The Global Picture: A Look at the Numbers
While largely eradicated in developed countries, vitamin A deficiency (VAD) remains a significant and widespread public health concern in low- and middle-income countries (LMICs). Statistics paint a complex picture, with variations depending on the population group and measurement year. A comprehensive study published in 2023, analyzing data from 165 LMICs for the year 2019, estimated that 14.73% of the pediatric population (children and adolescents under 18) had a vitamin A deficiency. Breaking that down further, the prevalence was notably higher in younger age groups, with 19.53% of children aged 0-5 years being affected. Historical data from the World Health Organization (WHO) in 2013 showed an even higher estimate of 29% for children aged 6–59 months in LMICs. These figures, while showing a general downward trend in some areas due to intervention efforts, underscore that VAD continues to impact hundreds of millions globally.
Regional Differences in VAD Prevalence
Prevalence rates are not uniform across the globe but are heavily concentrated in certain regions, often correlating with the socio-demographic index (SDI). High-income nations report very low prevalence, typically below 1%. The burden is most severe in low-SDI regions, with significant disparities in prevalence and associated morbidities.
- Sub-Saharan Africa and South Asia: These regions consistently face the highest burden. A 2013 analysis reported prevalence rates for children 6–59 months at 48% in sub-Saharan Africa and 44% in South Asia. More recent data from 2019 indicates that sub-Saharan Africa still holds the highest prevalence, particularly in central sub-Saharan Africa.
- Middle East and North Africa (MENA): While the region saw a significant decline in VAD prevalence between 1990 and 2019, it still has a significant burden, especially in lower-SDI countries like Afghanistan and Yemen.
- Europe and North America: Prevalence is extremely low in these high-SDI regions, where dietary intake and fortification efforts are typically sufficient.
Populations at Highest Risk
Certain demographic groups are particularly vulnerable to vitamin A deficiency:
- Young Children: Infants and preschool-aged children are at high risk due to their rapid growth and higher susceptibility to infectious diseases, which can deplete their already limited vitamin A reserves. VAD is the leading cause of preventable childhood blindness worldwide.
- Pregnant and Lactating Women: Their nutritional needs are significantly increased, and deficiency can lead to complications such as night blindness and increased maternal mortality risk.
- Individuals with Malabsorption Disorders: People with conditions such as cystic fibrosis, celiac disease, or chronic diarrhea have impaired ability to absorb fat-soluble vitamins like vitamin A, regardless of their diet.
- Refugees and Displaced Populations: These groups often face severe food insecurity and are at a dramatically higher risk of VAD.
Causes, Consequences, and Interventions
The root cause of VAD is often inadequate dietary intake, particularly in regions where access to animal products (a rich source of preformed vitamin A) is limited and diets rely heavily on starchy staples. This issue is compounded by high rates of infectious diseases like measles and diarrhea, which exacerbate the deficiency.
Consequences range from mild to life-threatening. The earliest symptom is night blindness, which progresses to more severe eye conditions like xerophthalmia and potentially irreversible blindness. VAD also severely weakens the immune system, increasing vulnerability to infections and raising mortality rates in children.
Interventions include high-dose vitamin A supplementation (VAS), food fortification, and promoting dietary diversification. These efforts have been successful in reducing the global burden, especially related to mortality. However, sustaining these gains and reaching the most vulnerable populations remains a challenge, highlighting the continued need for targeted programs. For more details on the severity classifications, refer to the World Health Organization's nutrition data.
Comparison of VAD Prevalence Indicators Across Populations
| Population Group | Estimated Prevalence (approximate) | Notes |
|---|---|---|
| Children (0-5 years) in Low-SDI Regions | ~29.7% in 2019 | Public health significance is severe. |
| Children (0-5 years) in Sub-Saharan Africa | ~30.6% in 2019 | Highest prevalence among all WHO regions for this age group. |
| Children & Adolescents (0-18) in LMICs | ~14.7% in 2019 | Represents over 333 million individuals. |
| General Population in High-Income Countries | < 1% | Deficiency is very rare, typically linked to other health issues. |
| Pregnant Women in At-Risk Regions | Variable, often over 5% | Night blindness is a key clinical indicator in this group. |
Conclusion
What percentage of people have vitamin A deficiency? The answer is complex and highly dependent on geographic and demographic factors. While nearly eradicated in wealthy nations, VAD remains a profound issue in many low- and middle-income regions, where tens of millions of children and pregnant women are at risk. Statistics show significant prevalence in regions like Sub-Saharan Africa and South Asia, though overall global efforts have led to some reductions. Ongoing surveillance and targeted interventions are necessary to continue addressing this public health challenge effectively.
Symptoms of Vitamin A Deficiency
- Night blindness, or difficulty seeing in low light.
- Xerophthalmia, or severe dryness of the eyes.
- Foamy spots on the whites of the eyes, known as Bitot's spots.
- Corneal ulcers and eventual blindness if left untreated.
- Increased susceptibility to infections, particularly respiratory and diarrheal infections.
- Dry, scaly skin.
- Stunted growth and delayed development in children.
