More than half of the world's population is deficient in micronutrients

Global modeling by American scientists has shown that more than five billion people do not consume enough iodine, vitamin E and calcium from food. More than four billion people do not consume enough iron, riboflavin, folic acid and vitamin C. The results of the study are published in The Lancet Global Health.

Micronutrient deficiencies are considered one of the most common forms of malnutrition worldwide. The main cause of micronutrient deficiency remains inadequate intake of key nutrients such as iron, zinc, vitamin A, iodine and folic acid, with deficiencies in each nutrient having different public health implications.

For example, iron deficiency anemia is the most common form of anemia, and vitamin A deficiency leads to blindness. Folic acid is essential in early pregnancy to reduce the risk of stillbirth and neural tube defects, and iodine is necessary for pregnant and lactating women for normal fetal development. Therefore, deficiencies of these and other micronutrients together lead to a significant increase in morbidity and mortality. However, the extent and demographics of the problem are unknown due to a lack of data.

A team of scientists led by Simone Passarelli of Harvard University, using modeling and national data, estimated the global prevalence of inadequate micronutrient intake by accounting for the distributional patterns of nutrient intake and using globally agreed upon reference values.

The global analysis showed that 5.1 billion people (68 per cent of the world's population) are deficient in iodine, with almost the same proportion of people being vitamin E deficient. Calcium came in third place, with an estimated five billion people (66 percent of the population; the highest levels were found in South Asia, sub-Saharan Africa and East Asia). Notably, iron deficiency came in fourth place with 4.9 billion people (65 percent of the population). People were least likely to be deficient in niacin (1.7 billion people, 22 percent of the population), followed by thiamine (2.2 billion people, 30 percent of the population) and magnesium (2.4 billion people, 31 percent).

Several countries showed inadequate intakes that differed from the overall figures. For example, in India, estimated inadequate intakes of riboflavin, folic acid, vitamin B6 and vitamin B12 were particularly high. Madagascar and the Democratic Republic of the Congo had high levels of niacin underconsumption; and Russia, Mongolia and Kazakhstan had high levels of selenium underconsumption.

Globally, the prevalence of inadequate intakes of iodine, vitamin B12, iron and selenium was consistently higher among women than among men in the same country and age group. Meanwhile, the prevalence of inadequate intake of magnesium, vitamin B6, zinc, vitamin C, vitamin A, thiamine and niacin was consistently higher in men than in women in the same country and age group.

According to the authors, this is the first such global assessment of inadequate micronutrient intake worldwide and among different population groups. In the future, the results of this study may be useful for public health professionals to address micronutrient malnutrition.