Heavy Menstrual Bleeding, Diet Raise Iron Deficiency Risk for Teen Girls

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More than half of teen girls surveyed had heavy menstrual cycles, and 40% were iron-deficient — especially those limiting meat intake.

Research published in PLOS One highlights just how common iron deficiency is among teenage girls — and why it’s important to pay attention to both menstrual health and diet. Iron is an essential mineral that helps carry oxygen throughout the body, but adolescents have higher iron needs because of rapid growth and, after menstruation begins, monthly blood loss. When iron levels drop too low, teens may experience fatigue, dizziness, trouble concentrating, headaches, shortness of breath or poor school performance.

The Study

Investigators surveyed 394 girls ages 15 and older from two Swedish high schools to look at how often heavy menstrual bleeding occurs and how it relates to diet and iron levels. Heavy menstrual bleeding (sometimes called HMB) was measured using the SAMANTA questionnaire, a tool designed to help identify menstrual cycles that may be heavier than normal. Students also had blood tests to check their ferritin levels, a marker of iron stores. Teens using birth control were excluded from the analysis.

“There is a knowledge gap regarding the impact of heavy menstrual bleeding and dietary iron intake on iron deficiency in adolescents,” wrote the team of investigators led by Lisa Söderman, a postdoctoral fellow from the Department of Clinical Science and Education at the Karolinska Institutet in Sweden. “Additionally, there is a lack of accurate and accessible tools for screening for heavy menstrual bleeding in this age group, as the SAMANTA questionnaire has not previously been validated for use in adolescents.”

The median age of participants was 16 years, and 27.9% were following a meat-restricted diet.

What They Found

The findings were striking:

• 53% of students had heavy menstrual bleeding.
• 40% had iron deficiency, defined as ferritin below 15 micrograms per liter.
• Certain dietary habits also played a major role. Teens who followed a meat-restricted diet — such as vegetarian or vegan eating patterns — were more likely to have low iron.

When the investigators analyzed the data, they found that heavy menstrual bleeding alone tripled the odds of iron deficiency. A meat-restricted diet also tripled the odds. But when a teen had both heavy menstrual cycles and a meat-restricted diet, the risk skyrocketed: These girls were 13.5 times more likely to have iron deficiency than teens who ate meat and had normal menstrual flow.

This means both “output” (blood loss) and “input” (dietary iron) matter — especially during adolescence.

Investigators said the study’s strength is that it looked at both menstrual patterns and dietary habits together, giving a clearer picture of what affects teen girls’ iron levels. Although there were some limitations — such as the cross-sectional study design, possible recall issues, excluding teens using hormonal contraception, and not collecting data on physical activity or eating disorders — the findings on heavy menstrual bleeding aligned with previous research, suggesting the results are reliable for this age group.

“These findings underscore the importance of identifying and addressing both iron loss and low iron intake when screening for and preventing iron deficiency in adolescents,” concluded investigators.