October 26, 2024, 2:04 pm | Read time: 5 minutes
It’s a wake-up call for global health: the results of a recently published Harvard study reveal that billions of people worldwide are consuming insufficient amounts of micronutrients that are important for good health. FITBOOK nutrition expert Sophie Brünke reports on which nutrients are involved.
The first study to provide global estimates of inadequate intakes of key vitamins and minerals has recently been published. A consortium of scientists from the Harvard T. H. Chan School of Public Health and the Global Alliance for Improved Nutrition (GAIN) set out to estimate the global prevalence of deficiencies of 15 essential micronutrients and to identify these gaps in nutrition in specific demographic groups and countries. Micronutrient deficiencies are among the most common forms of malnutrition worldwide – and each of these deficiencies has specific health consequences. They range from negative effects on pregnancy outcomes to blindness and increased susceptibility to infectious diseases. Four key nutrients were identified in the examination of nutrient deficiency in the global population.
Overview of the study
How did the scientists proceed?
On the one hand, the scientists used data from the Global Dietary Database, a database that uses nationally representative surveys to estimate global nutritional status. On the other hand, they used information from the World Bank and from nutrition surveys in 31 countries. On this basis, they compared the nutrient requirements with the nutrient intake of 99.3 percent of the world’s population in 185 countries.1
The research team also divided the population into men and women from 17 age groups: Zero to 80 years in five-year spans, as well as a group over 80. The assessment looked at 15 vitamins and minerals:
- Calcium,
- Iodine,
- Iron,
- Riboflavin,
- Folic acid,
- Zinc,
- Magnesium,
- Selenium,
- Thiamine,
- Niacin,
- Vitamin A,
- Vitamin B6,
- Vitamin B12,
- Vitamin C and
- Vitamin E.
Particularly exciting for scientists, experts, and interested parties: all data and the analysis code are free and freely accessible.
There is a nutrient deficiency in four vitamins and minerals in the global population
Almost all of the micronutrients examined showed significant deficiencies in intake. However, the researchers ruled out food fortification as a possible source of additional nutrients. The nutrient deficiencies of iodine, vitamin E, calcium, and iron were particularly serious and occurred in over half of the world’s population. More precisely, 68 percent (i.e., 5.1 billion people) were deficient in iodine, closely followed by vitamin E at 67 percent (5 billion people), calcium at 66 percent (5 billion people), and finally, iron at 65 percent (4.9 billion people).
However, more than half of people also did not consume enough riboflavin, folic acid, or vitamins C and B6. Niacin fared best in comparison, although 22 percent of the world’s population still consumed insufficient amounts. Thiamine (30 percent) and selenium (37 percent) were also at the lower end of the requirement range.
Regional and gender-specific differences
The study found that women within the same countries and age groups were more frequently affected by iodine, vitamin B12, iron, and selenium deficiencies than men. The latter, in turn, were more frequently deficient in calcium, niacin, thiamine, zinc, magnesium, and vitamins A, C, and B6. The gender-specific differences in nutrient deficiencies were particularly evident in the age groups between ten and 30 years.
The authors emphasized the low calcium intake as a particular cause for concern. This affects both sexes between the ages of ten and 30 worldwide. Regionally, this deficiency is particularly prevalent in South and East Asia and sub-Saharan Africa. However, even in economically more developed regions such as North America, Europe, and Central Asia, the calcium supply was often inadequate.
Scientists sound the alarm
Ty Beal, Senior Technical Specialist at GAIN, emphasizes in a press release: “These findings are alarming. Most people – even more than previously thought, in all regions and countries across all income groups – are not consuming enough of several essential micronutrients. These gaps affect health and limit human potential on a global scale.”2
Lead author Christopher Golden of Harvard Chan School adds: “The public health challenges we face are enormous, but practitioners and policymakers have the opportunity to identify the most effective nutrition interventions and target them to the populations that need them most.”
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Classification of the study
The scientists point out that their findings may have been limited by a lack of available data, primarily on individual dietary intake worldwide. Although the data basis has become more precise over time, nationally representative quantitative data on food intake over the past ten years is rare.
Furthermore, the study does not take into account any data on fortification or food supplements. This means that estimates of nutrient deficiency are likely to overestimate the risk for some key nutrients (e.g., iodine) in certain parts of the world. For example, the scientists state that, according to UNICEF, an estimated 89 percent of the world’s population consumes iodized salt. The serious iodine deficiency identified could, therefore, be an overestimate. However, food supplements and the fortification of foods with many other micronutrients are not common worldwide.
A further limitation is that – with the exception of iron and zinc – no interactions between the various nutrients or bioavailability could be taken into account.
Finally, it should be noted that co-lead author Simone Passarelli received financial support from the National Institutes of Health.