A new study published in PLOS One sheds light on why iron deficiency remains so common in adolescent girls. The researchers found that teens who have heavy menstrual bleeding and follow meat-restricted diets had dramatically higher odds of iron deficiency compared with those who eat an omnivorous diet and report normal menstrual flow.
The team analyzed ferritin levels, a marker of the body’s iron stores, among teenage girls in Sweden and Canada. They looked at two factors known to influence iron status: menstrual blood loss and dietary patterns. While each factor alone can affect iron levels, the study suggests the combination may pose the greatest risk.
Girls who reported heavy menstrual bleeding had lower ferritin concentrations on average than those with typical cycles. The difference was even more pronounced among teens who avoided meat, a primary source of heme iron, which the body absorbs more easily than iron from plant foods. When those two factors occurred together, the odds of iron deficiency were nearly 14 times higher compared with girls who reported normal menstrual flow and ate an omnivorous diet.
Iron deficiency is common worldwide and can affect energy, immunity and cognitive function. Adolescents are at particular risk because their bodies need more iron to support growth, and many enter their teen years with already low iron intake.
The authors note that menstrual symptoms and diet choices vary widely among teens, and the study cannot establish cause and effect. But the findings highlight the importance of paying attention to both menstrual health and dietary iron, especially for girls who experience heavy bleeding or avoid iron-rich foods.
Iron sources such as beans, lentils, fortified cereals, leafy greens, eggs, poultry and red meat can help support healthy iron levels, as can pairing plant-based iron with vitamin C-rich foods to boost absorption. Teens with fatigue, frequent illness or heavy periods may benefit from talking with a clinician about iron testing.
This research was supported by regional health and clinical research funding agencies in Sweden, as well as open-access support from Karolinska Institutet.