The discovery of vitamins a little over one century ago was incredibly important for the field of nutrition (1). At last, we had found the key to preventing vitamin deficiencies! Knowing about the vitamins meant that medical questions that had puzzled humans for centuries – why does fresh citrus fruit cure scurvy, but a syrup made from the juice does not? – could be reliably answered (2). Despite this grand leap in the understanding of nutrition, however, vitamin and mineral deficiencies still plague us around the globe. While we know in general which micronutrients and how much most people need to stay healthy, making sure that everyone has access to micronutrients is more problematic. Each region in the world has its own nutrition concerns. The problem of “hidden hunger,” when people may get enough calories but the micronutrient content of their diet is lacking, is improving but there is still a long way to go (3). Which micronutrient deficiencies are found throughout the world?
South Asia, East Asia and the Pacific
South Asia, East Asia and the Pacific, comprising countries such as China, Indonesia, Vietnam, India, Bangladesh and Malaysia, have mostly showed a large improvement in micronutrient status in their population over the past decades (3). General programs to support economic growth have raised the standard of living for many people living in developing Asian countries, and staple food fortification has been able to reduce specific micronutrient deficiencies such as iodine and iron. Despite these gains, deficiencies in iron and vitamin A are still prevalent in some risk groups: 27 million school age children, 7.5 million pregnant women and 96 million non-pregnant women in the region are affected by anemia, while 13 percent of pre-school children and 21 percent of pregnant women are affected by vitamin A deficiency (4).
Eastern Europe and Central Asia
Low- and middle-income countries in Europe and Central Asia have shown a modest improvement in reducing micronutrient deficiencies (3). In this region, however vitamins A and D, iodine, iron, zinc, folate and thiamine are marked as micronutrients of special concern (5). The rates of deficiencies vary depending on the country, as local laws, the economic situation, cultural trends and the environment can affect supply of vitamins and minerals. In particular, iodine deficiency in central Europe is common, and is very much impacted by national policies regarding iodine fortification (6). Seasonable variations in the availability of different foods can affect dietary intakes and nutrient status in Europe. For example, more fruits and vegetables are eaten in the summer and autumn months, leading to a better folate status in the general population in Slovakia (7). Certain vulnerable populations are at greater risk of micronutrient deficiency. These groups include pregnant women and young children, the elderly, people with a low socioeconomic status, and those affected by chronic disease (8-10).
Latin America and the Caribbean
Micronutrient nutrition in Latin American and the Caribbean has improved in the past few years, and rates of deficiency tend to be the lowest of the low- and middle-income countries (3). In fact, all countries in this area of the world reduced their prevalence of hidden hunger in the period 1995-2011 (3). Despite these relative improvements, micronutrient deficiencies have an impact on health for a significant proportion of people in this area of the world. Iron deficiency anemia and zinc deficiency remain a problem for women of childbearing age and children aged under 6 years (11, 12). While vitamin B12 deficiency is not monitored as well as other micronutrients, an incidence greater than 10 percent is reported for vulnerable groups in some countries, such as women aged 13 to 49 in Colombia, and children aged 6 months to 5 years in Guatemala. Rates of vitamin and mineral deficiencies can vary greatly between countries. For example, vitamin A deficiency in young children has been virtually eradicated in Guatemala and Nicaragua, yet is a severe public health problem in Colombia, Mexico, and Haiti (13).
One micronutrient success story has been the use of folic acid fortification to improve folate status and reduce the occurrence of neural tube defects in Latin American and the Caribbean. The introduction of mandatory folic acid fortification for almost all countries has led to a dramatic reduction in the percentage of the population with folate deficiency (14). In turn, surveillance of neural tube defects shows a decrease of one- to two-thirds compared to the pre-fortification period (15). Carefully designed interventions such as staple food fortification, and that focus on vulnerable groups, are needed to further improve micronutrient nutrition in Latin America and the Caribbean (12).
Middle East and North Africa
The nutrition situation in the Middle East and North Africa has improved substantially in the last decades. Many countries are undergoing an advanced nutrition transition, whereby there is a modest reduction in micronutrient malnutrition, while rates of overweight and obesity are rapidly increasing (16). Unfortunately, the complex security situation in several countries (Afghanistan, Libya, Somalia, Sudan, and Syria) has further increased food insecurity, leading to widespread acute and chronic under nutrition, especially in young children and pregnant women (16).
The vitamins and minerals most often found to be deficient in nutritional surveys in the region include calcium, iodine, iron, vitamin A, vitamin D, and folate (16). Food fortification programs in the area are patchy, and while many countries have dietary guidelines for individuals that promote a healthful diet, their uptake has been limited (16). Anemia is the most prevalent micronutrient deficiency in the Middle East, and can affect more than half of some countries. Vitamin D deficiency has been reported for many countries despite plentiful sunshine; this relates to few dietary sources and wearing traditional clothing that blocks sunlight from reaching the skin.
Several countries including Jordan, Egypt, the United Arab Emirates, Oman and Kuwait have mandatory wheat flour fortification policies in place. All these countries fortify with folic acid and iron, and some include zinc and other vitamins as well. However, rice and maize are also staple foods in these countries and are not fortified, hence micronutrient deficiencies remain widespread despite the existence of fortification.
West, Central and Sub-Saharan Africa
The majority of countries showing an increase in hidden hunger over the past years were located in West, Central and Southern Africa. These results do not bode well for the social and economic development in countries affected by a high prevalence of under nutrition (3). The causes of micronutrient deficiencies in Africa are multi-factorial and relate to poor economic development, unstable governments that neglect critical investments into education, health and infrastructure, and food insecurity related to harsh agricultural environments (17). The high prevalence of vitamin and mineral deficits, such as iron deficiency anemia, zinc deficiency and vitamin A deficiency will only be reduced when the underlying causes of poverty are alleviated.
In some countries in southern Africa, commitment to improving the nutritional status of the population has shown positive results. For example, a mandatory fortification program for maize and wheat flour in South Africa has been effective in improving vitamin and mineral intakes (18, 19). There is still room for improvement in South Africa, however; it is one of 48 countries worldwide prioritized as having an “unfinished fortification” program (20).
While developing countries bear the greatest burden of micronutrient deficiencies around the world, they still exist in high-income countries. The considerable resources of high-income countries mean that the micronutrient status of their populations is studied in greater detail than the rest of the world and give a better estimate of the true rate. Comprehensive a representative analyses of U.S. populations find that 5 percent or more is affected by deficiencies in vitamins B6, C and D, and almost 10 percent of women of child-bearing age are affected by low body iron (21). In Europe, international comparisons find that at least half of certain population groups do not meet recommendations. Intakes of thiamine in Italian women, B6 in women from many countries, and vitamin C in Scandinavian men and male smokers are clearly too low (22, 23). Also, intakes of both vitamin D and E are low for most people living in Northern, Western and Southern Europe (22, 23). A lack of education about nutrient-dense diets and poor food choices are a major contributor to micronutrient deficiencies in high-income countries.