APA Dictionary of Psychology

a substance ingested orally to boost the nutritional content of an individual’s diet. Dietary supplements can take various forms (e.g., tablet, capsule, powder, softgel, liquid) and contain dietary ingredients such as vitamins, minerals, herbs, botanicals, amino acids, enzymes, fiber, probiotics or prebiotics, essential fatty acids, or other bioactive substances. They are typically taken for health reasons, such as to support immune functioning, increase energy, improve mental and physical performance, aid digestion, support healing, or make up for an unbalanced diet. Also called nutritional supplement.