Iron

What is Iron?

A mineral your body needs to make hemoglobin and carry oxygen in the blood.

What is iron? Iron is a mineral that our bodies need for growth and development. Your body uses iron to make hemoglobin, a protein in red blood cells. Hemoglobin carries oxygen from the lungs to all parts of the body. Iron is also important for healthy muscles, bone marrow, and organ function. Your body also needs iron to make some hormones. How do you get iron? Iron is found naturally in many foods and is added to some fortified food products. Foods that are high in iron include: Lean meat, seafood, and poultry Iron-fortified breakfast cereals and breads White beans, lentils, spinach, kidney beans, and peas Nuts and some dried fruits, such as raisins Iron is available in supplements, either on its own or as part of many multivitamin/mineral supplements.

What to know about Iron

Understanding Iron means knowing what it reflects, what tends to move it, and the signs that suggest it’s worth a closer look — so you can bring the right questions to your next appointment.

How to read a value in context

Healthy iron levels mean your body has enough iron to make hemoglobin and carry oxygen efficiently, without stores being too low (deficiency) or too high (overload).

Lifestyle factors that influence this marker

• Eating iron-rich foods like lean meat, seafood, and poultry
• Pairing plant-based iron sources with vitamin C to improve absorption
• Including iron-fortified cereals, beans, lentils, and leafy greens
• Avoiding excess tea or coffee with iron-rich meals, which can block absorption
• Always talk to your doctor before starting an iron supplement, since too much iron can be harmful

Tests often checked alongside this

• Ferritin
• Hemoglobin and hematocrit
• Total iron-binding capacity (TIBC)
• Transferrin saturation

How this can show up in how you look and feel

• Pale skin, especially in the face and inner eyelids, is sometimes associated with low iron
• Brittle nails or nails that curve unusually (spooning) can occur with longstanding low iron
• Hair thinning or increased shedding is sometimes linked to low iron
• Cracked corners of the mouth can be associated with iron deficiency
• Many people with low iron have no visible signs until levels drop quite low

What can affect this marker

• Diet and iron-rich foods
• Blood loss, including periods
• Pregnancy and growth spurts
• Gut absorption and gut health

What to track over time

• Your levels across repeat tests
• Energy and fatigue patterns
• Response to diet or supplements
• Alongside ferritin and blood counts

What to ask your doctor

• Is my iron actually low or borderline?
• Should I supplement or eat more iron?
• What's causing ongoing iron loss?
• When should I retest?

This glossary entry is for informational purposes only and is not a substitute for professional medical advice. Read our Medical Disclaimer.