Micronutrient Vitamins and Minerals
Micronutrients are the vitamins and minerals that the human body requires in small quantities to support metabolism, growth, immune function, and the maintenance of tissues. Unlike the energy-yielding macronutrients, they supply no calories; instead they act largely as cofactors, coenzymes, antioxidants, and structural or signalling elements. This area orients the reader to how vitamins and minerals are classified, why their requirements are measured in milligrams or micrograms, and why their deficiency remains a major global health concern.
Definition
Micronutrients are essential dietary vitamins and minerals required in small amounts (typically milligram or microgram quantities per day) that the body generally cannot synthesise in adequate amounts and that are necessary for normal physiological function.
Scope
The area covers the two broad vitamin classes (fat-soluble and water-soluble), the dietary minerals and trace elements, and the cross-cutting concepts of requirement-setting, bioavailability, and deficiency. It frames micronutrients as a reference and educational subject within human nutrition. It does not provide dosing, supplementation regimens, or individualized clinical advice.
Sub-topics
Core questions
- How are micronutrients classified and how does that classification relate to how the body stores and excretes them?
- How are human requirements for vitamins and minerals established and expressed?
- What determines whether an ingested micronutrient is actually absorbed and used (bioavailability)?
- What are the population-level consequences of micronutrient deficiencies?
Key concepts
- Essentiality and the concept of a dietary requirement
- Fat-soluble versus water-soluble vitamins
- Macrominerals and trace elements
- Dietary Reference Intakes and recommended intakes
- Bioavailability and nutrient-nutrient interactions
- Deficiency, marginal status, and toxicity (upper limits)
- Coenzyme, cofactor, and antioxidant roles
Mechanisms
Vitamins and minerals act through a small number of recurring molecular roles. Many B-group vitamins serve as coenzymes in intermediary metabolism; fat-soluble vitamins act in vision, calcium homeostasis, antioxidant defence, and blood clotting; and minerals function as enzyme cofactors, components of structural tissue such as bone, electrolytes, or constituents of metalloproteins. Because each nutrient participates in defined biochemical reactions, inadequate intake produces characteristic functional consequences, while the body's capacity to store some micronutrients (notably the fat-soluble vitamins) but not others shapes how quickly deficiency develops. A recurring theme is that micronutrients act in concert, supporting integrated functions such as immune defence rather than in isolation.
Clinical relevance
Understanding micronutrients underpins the interpretation of nutritional status, the rationale for food fortification and public-health programmes, and the appraisal of evidence on diet and disease. This entry describes how micronutrient adequacy and deficiency are conceptualised at a reference level; it is not a guide to diagnosing deficiency or prescribing supplements for an individual.
Epidemiology
Micronutrient deficiencies, sometimes called hidden hunger, affect a large share of the world's population, with the heaviest burden among young children and women of reproductive age in low- and middle-income settings. Pooled survey analyses estimate that micronutrient deficiencies are common even among apparently healthy populations, and undernutrition including micronutrient deficiency is a leading contributor to child mortality and morbidity worldwide.
Evidence & guidelines
Reference intakes for vitamins and minerals are issued by expert bodies such as the U.S. Institute of Medicine (Dietary Reference Intakes) and jointly by the World Health Organization and the Food and Agriculture Organization. These sets define average requirements, recommended intakes, and tolerable upper intake levels. The present entry summarises this framework for orientation and is not itself a clinical guideline.
History
The concept of micronutrients emerged in the early twentieth century with the isolation of the first vitamins and the recognition that diseases such as scurvy, beriberi, and rickets were deficiency diseases rather than infections. Through the twentieth century individual vitamins and essential minerals were identified, their functions characterised, and quantitative requirements established, leading to the modern framework of dietary reference values and to large-scale interventions such as salt iodisation and food fortification.
Related topics
Seminal works
- black2008
- stevens2022
- gombart2020
Frequently asked questions
- What is the difference between a micronutrient and a macronutrient?
- Macronutrients (carbohydrate, fat, and protein) are required in large amounts and supply energy, whereas micronutrients (vitamins and minerals) are required in small amounts and supply no energy, acting instead as cofactors, coenzymes, antioxidants, or structural and signalling elements.
- Why are micronutrient deficiencies called hidden hunger?
- Because a person can consume enough calories to avoid overt hunger yet still lack adequate vitamins and minerals; the resulting deficiencies impair health and development without obvious signs of starvation.