Researchers studied 394 teenage girls in Sweden to understand why so many develop iron deficiency—a condition where your body doesn’t have enough iron to work properly. They found that over half the girls had heavy periods, and 40% had low iron levels. The study discovered that heavy menstrual bleeding and avoiding meat both increase iron deficiency risk. When girls had both heavy periods AND didn’t eat meat, their risk of iron deficiency jumped dramatically. This research shows that teenage girls need to pay attention to both how much they’re bleeding and what they’re eating to stay healthy.

The Quick Take

  • What they studied: Whether heavy menstrual bleeding and eating habits (especially avoiding meat) affect how many teenage girls develop iron deficiency
  • Who participated: 394 teenage girls aged 15 and older from two high schools in Sweden who had started their periods
  • Key finding: Girls with heavy periods had 3 times higher risk of iron deficiency, girls avoiding meat had 3.5 times higher risk, and girls with BOTH conditions had 13.5 times higher risk compared to girls with normal periods who eat meat
  • What it means for you: If you’re a teenage girl with heavy periods or you don’t eat meat, you should talk to a doctor about checking your iron levels. This is especially important if you have both conditions. Simple changes to your diet or medical treatment for heavy periods could help prevent serious iron deficiency.

The Research Details

This was a cross-sectional study, which means researchers collected information from all participants at one point in time rather than following them over months or years. The study took place in 2023 at two high schools in Sweden. Teenage girls filled out a detailed survey called the SAMANTA questionnaire that asked about their menstrual bleeding patterns—specifically whether their periods were heavier than normal. Researchers also took blood samples from each girl to measure their iron levels. The girls reported what they ate, including whether they avoided meat. Researchers then looked at the data to see which factors were connected to low iron levels.

This approach is useful because it gives researchers a clear snapshot of the problem in a real teenage population. By collecting blood samples alongside survey answers, the researchers could confirm actual iron deficiency rather than just relying on what girls reported. Understanding both the bleeding patterns and eating habits together helps doctors know which girls need the most help.

This study has several strengths: it included a reasonably large group of 394 girls, used a validated questionnaire for measuring heavy periods, and confirmed iron deficiency with actual blood tests. However, because it’s a snapshot in time, we can’t be completely sure that heavy periods and diet directly cause iron deficiency—only that they’re connected. The study was done in Sweden, so results might be slightly different in other countries with different populations.

What the Results Show

The researchers found that iron deficiency was very common in this group of teenage girls—affecting 40% of them. More than half (53%) reported having heavy menstrual bleeding. When researchers looked at what caused iron deficiency, they found two main culprits: heavy periods and avoiding meat. Girls with heavy periods were 3 times more likely to have low iron than girls with normal periods. Girls who didn’t eat meat were 3.5 times more likely to have low iron than girls who did eat meat. But here’s the really important finding: when a girl had BOTH heavy periods AND avoided meat, her risk jumped to 13.5 times higher than a girl with normal periods who eats meat. This huge jump shows that these two problems work together to create a serious iron deficiency risk.

The study confirmed that the teenage years are a critical time for iron deficiency because girls’ bodies need more iron during growth spurts, and they lose iron through menstruation. The combination of increased need and increased loss makes teenage girls especially vulnerable. The research also showed that dietary choices matter significantly—the type of food girls eat can either protect them from or increase their risk of iron deficiency.

Previous research has shown that teenage girls are at higher risk for iron deficiency than other age groups, but this study provides new evidence about how much heavy periods and diet choices matter together. The finding that combining these two risk factors creates such a dramatic increase in deficiency risk is particularly important and suggests that doctors need to look at both factors when treating teenage girls.

Because this study only looked at girls in Swedish high schools, the results might not apply exactly the same way to girls in other countries or different environments. The study collected information at just one point in time, so we can’t know if the heavy periods or low iron came first or how they might change over time. The study relied on girls reporting their own eating habits and period symptoms, which might not always be completely accurate. Additionally, the study didn’t look at other factors that might affect iron levels, like how much exercise the girls did or whether they had other health conditions.

The Bottom Line

If you’re a teenage girl, especially one with heavy periods or who avoids meat, ask your doctor to check your iron levels with a blood test. If you have heavy periods, talk to a doctor about treatment options—these can range from over-the-counter pain relievers to prescription medications or other medical treatments. If you avoid meat, make sure you’re eating other iron-rich foods like beans, lentils, fortified cereals, dark leafy greens, and eggs. Taking an iron supplement might also help, but only under a doctor’s guidance. These recommendations are supported by strong evidence from this study.

This research is especially important for teenage girls, their parents, and their doctors. Girls with heavy periods should definitely pay attention. Girls who are vegetarian or vegan should be particularly careful about their iron intake. Boys and adult women should also be aware of these findings if they have teenage girls in their lives. However, this study specifically looked at teenage girls, so the exact findings might not apply the same way to younger girls or adult women.

If you start making dietary changes or get treatment for heavy periods, it typically takes 2-3 months to see improvements in iron levels. Some symptoms like tiredness might improve faster, while others take longer. It’s important to have your iron levels checked again after a few months to see if changes are working.

Want to Apply This Research?

  • Track your period flow (light, normal, or heavy) and iron-rich foods eaten daily. Rate your energy level each day on a scale of 1-10 to monitor potential iron deficiency symptoms like fatigue.
  • Set a daily reminder to eat one iron-rich food (meat, beans, lentils, fortified cereal, or leafy greens). If you have heavy periods, use the app to log when you start treatment and track any changes in flow over the next 2-3 months.
  • Create a monthly summary showing period heaviness trends and average daily iron intake. Set a reminder to discuss blood test results with your doctor every 3 months if you’re at risk for iron deficiency.

This research provides important information about iron deficiency in teenage girls, but it should not replace professional medical advice. If you’re a teenage girl concerned about heavy periods, iron deficiency, or related symptoms, please consult with a doctor or healthcare provider for proper evaluation and treatment. Blood tests are necessary to diagnose iron deficiency. Anyone considering dietary changes or supplements should discuss them with a healthcare professional first, especially if they have existing health conditions or take medications. This study was conducted in Sweden and may not apply identically to all populations.