Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D

• Published in: The Journal of nutrition Vol. 135; no. 2; pp. 317 - 322
• Main Author: Hollis, B.W
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Bethesda, MD American Society for Nutritional Sciences 01.02.2005
• Subjects: accuracy; Adult; adults; age; Biological and medical sciences; biomarkers; Biomarkers - blood; blood; bone density; Calcifediol; Calcifediol - blood; calcium; Chronic Disease; dietary recommendations; epidemiology; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; human lactation; Humans; latitude; lifestyle; literature reviews; metabolites; nationalities and ethnic groups; nutrient intake; nutrient utilization; Nutrition Policy; nutritional status; parathyroid hormone; pregnancy; prevention & control; solar radiation; Sunlight; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Vitamin D; Vitamin D Deficiency; Vitamin D Deficiency - epidemiology; Vitamin D Deficiency - prevention & control; vitamin deficiencies; vitamin metabolism; Feeding behavior; Calcium; 25-hydroxyvitamin D; vitamin D requirement; calcium absorption; Inorganic element; Recommendation; Micronutrient; Need; Absorption; Vitamin D; Food intake; Parathyroid hormone; Bone mineral density
• ISSN: 0022-3166; 1541-6100
• DOI: 10.1093/jn/135.2.317

It has been more than 3 decades since the first assay assessing circulating 25-hydroxyvitamin D [25(OH)D] in human subjects was performed and led to the definition of "normal" nutritional vitamin D status, i.e., vitamin D sufficiency. Sampling human subjects, who appear to be free from disease, and assessing "normal" circulating 25(OH)D levels based on a Gaussian distribution of these values is now considered to be a grossly inaccurate method of identifying the normal range. Several factors contribute to the inaccuracy of this approach, including race, lifestyle habits, sunscreen usage, age, latitude, and inappropriately low dietary intake recommendations for vitamin D. The current adult recommendations for vitamin D, 200-600 IU/d, are very inadequate when one considers that a 10-15 min whole-body exposure to peak summer sun will generate and release up to 20,000 IU vitamin D-3 into the circulation. We are now able to better identify sufficient circulating 25(OH)D levels through the use of specific biomarkers that appropriately increase or decrease with changes in 25(OH)D levels; these include intact parathyroid hormone, calcium absorption, and bone mineral density. Using these functional indicators, several studies have more accurately defined vitamin D deficiency as circulating levels of 25(OH)D </= 80 nmol or 32 [micro]g/L. Recent studies reveal that current dietary recommendations for adults are not sufficient to maintain circulating 25(OH)D levels at or above this level, especially in pregnancy and lactation.