A new study by researchers from the Harvard T.H. Chan School of Public Health, the University of California, Santa Barbara (UCSB), and the Global Alliance for Improved Nutrition (GAIN) has found that over half of the world’s population is deficient in multiple micronutrients essential for health, including calcium, iron, vitamin C, and vitamin E. Micronutrient deficiencies are one of the most common forms of malnutrition globally, with each deficiency leading to specific health consequences—ranging from adverse pregnancy outcomes to blindness and increased susceptibility to infectious diseases.
The researchers used global dietary databases, World Bank data, and dietary recall surveys from 31 countries to compare the nutrient requirements and intakes of populations in 185 countries. They categorized the population into 17 age groups for both males and females: from 0 to 80 years old, in 5-year increments, and an 80+ group. They assessed 15 vitamins and minerals: calcium, iodine, iron, riboflavin, folate, zinc, magnesium, selenium, thiamin, niacin, and vitamins A, B6, B12, C, and E.
The study found that intakes of nearly all assessed micronutrients were severely deficient—excluding fortified foods as an additional source of nutrients. Deficiencies in iodine (68%), vitamin E (67%), calcium (66%), and iron (65%) were particularly widespread. More than half of the population had inadequate intakes of riboflavin, folate, vitamin C, and vitamin B6. Niacin intake was closest to adequate (22%), followed by thiamin (30%) and selenium (37%).