Funded by the National Institutes of Health and the Dutch Ministry of Foreign Affairs, the work was led by researchers from the Harvard T.H. Chan School of Public Health, UC Santa Barbara and the Global Alliance for Improved Nutrition.
“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,” said Christopher Golden, senior author on the paper and associate professor of nutrition and planetary health at Harvard T.H. Chan School.
While assessments over the past 10 years have explored global micronutrient deficiencies and inadequate nutrient supplies, the researchers noted that large data gaps remain for many micronutrients and population groups.
“This analysis represents, to our knowledge, the first estimate of inadequate micronutrient intakes globally and across diverse subpopulations, and we have made our code and underlying data publicly available so that others can use and build upon these results,” they wrote.
Identifying dietary nutrient gaps
In what the researchers described as a novel approach, the analysis drew on data from the Global Dietary Database, the World Bank and dietary recall surveys in 31 countries to account for the shape of a population's nutrient intake distribution.
“Using a globally harmonized set of age-specific and sex-specific nutrient requirements, we then applied these distributions to publicly available data from the Global Dietary Database on modelled median intakes of 15 micronutrients for 34 age–sex groups from 185 countries, to estimate the prevalence of inadequate nutrient intakes for 99.3% of the global population.”
Vitamins and minerals assessed included calcium, iodine, iron, riboflavin, folate, zinc, magnesium, selenium, thiamin, niacin and vitamins A, B6, B12, C and E.
“On the basis of estimates of nutrient intake from food (excluding fortification and supplementation), more than 5 billion people do not consume enough iodine (68% of the global population), vitamin E (67%) and calcium (66%),” the study reported. “More than 4 billion people do not consume enough iron (65%), riboflavin (55%), folate (54%) and vitamin C (53%).”
Intake of niacin was closest to sufficient, with 22% of the global population consuming inadequate levels, followed by thiamin (30%) and selenium (37%).
Within the same country and age groups, the analysis found that estimated inadequate intakes were higher for women than for men for iodine, vitamin B12, iron and selenium and higher for men than for women for magnesium, vitamin B6, zinc, vitamin C, vitamin A, thiamin and niacin.
While patterns of micronutrient inadequacy were more clearly defined by sex, both males and females between the ages of 10 and 30 were most susceptible to low levels of calcium intake, especially in South and East Asia and sub-Saharan Africa. Calcium intake was also low across North America, Europe, and Central Asia. Prevalence of inadequate intake of iodine, vitamin E, riboflavin and vitamin B12 also varied across regions.
Ty Beal, co-author on the paper and senior technical specialist at the Global Alliance for Improved Nutrition, described the results as alarming.
“Most people—even more than previously thought, across all regions and countries of all incomes—are not consuming enough of multiple essential micronutrients,” he said. “These gaps compromise health outcomes and limit human potential on a global scale.”
Excluding fortification and supplementation
The estimates did not include information on fortification or supplementation, which the researchers noted are uncommon globally but contribute to an overestimated risk for some key nutrients such as iodine in particular locations.
Data shared indicated that supplementation for selected demographic groups (pregnant women and young children) is somewhat common for iron and that the proportion of supplementation is highest for vitamin A in children between 6 and 59 months.
The researchers highlighted that understanding the patterns of inadequate micronutrient intake will make it possible to identify where dietary interventions, biofortification, fortification and supplementation are needed.
“Moreover, examining which nutrient intake inadequacies are correlated with each other could help to determine which nutritional responses need to be coordinated to improve the efficiency of intervention delivery,” they added. “Particular geographies warrant further investigation into the causes and severity of deficiencies before adopting fortification, supplementation, and dietary intervention policies.”
Source: The Lancet Global Health
doi: 10.1016/S2214-109X(24)00276-6
“Global estimation of dietary micronutrient inadequacies: a modelling analysis”
Authors: Simone Passarelli et al.