lífefni

Lífefni are substances that living organisms require to sustain life processes, grow, repair tissues and regulate metabolism. They include a broad range of chemical compounds that must be obtained from the environment in many cases, although some can be synthesized by the organism itself. Substances that must be supplied from the diet or surroundings are termed essential lifefni, while others can be produced internally or substituted by different compounds.

Lífefni are commonly categorized into macronutrients and micronutrients. Macronutrients are needed in larger amounts and include water, carbohydrates, proteins, fats, and major minerals. Micronutrients, required in smaller amounts, comprise vitamins and trace elements. In humans, macronutrients provide energy and building blocks, while micronutrients generally act as cofactors for enzymes and as vital components of physiological processes. Carbohydrates, fats and proteins are energy-yielding, though only certain lifefni are strictly essential; many organisms also require essential amino acids or essential fatty acids they cannot synthesize.

Functions of lifefni span energy production, tissue construction, enzyme activity, hormonal signaling and maintenance of cellular balance. Vitamins often serve as enzyme cofactors, minerals participate in structural roles and electrochemical gradients, and water acts as a medium for all biochemical reactions.

Requirements vary with age, sex, health and activity level, and deficiencies can lead to specific health problems. Plants, animals and microorganisms differ in how they acquire and synthesize lifefni, reflecting diverse ecological strategies. See also nutrition and metabolism.