Final answer:
A substantial portion of the population is deficient in at least one micronutrient, with iron deficiency being the most common, affecting approximately 2 billion people. Malnutrition, including micronutrient deficiencies, is widespread, especially in low- and middle-income countries, and contributes to a range of health issues.
Step-by-step explanation:
Roughly, a significant portion of people are deficient in at least one micronutrient. Iron is the single most common micronutrient deficiency globally, affecting about 2 billion people, which translates to a substantial number but not one easily distilled into a precise percentage of the global population. However, we know malnutrition, which includes micronutrient deficiencies, is widespread particularly in low- and middle-income countries. Many people, including children, suffer from inadequate intake of essential vitamins and minerals, leading to significant health issues such as anemia, cognitive deficits, and poor growth.
Iron deficiency alone is an excellent example of how critical micronutrients are, causing anemia, particularly in women and children under five. Anemia linked to iron deficiency can lead to increased mortality in infancy and poor cognitive and motor development in early childhood. Other common deficiencies include vitamin A and iodine, which have severe implications such as weakened immune systems, blindness, and intellectual disability, respectively.