Trends in Supplemental Vitamin D Intake

• Published in: Integrative medicine alert 2019-01, Vol.22 (1)
• Main Author: Pantuso, Traci
• Format: Article
• Language: English
• Subjects: Age; Dietary supplements; Gastrointestinal surgery; Hispanic people; Nutrition research; Pandemics; Pediatrics; Skin; Trends; Vitamin D; Vitamin deficiency; Womens health
• ISSN: 2325-2812; 2325-2820

Vitamin D is a fat-soluble vitamin that either is consumed through dietary sources or synthesized when skin is exposed to ultraviolet light.1 The benefits of adequate vitamin D intake are well demonstrated in the skeletal system, as severe vitamin D deficiency results in rickets in children and osteomalacia in adults.1,2 The role of vitamin D in extraskeletal health is not well understood, and the majority of evidence to support its use is from association and observational studies.1,3,4 Some consider hypovitaminosis D, which is caused by low levels of vitamin D naturally occurring in foods and a lack of sufficient sunlight exposure, to be a pandemic worldwide.5 Individuals with increased melanin in their skin and those who use sunblock have decreased vitamin D synthesis resulting from sunlight exposure.4,5 Because of inadequate dietary intake of vitamin D and decreased synthesis from sunlight exposure, many individuals require oral vitamin D supplementation.1-8 To assess the changes in vitamin D intake from 1999 to 2014 and investigate trends of use, Rooney et al used repeat cross-sectional data from the National Health and Nutrition Examination Survey (NHANES), which samples U.S. residents who are not institutionalized. According to Labdoor, a company that tests supplements, an analysis of 19 of the best-selling vitamin D supplements in the United States found that all of the products exceeded their vitamin D label claims by 22%, and six products exceeded their label claims by 40%.11 Multivitamins usually contain label claims of 400 IU/day. Gailor et al reviewed case reports of vitamin D toxicity, which included information about how much vitamin D was being taken, the serum vitamin D level at the time of admission, and a complete medical evaluation.10 They found that most cases of vitamin D toxicity are due to intake of vitamin D supplements that exceed their label claims.10 The authors found that serum levels > 150 ng/mL posed toxicity risks and should be avoided.10 Vitamin D intoxication leads to hypercalcemia through increased calcium absorption in the gut and hypercalciuria. Certain populations are at risk of vitamin D deficiency, including breastfed infants, people with limited sun exposure, people with dark skin, older adults, people with decreased fat absorption, individuals with inflammatory bowel disease, people with obesity, and those who have undergone gastric bypass surgery.1,2,3,6,8 Although serum 25(OH)D levels are the best indicator of vi