A well-rounded diet is critical for the body’s overall growth, strengthening immunity, and supplying the nutrients required for optimum health; yet, many people do not obtain enough important vitamins and minerals from their food and beverages. More than half of the global population consumes inadequate levels of several micronutrients essential to health, including calcium, iron, and vitamins C and E, according to a new study by researchers at Harvard TH Chan School of Public Health, UC Santa Barbara (UCSB), and the Global Alliance for Improved Nutrition (GAIN). 

It is the first study to provide global estimates of inadequate consumption of 15 micronutrients critical to human health. The study was published in The Lancet Global Health on August 29.

“Our study is a big step forward,” said co-lead author Chris Free, research professor at UCSB. “Not only because it is the first to estimate inadequate micronutrient intakes for 34 age-sex groups in nearly every country, but also because it makes these methods and results easily accessible to researchers and practitioners.”

The researchers used data from the Global Dietary Database, the World Bank, and dietary recall surveys in 31 countries to compare nutritional requirements with nutritional intake among the populations of 185 countries. (They have made these data, as well as code for analysis, freely available.) They divided populations into males and females belonging to17 age groups: zero to 80 in five-year spans, as well as an 80+ group. The assessment studied fifteen vitamins and minerals: calcium, iodine, iron, riboflavin, folate, zinc, magnesium, selenium, thiamin, niacin, and vitamins A, B6, B12, C, and E.

The study found significant intake inadequacies for nearly all of the evaluated micronutrients, excluding fortification as a potential source of additional nutrients. Inadequate intake was especially prevalent for iodine (68% of the global population), vitamin E (67%), calcium (66%), and iron (65%). More than half of people consumed inadequate levels of riboflavin, folate, and vitamins C and B6. Intake of niacin was closest to sufficient, with 22% of the global population consuming inadequate levels, followed by thiamin (30%) and selenium (37%).