More than half of the global population consumes inadequate levels of essential micronutrients, such as calcium, iron, and vitamins C and E, according to a new study.

The research, conducted by Harvard T.H. Chan School of Public Health, UC Santa Barbara (UCSB), and the Global Alliance for Improved Nutrition (GAIN), suggests that micronutrient deficiencies may be more severe and varied between genders than previously thought.

Published in “The Lancet Global Health”, the study is the first to provide global estimates of inadequate consumption of 15 micronutrients critical to human health. These deficiencies are among the most common forms of malnutrition, leading to severe health consequences such as adverse pregnancy outcomes, blindness, and heightened susceptibility to infectious diseases.

“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 study used data from the Global Dietary Database, the World Bank, and dietary recall surveys in 31 countries, assessing the nutritional intake of populations across 185 countries. The researchers divided these populations into males and females across 17 age groups, ranging from birth to over 80 years old.

Significant inadequacies were found for nearly all evaluated micronutrients. Iodine intake was insufficient for 68% of the global population, vitamin E for 67%, calcium for 66%, and iron for 65%. More than half of the population also consumed inadequate levels of riboflavin, folate, and vitamins C and B6.

Inadequate intakes were particularly high among women for iodine, vitamin B12, iron, and selenium. Conversely, more men had insufficient levels of calcium, niacin, thiamin, zinc, magnesium, and vitamins A, C, and B6 compared to women. The study also highlighted that individuals aged 10-30, particularly in South and East Asia and sub-Saharan Africa, were most prone to low calcium intake.

“These results are alarming,” said Ty Beal, senior technical specialist at GAIN. “Most people—even more than previously thought, across all regions and countries of all incomes—are not consuming enough of multiple essential micronutrients. These gaps compromise health outcomes and limit human potential on a global scale.”

Senior author Christopher Golden, associate professor of nutrition and planetary health at Harvard Chan School, added, “The public health challenge facing us is immense, but practitioners and policymakers have the opportunity to identify the most effective dietary interventions and target them to the populations most in need.”

The researchers cautioned that a lack of data on individual dietary intake worldwide might have limited their findings, underscoring the need for more comprehensive data collection in future research.