The nutrients most often short worldwide
A handful of micronutrient shortfalls account for much of the global burden. Iron deficiency is the most widespread and the leading cause of anemia. Vitamin D insufficiency is common across many regions, driven by limited sun exposure. Vitamin B12, iodine, zinc, and vitamin A deficiencies remain significant, and marginal magnesium intake is frequent in diets high in refined foods.
Prevalence varies enormously by region, diet, and food fortification policy, so a single global figure for any one nutrient can be misleading.
Who tends to be most at risk
Risk clusters in predictable groups. Menstruating women, young children, and pregnant people are most exposed to iron deficiency. Vitamin A and zinc deficiencies hit children in lower-income settings hardest. Older adults and people on plant-only diets are more prone to B12 shortfall, and iodine risk depends heavily on whether local salt is iodized.
This is general educational information, not medical advice. Confirming a suspected deficiency calls for testing and professional interpretation rather than self-diagnosis from symptoms.