Anemia is a major health problem, with nearly 2 billion people^[1] affected globally. It afflicts more people worldwide than low back pain or diabetes – or even anxiety and depression combined.

Despite this, investments in reducing anemia have failed to substantially reduce the massive burden of anemia globally over the last few decades.

People become anemic^[2] when their blood lacks enough healthy red blood cells to carry oxygen throughout the body. This decreased oxygen delivery causes many of the most common symptoms of anemia^[3], including fatigue, shortness of breath, lightheadedness, difficulty concentrating and challenges with work and daily life tasks.

In addition to its direct health effects, anemia can inhibit brain development and fine motor skills^[4] in children and heighten the risk of stroke^[5], cardiovascular disease^[6], dementia^[7] and other chronic illnesses in older adults. Anemia during pregnancy^[8] can lead to increased rates of anxiety and depression, early labor, postpartum hemorrhage, stillbirth and low birth weight. Infections for both mother and baby are also more likely when the mother is anemic.

We are global^[9] health^[10] researchers^[11] with expertise in epidemiological modeling of anemia alongside other maternal, neonatal and nutritional disorders.

Our work is part of the Global Burden of Disease Study^[12], a large research study comprehensively estimating health loss due to hundreds of diseases, injuries and risk factors around the globe. Through our analysis, we have produced annual estimates of anemia prevalence by underlying cause for 204 countries and territories, by age and sex, from 1990 to the present. We have collected thousands of data points across hundreds of sources to produce the most comprehensive picture of anemia burden.

Anemia is a widespread problem

Anemia is diagnosed by a simple blood test and can be caused by a number of underlying conditions.

Decreases in healthy red blood cells can occur due to excessive loss of existing red blood cells, such as through bleeding or destruction by the body’s immune system. Anemia can also occur due to decreased production of new red blood cells or changes in the normal structure or lifespan of red blood cells that make them less effective.

Globally, anemia is the third-largest cause of disability: Our recent study found that nearly 1 in 4 people has anemia^[13]. This burden is concentrated among children younger than 5 years and adolescent girls and women, one-third of whom are anemic. Anemia rates are particularly high in sub-Saharan Africa and South Asia, where we estimated that 40% – or two out of every five people – have anemia.

Reductions in anemia rates have been slow and uneven, dropping from 28% to 24% globally from 1990 to 2021. Adult males have fared better, with young children and adolescent girls and women – who bear the highest burden of anemia – showing the least progress. On the positive side, there has been a shift toward milder forms of anemia, which result in much less disability compared to severe anemia.

Reducing anemia means tackling underlying causes

Substantially reducing anemia globally is complicated by its many underlying causes. Dietary iron deficiency is the most common cause^[14] across the globe. But other important drivers of anemia include blood disorders such as sickle cell disease^[15] or thalassemias^[16], infectious diseases like malaria^[17] and hookworm^[18], gynecologic and obstetric conditions, inflammation^[19] and chronic diseases.