There are few health problems that affect billions of people at any given time. There are even fewer that could be reduced substantially through pretty cheap interventions.

Anemia is one of them. Estimates suggest that one in four people globally has anemia; that’s two billion people in total.¹ Almost one in three women and almost 40% of all children suffer from it.

While anemia is much more common in poorer countries, it’s also a significant problem in rich ones. I have family members and friends who have struggled with it for a long time. And I probably know many more who have it but are undiagnosed.

One of the reasons why anemia is so overlooked is that its symptoms are often subtle: in most cases, it’s fatigue and weakness. These symptoms can be common for various reasons, making them harder to attribute to a specific condition. Even in children, when anemia can lead to delays in cognitive and physical development and poor concentration, the signs are not obvious or can’t be linked directly to micronutrient deficiencies.

Severe anemia can lead to much more drastic outcomes, though. Anemia during pregnancy can significantly increase the risks of low birthweight babies and, therefore, the risk of infant mortality.² It also increases the risk of maternal mortality, especially if there is a lot of blood loss during childbirth.³ And anemia in pregnant women is extremely common, especially in lower-income countries. You can see this in the map: in some of the poorest countries, more than half of pregnant women are anemic.

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While anemia and iron deficiency (which is its leading cause) don’t directly kill a large number of people, it makes up a large share of the world’s disease burden. The Global Burden of Disease study estimates that it accounts for about 2% of the world’s disability-adjusted life years. This might not sound like a lot, but it’s more than other widely recognized health problems like HIV, breast cancer, and Alzheimer’s disease.

Iron deficiency is the most common cause of anemia

Around half to two-thirds of anemia cases globally are caused by nutritional deficiencies.¹ Deficiencies in vitamin A, B₁₂, and folic acid can lead to anemia, but the most common one, by far, is iron deficiency.

Unsurprisingly, people are at much higher risk of anemia when they have low dietary diversity.⁴ This tends to correlate very strongly with income — richer people can afford more varied diets — which is one reason why anemia is much more common in lower-income countries, as this chart shows.

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But there are other causes of anemia too: infectious diseases such as malaria, HIV, and schistosomiasis; chronic diseases such as kidney disease; genetic disorders such as sickle cell disease; and finally, blood loss in women — such as heavy menstrual cycles or even hemorrhage during pregnancy.

Infectious diseases, in particular, are more common in lower-income countries, which is another reason why rates of anemia are higher there.

Women and children are at a much higher risk of iron deficiency and anemia than men. This is because they often need more iron relative to the amount of calories they consume.

Nutrient-dense foods rich in minerals like iron are essential during childhood to maintain healthy growth. This is true for boys and girls.

After puberty, iron deficiency is much more common in women. This is because they lose iron stores during menstruation, and iron requirements increase around threefold during pregnancy.⁵ Among people aged 15 to 49, the Global Burden of Disease study estimates that cases of anemia and cases of iron deficiency are three times as common in women than men.⁶

Only at older ages do the risks for men and women both rise to similar levels.

The maps below show the estimated share of children and women of reproductive age who have anemia. It’s much more common in Sub-Saharan Africa and South Asia, where the majority are anemic. But even in richer countries, less than a handful have rates below 10%.

Click to open interactive version

Click to open interactive version

Progress on anemia has been slow, but some countries have shown it’s possible

We know that high rates of anemia are not inevitable: around 10% to 15% of women in rich countries are anemic, compared to more than 50% in poorer countries.

However, progress in reducing rates of anemia has been incredibly slow in recent decades. Globally, the share of pregnant women and women of reproductive age who are anemic has not changed since 2000.

Reductions among children have been slightly more promising: the share of under-fives that are anemic dropped from 48% to 39% between 2000 and 2019.

While progress has been slow globally, some countries have made much faster strides in the last few decades.

In the chart below, you can see the change in the share of children who are anemic between 2000 and 2019. Each line represents one country. I’ve highlighted a few countries that have reduced rates quite a lot: China, Nepal, Brazil, Bolivia, Uzbekistan, and Iran.

Click to open interactive version

There are also examples of impressive reductions among women. See the chart below: rates have more than halved in the Philippines and fallen by two-thirds in Guatemala.

While the stagnation at the global level is worrying, these positive developments show that it is a tractable problem that we can tackle with the right interventions.

The Exemplars in Global Health project did an in-depth review of what the Philippines has done to tackle anemia, and it has several insights that other countries can draw on. Increasing access to family planning — and making contraceptives available as essential medicines — improving rates of antenatal care and giving women access to iron-folic supplements before and during pregnancy have been key to its success.

I’ll now go into some of these interventions in more detail.

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Reducing nutritional deficiencies that cause anemia could be cheap

Nutritional deficiencies — mostly a lack of iron — cause around half of the global anemia cases.

Improving iron supply is the easiest and quickest way to massively reduce the burden of anemia. It’s probably the cheapest, too.

There are a few ways to make sure people get enough iron.

The first and most obvious is to ensure they have a diverse diet and are getting enough through the food they eat: a balanced diet of cereals, fruit, vegetables, pulses, meat, dairy, or other iron-rich plant proteins.⁴ In an ideal world, this would be the solution. But the reality is that billions of people can’t afford a healthy diet. While we need to ensure they eventually can, this will not change overnight. This is the long-term solution, but it’s not going to solve the problem any time soon.

A more direct way is delivering iron supplements to those who need them most. The World Health Organization strongly recommends giving pregnant women iron supplements combined with folic acid in settings where iron deficiency is widespread. This reduces rates of low-birth-weight children and improves other birth outcomes, especially when combined with other essential nutrient supplements.⁷ Of course, iron supplements can also be given at other stages of life, and there is some evidence of improved cognitive development and concentration in children and adolescent girls, where the risk of anemia is also very high.⁸ Iron supplementation is cheap, costing just $1 to $2 per pregnancy.

When anemia is severe and small doses of supplements are not sufficient, it can be treated through one-off iron injections. This tends to be more effective than supplements in the form of pills or capsules but is more expensive and requires medical infrastructure to set up.⁹ One option is to incorporate injections into prenatal appointments so that pregnant women are offered effective treatment during high-risk periods.

Finally, micronutrient deficiencies can be tackled through food fortification. This is when vitamins and minerals are added to foods during the processing stage. This can be done extremely cheaply — and can reach a large number of people at once — but relies on people accessing their food through a more centralized system of producers. It’s much harder to reach people that buy from local markets or live in rural areas.

How to reduce anemia cases from other causes

As I wrote earlier, there are other causes of anemia beyond nutritional deficiencies.

It’s easier said than done, but preventing and treating infectious diseases such as malaria, HIV, and hookworm disease would have a big impact on reducing anemia cases, especially in lower-income countries.¹⁰ There are many other good reasons to prevent these fatal diseases, but it’s an additional benefit. Treated bednets and antimalarials to tackle malaria, antiretroviral therapy drugs to manage HIV, and deworming programs are all relatively cheap health interventions that we should be prioritizing to save lives in any case.¹¹

Since many cases of anemia are also associated with menstrual issues or pregnancy in women, improving access to prenatal and antenatal care and contraception can help. Anemia is more common in very young mothers — because nutritional demands are already higher during adolescence — so providing higher-quality care for teenage mothers before and after pregnancy can reduce some of these risks.¹²

Contraceptive pills might be an option for non-pregnant women who have heavy menstrual cycles, which makes anemia much more likely.¹³ This is a relatively low-cost intervention but is not readily available to women in many countries.

Other genetic causes of anemia, such as sickle cell disease, tend to be harder and more expensive to manage. Since these disorders are often not curable, the main way of managing anemia is through blood transfusions. This is more expensive than other interventions, but it is the main way of managing anemia when sickle cells are the cause.¹⁴

But there are more than a billion people in the world who suffer from anemia that could be managed relatively cheaply. The effects might not be directly visible, but it would make a massive difference, giving people their energy back and giving children the opportunity to develop physically and mentally to their full potential.

Continue reading on Our World in Data

Half of all child deaths are linked to malnutrition

Improving the nutrition of mothers and children could save many lives at a relatively low cost.

Three billion people cannot afford a healthy diet

A healthy, nutritious diet is much more expensive than a calorie sufficient one. As a result, three billion people cannot afford a healthy diet.

Hannah Ritchie (2024) - “Billions of people suffer from anemia, but there are cheap ways to reduce this” Published online at OurWorldinData.org. Retrieved from: 'https://ourworldindata.org/billions-people-suffer-anemia-cheap-ways-reduce' [Online Resource]

@article{owid-billions-people-suffer-anemia-cheap-ways-reduce,
    author = {Hannah Ritchie},
    title = {Billions of people suffer from anemia, but there are cheap ways to reduce this},
    journal = {Our World in Data},
    year = {2024},
    note = {https://ourworldindata.org/billions-people-suffer-anemia-cheap-ways-reduce}
}

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