Vitamins are essential organic compounds that catalyze metabolic reactions. They also function as electron donors, antioxidants or transcription effectors. They can be extracted from food and supplements, or in some cases, synthesized by our body or gut microbiome. Severe vitamin deficiencies result in systemic complications, including the development of scurvy, rickets, pellagra, and beriberi. Some moderate and severe deficiencies also result in oral conditions. A lower intake of vitamin A has been associated with decreased oral epithelial development, impaired tooth formation, enamel hypoplasia and periodontitis. Vitamin D deficiency during tooth development may result in non-syndromic amelogenesis and dentinogenesis imperfecta, enamel and dentin hypoplasia, and dysplasia. Clinical studies have demonstrated an association between vitamin D's endocrine effects and periodontitis. On the other hand, no significant association has been found between cariogenic activity and vitamin D deficiency. Vitamin C deficiency results in changes in the gingivae and bone, as well as xerostomia; while vitamin B deficiencies are associated with recurrent aphthous stomatitis, enamel hypomineralization, cheilosis, cheilitis, halitosis, gingivitis, glossitis, atrophy of the lingual papillae, stomatitis, rashes around the nose, dysphagia, and pallor. The effects of vitamins E and K on oral health are not as clear as those of other vitamins. However, vitamin K has a systemic effect (increasing the risk of haemorrhage), which may affect individuals undergoing oral surgery or suffering an oral injury. Health care professionals need to be aware of the effects of vitamins on oral health to provide the best available care for their patients.