Iron Loss Explains Why You're Tired All the Time


Women often find themselves low on iron due to the loss of blood during menstruation. The fix may be as simple as a little iron supplement.

The Doctor Will See You Now

If you're a woman and you constantly feel tired, maybe a little iron could help. A new study found that iron supplementation may be helpful even for women who have iron levels that are not low enough to be diagnosed with anemia. However, read on before you run out and buy a bottle of iron supplement.

Researchers conducted a randomized controlled trial of nearly 200 women between the ages of 18 and 50 who were still menstruating and had gone to their physicians complaining of fatigue. Fatigue is a common complaint in primary patient practices, particularly among female patients. Fourteen to 27 percent of patients suffer from fatigue with women three times more likely to report the problem to their physician than men. Needless to say, low iron is far from the only cause of women's fatigue.

Low iron levels may be an under-recognized reason for fatigue in pre-menopausal women because of the monthly loss of blood during the menstrual cycle.

None of the women in the study had iron levels low enough to be diagnosed with anemia, but they reported considerable fatigue without any observable medical explanation. The study participants were randomly assigned to take either a daily oral supplement of 80 milligrams of prolonged-release ferrous sulfate or a placebo for 12 weeks. Neither the physicians nor the study participants knew which group of women was taking the supplement versus the placebo. After 12 weeks, fatigue was decreased by 50 percent in the women taking the iron supplement.

Low iron levels may be an under-recognized reason for fatigue in pre-menopausal women because of the monthly loss of blood during the menstrual cycle. Women of childbearing age need 18 milligrams of iron per day; however, the average woman only consumes 12 to 13 milligrams per day.

A low iron level is not the same thing as iron deficiency anemia. Iron deficiency anemia develops over time. In the early stages of iron deficiency, iron levels in the blood decrease as do levels of ferritin, a protein in the blood that stores iron. The next stage is characterized by a further decrease in iron levels and an increase in transferrin levels. Transferrin is the protein that transports iron in the blood. This increase is an adaptive response in an attempt to enhance iron absorption in the body.

In the third and last stage of iron deficiency, the lack of iron in the blood limits the formation of hemoglobin causing red blood cells to become small and pale in color, and blood tests reveal iron deficiency anemia. The result is fatigue, among other symptoms, because hemoglobin carries oxygen to the cells of the body.

A person who feels fatigued should not self-diagnose and take an iron supplement. A supplement could obscure a serious medical condition such as a bleeding ulcer. Taking too much iron can also be problematic and dangerous as iron levels may build up in the body and cause major organ failure.

Chronic fatigue should be evaluated by a physician and iron supplements taken only after laboratory tests confirm the need for one.

The study was published in the Canadian Medical Association Journal.

This article originally appeared on, an Atlantic partner site.

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Beth Fontenot is a registered dietitian and a licensed dietitian/nutritionist. She serves on the Louisiana Board of Examiners in Dietetics and Nutrition and writes for

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