Vitamins consist of four lipid-soluble vitamins (vitamins A, D, E, and K) and nine water-soluble vitamins (vitamins B1, B2, B6, B12, niacin, pantothenic acid, folic acid, biotin, and vitamin C). Lipid-soluble vitamin deficiency is caused by decreases in intake of lipid-soluble vitamins and lipid absorption. Also, if lipid-soluble vitamins are ingested or administered in excess, they are accumulated in the liver and fat and may cause hypervitaminosis. Since water-soluble vitamins are readily excreted, their storage in the body is low. Therefore, they may be deficient, and disorders due to their excess are rare. 3,4 ▋ C. Mineral Deficiency and Excess Minerals include sodium, potassium, calcium, phosphorus, and magnesium, which are classified as macro-minerals, and iron, zinc, copper, manganese, chromium, iodine, molybdenum, and selenium, which are classified as trace elements (called micro-minerals in the Dietary Reference Intakes for Japanese (2020)). The time until deficiency or excess becomes apparent varies widely among minerals. 3,5 ▋ D. Interrelations Among Nutrients In iron deficiency anemia, which is frequently observed in Japan, for example, appropriate intake of vitamin C is necessary to promote absorption of dietary non-heme iron along with increased intake of iron for symptomatic relief. Thus, approaches with sufficient consideration of interrelations among nutrients are required for the prevention and treatment of nutritional deficiency or excess.