More than half of the world’s population consumes inadequate levels of several micronutrients essential for health, including calcium, iron, and vitamins C and E, according to a new study by researchers at Harvard T.H. Chan School of Public Health, the University of California, 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 for human health.
The study will be published in The Lancet journal on global health on August 29th.
Micronutrient deficiencies are one of the most common forms of malnutrition worldwide, and each deficiency carries its own health consequences, from adverse pregnancy outcomes to blindness and increased susceptibility to infectious diseases. Previous research has estimated the amounts of micronutrients available and consumed by people; this study assesses whether these intakes meet recommended requirements for human health and looks at the deficiencies specifically faced by men and women throughout their lives.
“Our study is a major step forward,” said co-senior author Chris Free, a UCSB research professor. “Not only because it is the first to estimate micronutrient inadequacy for 34 age and 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 World Dietary Database, the World Bank, and dietary recall surveys in 31 countries to compare nutrient requirements with nutrient intake among populations in 185 countries (they have made these data, as well as the code for the analysis, freely available). They divided the populations into men and women in 17 age groups: zero to 80 years over five-year periods, as well as a group aged 80 years and older. The assessment looked at 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 significant deficiencies in intakes of nearly all micronutrients assessed, excluding fortification as a potential source of additional nutrients. Inadequate intakes were especially prevalent for iodine (68% of the world’s 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 sufficient, with 22% of the world’s population consuming inadequate levels, followed by thiamine (30%) and selenium (37%).
Inadequate intakes of iodine, vitamin B12, iron and selenium were estimated to be higher among women than among men, in the same country and age groups. In contrast, inadequate intakes of calcium, niacin, thiamine, zinc, magnesium and vitamins A, C and B6 were higher among men than among women. While patterns of micronutrient inadequacy emerged most clearly by sex, the researchers also found that men and women aged 10–30 years were most likely to have low calcium intakes, particularly in South and East Asia and sub-Saharan Africa. Calcium intakes were also low in North America, Europe and Central Asia.
“These results are alarming,” said Ty Beal, Senior Technical Specialist at GAIN. “The majority of people, even more than previously thought, in all regions and countries at all income levels, do not consume enough of multiple essential micronutrients. These deficiencies compromise health outcomes and limit human potential globally.”
“The public health challenge we face is immense, but practitioners and policymakers have an opportunity to identify the most effective dietary interventions and target them to the populations most in need,” added senior author Christopher Golden, an associate professor of nutrition and planetary health at Harvard Chan School of Health.
The researchers noted that a lack of available data, especially on individual dietary intake worldwide, may have limited their findings.
Simone Passarelli, a former PhD student and postdoctoral researcher in the Department of Nutrition at Harvard Chan School, was co-lead author. She received funding from the National Institutes of Health (training grant 2T32DK007703-26).