Iron Deficiency and Anemia: What You Need to Know

You are exhausted in a way that sleep does not fix. You get winded doing things that should not be hard. Your mind feels foggy, your body heavy. You might chalk it up to stress, aging, or just life - but iron deficiency could be the underlying cause.

Iron deficiency is the most common nutritional deficiency in the world, affecting roughly 25% of the global population. Yet it is frequently overlooked, undertested, or dismissed with reassurances that levels are "normal" when they may be suboptimal.

What Iron Does in Your Body

Iron is essential - your body cannot function properly without it.

Oxygen transport is iron's most critical role. Iron is a central component of hemoglobin, the protein in red blood cells that carries oxygen from your lungs to every cell in your body. Without adequate iron, you simply cannot deliver enough oxygen to your tissues.

Energy production depends on iron. Beyond oxygen transport, iron is directly involved in cellular energy production. Low iron means low energy at the cellular level.

Brain function requires iron. Iron is involved in neurotransmitter synthesis and myelin production (the coating on nerve cells). Deficiency affects concentration, memory, and cognitive function.

Immune function relies on iron for proper immune cell function and pathogen defense.

Thyroid function depends on adequate iron for the production of thyroid hormones.

Iron Deficiency Versus Anemia

These terms are related but not identical:

Iron deficiency occurs when your body's iron stores are depleted. You may have symptoms even before full-blown anemia develops. This is called "iron deficiency without anemia" or "latent iron deficiency" - and it is often missed.

Iron deficiency anemia occurs when iron depletion has progressed to the point where your body cannot produce enough healthy red blood cells. Hemoglobin levels drop, and oxygen-carrying capacity is reduced.

Many people suffer from iron deficiency for months or years before it progresses to measurable anemia. If your ferritin (iron storage) is low but your hemoglobin is still in range, you may be told you are fine - even though you feel terrible.

Why Iron Deficiency Happens

Not getting enough iron. Dietary iron comes in two forms: heme iron (from animal sources, more easily absorbed) and non-heme iron (from plant sources, less easily absorbed). Vegetarians and vegans are at higher risk, though deficiency can occur regardless of diet.

Not absorbing iron well. Even if you eat enough iron, gut conditions (celiac disease, inflammatory bowel disease, low stomach acid, H. pylori infection) can impair absorption. Certain medications (proton pump inhibitors, antacids) also reduce absorption.

Losing too much iron. Blood loss is a major cause of iron deficiency. For premenopausal women, heavy periods are the most common cause. Other sources of blood loss include gastrointestinal bleeding (ulcers, polyps, hemorrhoids), frequent blood donation, and internal bleeding that may not be obvious.

Increased requirements. Pregnancy dramatically increases iron needs. Growing children and adolescents need more iron. Athletes, particularly endurance athletes, have higher requirements.

Recognizing the Signs

Iron deficiency can be subtle at first, with symptoms developing gradually as stores deplete:

Fatigue and weakness - the hallmark symptom. You feel exhausted despite adequate sleep. Physical activities that were once easy become draining.

Shortness of breath - getting winded from mild exertion like climbing stairs.

Pale skin and mucous membranes - check your inner lower eyelid, gums, and nail beds for pallor.

Rapid or irregular heartbeat - your heart works harder to compensate for reduced oxygen-carrying capacity.

Cold hands and feet - poor oxygenation affects circulation to extremities.

Headaches and dizziness - particularly with exertion.

Brittle nails - that may become spoon-shaped in severe deficiency.

Restless legs - the urge to move legs, especially at night.

Pica - unusual cravings for non-food items like ice, dirt, or starch.

Brain fog and difficulty concentrating - cognitive symptoms are common but often attributed to other causes.

Hair loss - iron deficiency is a common contributor to hair shedding.

Getting Properly Tested

Basic blood work often misses iron deficiency. A complete iron panel includes:

Ferritin - your iron storage marker. This is the most important test for iron status. Conventional "normal" ranges start very low (often 12 or 15), but optimal levels are generally considered to be at least 50-70 (some experts suggest even higher for optimal function).

Serum iron - iron circulating in blood (fluctuates and is less useful alone).

Total Iron Binding Capacity (TIBC) - measures transferrin, which carries iron. High TIBC suggests iron deficiency.

Transferrin saturation - percentage of transferrin bound to iron. Low levels indicate deficiency.

Hemoglobin - only drops after significant depletion, so a "normal" hemoglobin does not rule out iron deficiency.

If you suspect iron deficiency, ask for a complete iron panel, not just a CBC (complete blood count).

Addressing Iron Deficiency

Dietary Strategies

Heme iron sources (better absorbed): red meat, poultry, fish, liver

Non-heme iron sources (pair with vitamin C to improve absorption): leafy greens, legumes, fortified foods, dried fruits

Enhance absorption by consuming vitamin C with iron-rich foods and avoiding coffee or tea with meals (tannins inhibit absorption).

Avoid calcium with iron - calcium competes with iron for absorption.

Supplementation

When deficiency is significant, food alone often cannot restore levels quickly enough. Supplementation may be needed.

Iron supplements come in many forms:

• Ferrous forms (sulfate, gluconate, fumarate) - common and inexpensive but can cause constipation and stomach upset
• Iron bisglycinate - gentler on the stomach and well-absorbed
• Heme iron polypeptide - derived from animal sources, very well absorbed
• Slow-release formulations - may reduce side effects but absorption can be less reliable

Take iron on an empty stomach if tolerable (absorption is better) or with a small amount of food containing vitamin C if stomach upset occurs.

Important: Iron supplementation should be guided by testing. Taking iron when you do not need it can cause problems - iron overload is harmful. Test, supplement appropriately, and retest to confirm improvement.

Address Underlying Causes

If you are losing iron through heavy periods, GI bleeding, or other means, supplementation is just a bandage unless you address the source. Work with a healthcare provider to identify why you are deficient, not just to treat the deficiency itself.

Do Not Accept "Normal"

If you have symptoms of iron deficiency but have been told your levels are normal, look at the actual numbers. A ferritin of 15 is technically in the normal range but is far from optimal - and you may feel it. Advocate for interpretation of your results in the context of your symptoms, not just against a reference range.

Iron deficiency is common, treatable, and makes an enormous difference in how you feel when addressed. You deserve to have adequate energy for your life.

Want to understand fatigue more broadly? Explore the causes and types of fatigue or learn about natural supplements for energy.