Other meanings of Nutrition
Biology and health
Nutrition is the provision of substances and energy to cells and organisms to support life, growth, repair, movement, and reproduction. It includes obtaining food, digesting it, absorbing its components, transporting them, using them in metabolism, and eliminating waste. Human nutrition depends on macronutrients, micronutrients, water, and other bioactive compounds; health reflects both the adequacy and the balance of these inputs.
Nutrition supplies the raw materials and chemical energy required for cellular life. Carbohydrates and fats are major energy sources, while proteins provide amino acids for enzymes, muscles, transport molecules, and tissue repair. Vitamins and minerals usually do not provide energy, but they regulate reactions, gene expression, fluid balance, blood formation, and skeletal development. Water is a structural and transport medium and is essential for temperature regulation. Nutrient requirements vary with age, body size, pregnancy, illness, physical activity, and environmental conditions.1
A nutrient may be essential because the body cannot synthesize enough of it, or because synthesis cannot meet physiological demand. Essential amino acids, certain fatty acids, vitamins, and minerals therefore have to be obtained from food or supplements. The nutritional value of a food also depends on bioavailability: absorption can be altered by food composition, preparation, disease, and interactions between nutrients.
Digestion converts food into molecules that can cross the intestinal lining and enter the body’s metabolic pathways. Mechanical processing and enzymes break macronutrients into absorbable units; the small intestine performs most nutrient absorption, while the liver helps process and distribute many absorbed substances. Cells then use nutrients to make adenosine triphosphate, synthesize structures, store reserves, and maintain ion gradients.
Metabolism includes catabolic reactions that release energy and anabolic reactions that build cellular components. Hormones such as insulin and glucagon coordinate nutrient use during feeding and fasting. The gut microbiome also transforms dietary compounds, especially some types of dietary fiber, producing metabolites that can affect intestinal and systemic physiology. These effects vary among individuals and are influenced by diet, medication, age, and health status.2
Healthy nutrition requires sufficient food and nutrients without excessive intake of energy, salt, free sugars, or unhealthy fats. The World Health Organization links dietary patterns rich in vegetables, fruits, legumes, nuts, whole grains, and varied protein sources with protection against several forms of chronic disease, while recommending limits on free sugars, saturated fat, trans fat, and sodium.3
Malnutrition includes undernutrition, micronutrient deficiencies, overweight, obesity, and diet-related noncommunicable disease; these conditions can coexist within the same person, household, or community. Assessment may combine dietary records, growth or body-composition measures, biochemical tests, clinical findings, and indicators of food access. Dietary reference intakes provide scientifically derived guidance for planning diets and evaluating adequacy, but they are not individualized prescriptions.4
Nutrition is shaped by food systems, culture, ecology, and access as much as by individual choice. Food insecurity can produce alternating periods of scarcity and overconsumption, while food fortification can prevent deficiencies at population scale; iodized salt, for example, has been used to reduce iodine-deficiency disorders. Processing is not uniformly harmful or beneficial: cooking can improve digestibility and destroy some pathogens, but heat or storage can reduce particular vitamins.
Some nutritional problems arise from unusual biological contexts. Malabsorption disorders, bariatric surgery, kidney disease, and certain medicines can change requirements or make ordinary diets unsafe. Nutrient–drug interactions and excessive supplementation are therefore clinically relevant. Nutrition also extends beyond humans: plants obtain mineral nutrients from soil, fungi exchange nutrients with plant roots, and animals may rely on symbiotic microbes or specialized diets. Global nutrition policy increasingly considers planetary health, food waste, agricultural diversity, and resilience alongside nutrient adequacy.15
Nutrient requirements and dietary guidance are population-based unless assessed and adapted by a qualified health professional.
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