What is the most common vitamin deficiency worldwide?

December 30, 2025 •

3 min read

According to the World Health Organization (WHO), over two billion people suffer from some form of vitamin or mineral deficiency, a condition often referred to as "hidden hunger". While many deficiencies exist, one stands out as the most common and widespread globally, impacting billions across both developed and developing nations.

Quick Summary

The most common nutritional deficiency worldwide is iron, affecting billions of people and causing widespread anemia, particularly in women and children. Other prevalent deficiencies include vitamin A and vitamin D, but iron is the most prevalent global nutritional disorder.

Key Points

Iron is the Most Common: The most prevalent nutritional deficiency globally is iron, affecting billions, particularly in developing countries.
Anemia is a Major Consequence: Iron deficiency is the leading cause of anemia worldwide, leading to symptoms like fatigue and weakness.
Vulnerable Populations are at Highest Risk: Women of reproductive age, pregnant women, and young children are most susceptible to iron deficiency due to increased needs.
Hidden Hunger is Widespread: Many deficiencies, including vitamin A and D, are also common globally, contributing to a state of "hidden hunger".
Prevention Requires Multifaceted Approaches: Combating deficiencies involves food fortification, targeted supplementation, and improving overall dietary diversity through education.
Symptoms are Not Always Specific: The signs of deficiencies can be vague, but long-term effects can include developmental delays, increased infection risk, and other serious health complications.

Iron Deficiency: The Most Common Deficiency Globally

Iron deficiency is the most prevalent nutritional disorder in the world, affecting an estimated two billion people. This condition is particularly widespread among vulnerable populations, including young children, women of reproductive age, and pregnant women. The World Health Organization (WHO) reports that iron deficiency is the leading cause of anemia, a condition where there is a reduced number of red blood cells, causing fatigue, weakness, and other health issues.

Causes of Iron Deficiency

Insufficient iron intake is a primary driver, especially in low- and middle-income countries where diverse, iron-rich diets are often unavailable. However, the problem also persists in industrialized nations due to varying factors.

Dietary Iron Bioavailability: The body absorbs heme iron, found in animal products, more efficiently than non-heme iron from plant-based sources. Diets heavy in grains and legumes can also contain phytates, which inhibit iron absorption.
Increased Demand: Women of childbearing age, particularly during pregnancy, require significantly more iron to support both their own and their fetus's needs. Children also have high iron requirements during periods of rapid growth.
Blood Loss: Heavy menstruation in women is a common cause of iron loss, while chronic gastrointestinal bleeding from conditions like ulcers or parasitic infections can also contribute significantly.
Malabsorption: Digestive disorders, such as inflammatory bowel disease or celiac disease, can impair the body's ability to absorb iron from food.

Consequences and Symptoms

The impacts of iron deficiency, particularly iron deficiency anemia, can be severe and far-reaching.

Fatigue and Weakness: Persistent and unexplained tiredness is one of the most common symptoms, severely impacting quality of life and productivity.
Cognitive and Developmental Impairment: In children, iron deficiency can affect neurodevelopment, leading to behavioral disturbances and developmental delays.
Increased Vulnerability to Infection: Iron is crucial for a healthy immune system, and a deficiency can increase susceptibility to illness.
Pregnancy Complications: For pregnant women, a deficiency raises the risk of preterm delivery and low birth weight.

Other Prevalent Micronutrient Deficiencies

While iron is the most widespread, other vitamin and mineral deficiencies also affect a significant portion of the global population. Vitamin A and Vitamin D are among the most notable.

Vitamin A Deficiency

Primarily an issue in low-income settings, vitamin A deficiency is the leading cause of preventable childhood blindness and increases the risk of serious infections. The WHO estimates that about 190 million preschool-age children suffer from it.

Vitamin D Deficiency

Often called the "sunshine vitamin," vitamin D deficiency is common worldwide, affecting approximately one billion people globally. Lack of sun exposure, as well as cultural and lifestyle factors, contribute significantly to this deficiency in both sunny and less-sunny regions.

Comparison of Common Deficiencies


Deficiency	Global Prevalence	High-Risk Populations	Primary Symptoms	Key Intervention
Iron Deficiency	~2 billion individuals	Women of reproductive age, children, pregnant women	Fatigue, weakness, anemia, developmental delays	Dietary improvements, iron supplementation, addressing blood loss
Vitamin A Deficiency	~190 million preschool children	Preschool children, pregnant women	Night blindness, visual impairment, increased infection risk	Vitamin A supplementation, dietary diversity
Vitamin D Deficiency	~1 billion individuals	Older individuals, institutionalized, low sun exposure populations	Osteomalacia (adults), rickets (children), increased infection risk	Sun exposure, fortified foods, supplementation

Prevention and Management

Combating widespread nutritional deficiencies requires multi-faceted strategies, from public health initiatives to personal dietary adjustments. Interventions can include:

Fortification of Foods: Adding essential micronutrients to staple foods like flour, salt, and milk can help reach large populations.
Supplementation Programs: Targeted vitamin A supplementation for children and iron-folic acid for pregnant women are effective strategies.
Nutrition Education: Promoting dietary diversity and awareness of nutrient-rich foods, especially in vulnerable communities.
Addressing Underlying Health Issues: For iron deficiency, it is vital to treat conditions that cause chronic blood loss, such as parasitic infections.

Conclusion

While several micronutrient deficiencies are significant global public health concerns, iron deficiency stands out as the most common worldwide, affecting a vast and diverse population. Its impact, particularly through anemia, poses serious risks, especially for women and children. The prevalence of other deficiencies, such as vitamin A and D, highlights the need for continued global health efforts. Combating these issues requires a combination of widespread food fortification, targeted supplementation, and comprehensive nutrition education to ensure better health outcomes for billions of people across the globe.

International Journal of Clinical Biochemistry and Research on IDA in India

Frequently Asked Questions

While iron is technically a mineral, iron deficiency is widely recognized as the most common nutritional deficiency overall, affecting approximately two billion people globally. Among vitamins, deficiencies in Vitamin A and Vitamin D are highly prevalent.

Women of reproductive age, pregnant women, and young children are the highest-risk groups for iron deficiency. These groups have greater iron needs due to menstruation, pregnancy, and periods of rapid growth.

The most common consequence is anemia, which can cause fatigue, weakness, and impaired cognitive and physical performance. In children, it can also lead to developmental delays.

Prevention strategies include dietary changes to include more iron-rich foods (especially animal products), food fortification programs, and iron supplementation for at-risk individuals, such as pregnant women.

Yes, Vitamin A deficiency remains a significant public health issue, particularly in low-income countries. It is the leading cause of preventable childhood blindness and increases the risk of childhood infections.

Insufficient exposure to sunlight is the primary cause, as the body produces Vitamin D when exposed to UV-B rays. Other factors include geographical location, skin pigmentation, age, and dietary insufficiency.

"Hidden hunger" is a term used to describe micronutrient deficiencies, which include deficiencies in both essential vitamins and minerals like iron. So, while not exactly the same, vitamin deficiency is a key component of hidden hunger.