More than half the world's population faces micronutrient deficiencies, including inadequate levels of calcium, iron, and vitamins C and E, according to a recent study that provides the first global estimates of inadequate consumption of 15 micronutrients critical to human health.

Micronutrients are essential vitamins and minerals crucial for bodily functions such as growth, development, and immunity. Although the body needs these nutrients only in small amounts, deficiencies can have severe health consequences, ranging from adverse pregnancy outcomes and blindness to increased susceptibility to infectious diseases.

Previous studies have measured the availability and consumption of micronutrients among populations across the world. However, the latest study conducted by a research team from Harvard T.H. Chan School of Public Health, UC Santa Barbara (UCSB), and the Global Alliance for Improved Nutrition (GAIN) analyzed whether these intakes meet the recommended levels for human health. The researchers also looked at the specific deficiencies affecting males and females throughout different stages of life. The results were published in the journal The Lancet Global Health.

"Our study is a big step forward. 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," said co-lead author Chris Free, research professor at UCSB in a news release.

The study compared nutritional requirements with actual intake across populations in 185 countries using data from the Global Dietary Database, the World Bank, and dietary surveys from 31 countries. The researchers then grouped the population based on gender and divided them into 17 age categories, from newborns to those over 80, in five-year intervals.

The micronutrients covered in the study are calcium, iodine, iron, riboflavin, folate, zinc, magnesium, selenium, thiamin, niacin, and vitamins A, B6, B12, C, and E.

Significant inadequacies were found in nearly all of the micronutrients evaluated, with the most concerning being iodine (68% of the global population), vitamin E (67%), calcium (66%), and iron (65%). Additionally, more than half of the world's population showed deficiencies in riboflavin, folate, and vitamins C and B6.

However, the results were somewhat reassuring for certain micronutrients like niacin, which had the fewest deficiencies, with only 22% of the global population consuming inadequate levels, followed by thiamin (30%) and selenium (37%).

When comparing inadequate intake between genders, women were more deficient than men in iodine, vitamin B12, iron, and selenium within the same countries and age groups. However, men had higher rates of inadequate intake of calcium, niacin, thiamin, zinc, magnesium, and vitamins A, C, and B6. The study also found that both men and women in the 10-30 age group were particularly prone to low calcium intake.

"These results are alarming. 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," said Ty Beal, senior technical specialist at GAIN.

Read more