women, helping to prevent serious health issues like anemia and birth defects. Understanding the unique role of each, and their powerful synergy, empowers individuals to make informed dietary and supplemental choices to support overall well-being.

Frequently Asked Questions

Women of childbearing age, pregnant women, and individuals diagnosed with iron-deficiency anemia or megaloblastic anemia are most likely to benefit from a combined ferrous and folic acid supplement.

Yes, you can take ferrous and folic acid separately, as they are distinct nutrients. However, they are often combined into a single supplement to address both iron and folate deficiencies simultaneously, especially in cases of anemia.

Ferrous iron is found in red meat, seafood, beans, and fortified cereals. Folic acid (folate) is abundant in leafy green vegetables, citrus fruits, and legumes, and is used to fortify many grain products.

During pregnancy, folic acid is crucial for preventing neural tube defects in the developing baby, while iron supports the increased blood volume and oxygen supply needed by both mother and fetus.

A combined deficiency can cause severe fatigue, weakness, shortness of breath, pale skin, headaches, and in some cases, a sore tongue and gastrointestinal issues.

Common side effects include constipation, nausea, and stomach upset, especially from the iron component. It is important to follow dosage instructions to minimize these effects.

Yes, these supplements can interact with certain antibiotics, antacids, and medications for thyroid conditions. It is important to tell your doctor about all current medications before starting supplementation.