Billions of people worldwide consume insufficient levels of micronutrients essential for human health, new study finds

More than half of the world’s population does not consume enough micronutrients essential for 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). This is the first study to provide global estimates of inadequate consumption of 15 micronutrients essential for human health.

The study is published in The Lancet journal on global health newspaper.

Micronutrient deficiencies are one of the most common forms of malnutrition worldwide. Each deficiency has its own health consequences, ranging from pregnancy complications to blindness and increased susceptibility to infectious diseases. Previous research has estimated the amounts of micronutrients available and consumed by individuals. This study assesses whether these intakes meet recommended requirements for human health and examines the deficiencies that specifically affect men and women throughout their lives.

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

The researchers used data from the Global Dietary Database, the World Bank, and dietary recall surveys conducted in 31 countries to compare the nutritional needs and nutrient intakes of populations in 185 countries. (They made the data, along with the analysis code, freely available.) They divided the populations into men and women in 17 age groups: ages 0 to 80 over five-year periods, plus a group of ages 80 and older. The assessment included 15 vitamins and minerals: calcium, iodine, iron, riboflavin, folate, zinc, magnesium, selenium, thiamine, niacin, and vitamins A, B6, B12, C, and E.

The study found significant intake deficiencies for almost all micronutrients assessed, excluding fortification as a potential source of additional nutrients. Intake deficiencies were particularly common 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. Niacin intake was closest to adequacy, with 22% of the global population consuming inadequate levels, followed by thiamine (30%) and selenium (37%).

Estimated inadequate intakes were higher among women than men for iodine, vitamin B12, iron and selenium in the same countries and age groups. Conversely, men were more likely than women to consume inadequate levels of calcium, niacin, thiamine, zinc, magnesium and vitamins A, C and B6.

While patterns of micronutrient deficiency emerged more clearly by gender, the researchers also observed that men and women aged 10 to 30 years were most prone to low levels of calcium intake, particularly in South and East Asia and sub-Saharan Africa. Calcium intake was also low in North America, Europe and Central Asia.

“These findings are alarming,” said Ty Beal, senior technical specialist at GAIN. “Most people – more than previously thought, in every region and country, and across income levels – are not getting enough essential micronutrients. These deficiencies are compromising health outcomes and limiting human potential on a global scale.”

“The public health challenge we face is immense, but practitioners and policy makers have an opportunity to identify the most effective dietary interventions and target them to the populations that need them most,” added lead author Christopher Golden, associate professor of nutrition and planetary health at Harvard Chan School.

The researchers noted that the lack of available data, particularly on individual dietary intake across the world, may have limited their conclusions.

Simone Passarelli, a former doctoral student and postdoctoral researcher in the Department of Nutrition at the Harvard Chan School, was co-lead author.