Researchers looked at how many people worldwide don’t get enough vitamin A, which is important for eyesight and fighting infections. Using data from 1990 to 2021, they found that the problem has gotten better over time, especially in wealthy countries. However, vitamin A deficiency still causes serious health problems for millions of people, particularly young children in poorer regions. Scientists predict the situation will continue improving through 2050, but it will require focused efforts to help the people who need it most.

The Quick Take

  • What they studied: How common vitamin A deficiency is around the world, how it has changed since 1990, and what scientists predict will happen by 2050
  • Who participated: This wasn’t a study with individual people. Instead, researchers analyzed health data from 195 countries collected over 31 years to understand global patterns of vitamin A deficiency
  • Key finding: The global burden of vitamin A deficiency dropped by about 44% from 1990 to 2021. The problem decreased faster in wealthy countries, but remains a major issue in poorer regions, especially affecting children under 5 years old
  • What it means for you: If you live in a developed country, vitamin A deficiency is unlikely to affect you. However, if you live in or travel to low-income regions, or work in global health, this research shows where help is most needed. The trend is positive, but progress requires continued investment in nutrition programs

The Research Details

Scientists used a massive global health database called the Global Burden of Disease Study 2021, which collects health information from countries around the world. They looked at 31 years of data (1990-2021) to see how vitamin A deficiency changed over time. They measured the impact using two main numbers: DALYs (which count years lost to illness or disability) and YLDs (which count years spent living with disability). They broke down the data by age, gender, and how wealthy different regions are. Then they used mathematical models to predict what would happen from 2022 to 2050.

This approach is important because it shows the real-world impact of vitamin A deficiency across the entire world, not just in one country or group. By tracking changes over 31 years, researchers can see if efforts to fix the problem are actually working. The predictions help governments and health organizations plan where to focus their efforts in the future.

This study used data from the Global Burden of Disease Study, which is one of the most respected sources of health information worldwide. The researchers analyzed trends carefully using statistical methods designed to detect real changes. However, the quality of data varies by country—wealthy nations have better health tracking than poorer ones, which might affect the accuracy of some findings. The predictions to 2050 are based on patterns from the past, so unexpected changes could alter these forecasts.

What the Results Show

In 2021, vitamin A deficiency caused about 1.1 million years of lost health globally, which is a significant improvement from 1.97 million in 1990. This represents a 44% decrease over three decades. The rate of decline was about 2.8% per year on average. Men were affected more severely than women throughout the entire time period, though both groups showed improvement. The biggest impact was on children under 5 years old, who are most vulnerable to vitamin A deficiency. Wealthy countries saw the fastest improvements, with some reducing their burden by more than half. In contrast, poorer countries still carry a much heavier burden of vitamin A deficiency.

The research found that vitamin A deficiency is most common in regions with low socioeconomic development. Sub-Saharan Africa and South Asia carry the largest share of the global burden. The problem is closely linked to poverty, poor nutrition, and limited access to healthcare. Infections like measles and diarrhea make vitamin A deficiency worse and more dangerous. The study also found that progress has not been equal everywhere—some countries have made dramatic improvements while others have seen slower progress.

This research confirms what previous studies have shown: vitamin A deficiency is decreasing globally, but the progress is uneven. The findings align with the success of vitamin A supplementation programs that have been running in many countries. However, this study provides the most comprehensive global picture to date, showing that despite improvements, vitamin A deficiency remains a significant problem in developing countries. The research suggests that existing programs are working, but more needs to be done.

The study relies on data quality that varies significantly between countries. Wealthy nations have better health tracking systems, so their data is more accurate than data from poorer countries. Some regions have incomplete information, which could affect the overall estimates. The predictions to 2050 assume that current trends will continue, but unexpected changes (like new diseases, wars, or economic shifts) could alter these forecasts. The study cannot identify exactly why some countries improved faster than others, only that they did.

The Bottom Line

If you live in a wealthy country, vitamin A deficiency is unlikely to be a concern for you or your family if you eat a reasonably balanced diet. If you live in or work with communities in low-income countries, supporting nutrition programs and vitamin A supplementation efforts is important. Parents in developing regions should ensure children receive vitamin A supplements as recommended by health authorities. Healthcare workers should screen for vitamin A deficiency in high-risk populations.

Global health organizations, government health departments, and NGOs working in developing countries should prioritize vitamin A programs. Parents in low-income regions should be aware of the importance of vitamin A for their children’s health. Healthcare providers in areas with high deficiency rates should screen for and treat vitamin A deficiency. People interested in global health and nutrition should understand this as a major public health issue that still needs attention.

Vitamin A supplementation programs typically show benefits within weeks to months for preventing infections and supporting eye health. However, reversing severe vitamin A deficiency-related blindness takes longer and may not be fully reversible if damage is extensive. The global improvements shown in this study took place over 31 years, showing that large-scale change requires sustained effort and investment over decades.

Want to Apply This Research?

  • If you work in global health or nutrition, track the vitamin A supplementation coverage in your region or program monthly. Record the percentage of children under 5 who received vitamin A supplements and monitor changes in health outcomes like infection rates or eye health screenings
  • For individuals in at-risk areas: ensure regular consumption of vitamin A-rich foods (orange vegetables, leafy greens, liver, eggs, dairy) and follow local health authority recommendations for vitamin A supplementation. For health workers: implement or support vitamin A supplementation programs in your community and educate families about vitamin A importance
  • Track vitamin A status through regular health check-ups if you’re in a high-risk region. Monitor children’s eye health and infection frequency as indicators of adequate vitamin A status. For program managers, track supplementation coverage rates and health outcomes quarterly to ensure programs are reaching their targets and making a difference

This research provides important global health information but should not replace personalized medical advice. If you or your child have symptoms of vitamin A deficiency (such as night blindness, dry eyes, or frequent infections), consult a healthcare provider for proper diagnosis and treatment. Vitamin A supplementation should be done under medical guidance, especially for children, as excessive vitamin A can be harmful. This study analyzes population-level trends and cannot predict individual health outcomes. Always follow your local health authority’s recommendations regarding vitamin A supplementation and nutrition.