Many of the children that a pediatric gastroenterologist sees are at risk for Vitamin D deficiency, including children with inflammatory bowel disease, cystic fibrosis, celiac disease, and liver diseases. In addition, vitamin D deficiency is widespread: in U.S. 50% of children aged 1-5 years and 70% 6-11 years are vitamin D deficient or insufficient. A thorough review on this “D-lightful” vitamin was in a recent JPEN (JPEN J Parenter Enteral Nutr 2012; 9S-19S).
History: In 1822 Sniadecki recognized children in urban but not rural Poland developed rickets. He postulated the effects of the sun as the reason for rickets; his idea was dismissed. In 1920s, the concept of irradiating milk to prevent rickets emerged. In 1950s, outbreak of hypercalcemia in infants in Great Britain was thought to be related to vitamin D fortification and curtailed this practice in Europe. However, these cases were likely due to Williams syndrome.
Sources of vitamin D: oily fish (salmon), cod liver oil, some mushrooms, egg yolk, & sunlight. Exposure of an adult in a bathing suit to one minimal erythemal dose (MED) is equivalent to ingesting 20,000 IUs of Vitamin D. (The minimal dose that induces any visible reddening at that point is defined as one MED.)
Effect of sunscreen: A sun protection factor (SPF) of 30 absorbs approximately 98% of solar ultaviolet radiation & thus lowers vitamin D production by 98%.
Ethnicity: Melanin is an effective SPF. A person of african-american descent, on average, has an SPF of 15, which reduces vitamin D production by 90%.
Age: Aging decreases 7-dehydrocholesterol in human skin. Due to this, the elderly produce much less vitamin D. For example, a 70 year old has a 75% reduction compared to a 20 year old.
Forms of vitamin D: 25-hydroxyvitamin D (25OH-D) is the major circulating form of vitamin D & physicians measure 25OH-D. 25OH-D is metabolized in kidney to 1,25-dihydroxyvitamin D (1,25OH-D), also called calcitriol. This is the most biologically-active and is responsible for increasing intestinal calcium absorption and mobilizing calcium from bone. However, 1,25OH-D provides no information vitamin D deficiency; it can be elevated or normal in deficiency states.
- Cholecalciferol (vitamin D-3) is formed in the skin from 5-dihydrotachysterol.
- Ergocalciferol (Vitamin D-2) is the form in Drisdol (8000 IU/mL) & Ergocalciferol Capsules (1.25 mg =50,000 USP Units)
Vitamin D deficiency: The exact numbers are debated. The institute of medicine (IOM) has considered individuals deficient if 25OH-D is <20 ng/mL. The Endocrine Society and the author suggest vitamin D deficiency as <20 ng/mL & insufficiency as <30 ng/mL. The author recommends ideal levels between 40-60 ng/mL.
Consequences of deficiency:
Osteoporosis, Osteopenia, Rickets (see references below): Bone weakening occurs due to loss of phosphorus from the kidneys. Vitamin D deficiency lowers accrual of calcium in skeleton and leads to osteoporosis, osteopenia, and rickets. Imaging for rickets: the best single radiographic view for infants and children younger than 3 years is an anterior view of the knee that reveals the metaphyseal end and epiphysis of the femur and tibia. This site is best because growth is most rapid in this location, thus the changes are accentuated.
Nonskeletal consequences: vitamin D deficiency is associated with increased risk for preeclampsia, URIs, asthma, diabetes (type 1), multiple sclerosis, hypertension, and schizophrenia.
- Infants who are breastfed should be receiving supplemental vitamin D, 400 IU/day.
- Adults/children (>1 year) RDA 600 IU/day –mostly from diet per IOM. Yet author states, “it is unrealistic to believe that diet alone can ….provide this requirement.”
- In vitamin D deficient patients: (initial treatment) 2000 IU/day or 50,000 IU/week for 6 weeks.
Toxicity from vitamin D (from NEJM 2010; 364: 248-254.): “Toxicity from vitamin D supplementation is rare and consists principally of acute hypercalcemia, which usually results from doses that exceed 10,000 IU per day; associated serum levels of 25-hydroxyvitamin D are well above 150 ng per milliliter (375 nmol per liter). The tolerable upper level of daily vitamin D intake recently set by the Institute of Medicine (IOM) is 4000 IU.”
- -Pediatrics 2008; 122: 398. Should give 400 IU/day to breastfed babies. Consequences of Vit D deficiency: increased risk for DM, multiple sclerosis, cancer (breast, prostate,colon), rickets, and schizophrenia. Article lists vit D content of foods (high in cod liver oil, shrimp, fortified milk, many fish). Severe deficiency when < 5ng/mL, deficient if < 15 ng/mL; probably should be >32 ng/mL. Causes of vit D deficiency: decreased synthesis (due to lack of sun -skin pigmentation, sunscreen/clothing, geography, clouds), decreased intake, decreased maternal stores & breastfeeding, malabsorption (eg celiac, CF, EHBA, cholestasis), increased degradation; treatment of rickets: double-dose of vitamin d (~1000 IU/day for babies & 5000 for older kids) x 3-4 months along with calcium (30-75/mg/kg/day). Follow Ca/phos/alk phos monthly. Alternatively, give ~100,000 units over 1-5 days.
- -JPEN J Parenter Enteral Nutr. 2011;35:308-316-Results: The study included 504 IBD patients (403 Crohn’s disease [CD] and 101 ulcerative colitis [UC]) who had a mean disease duration of 15.5 years in CD patients and 10.9 years in UC patients; 49.8% were vitamin D deficient, with 10.9% having severe deficiency. Vitamin D deficiency was associated with lower HRQOL (regression coefficient –2.21, 95% confidence interval [CI], –4.10 to –0.33) in CD but not UC (regression coefficient 0.41, 95% CI, –2.91 to 3.73). Vitamin D deficiency was also associated with increased disease activity in CD (regression coefficient 1.07, 95% CI, 0.43 to 1.71). Conclusions: Vitamin D deficiency is common in IBD and is independently associated with lower HRQOL and greater disease activity in CD. There is a need for prospective studies to assess this correlation and examine the impact of vitamin D supplementation on disease course.
- -JPGN 2011;53: 361. similar prevalence of low Vitamin D as general population –58% with less than 32.
- -JPGN 2011; 53: 11. Guidelines for bone disease with inflammatory bowel disease.
- -Pediatrics 2010; 125: 633. Increasing Vit D deficiency noted in minority children. n=290. 22% w levels <20, 74% <30.
- -Hepatology 2011; 53: 1118. Good vitamin D levels are another favorable predictive factor in antiviral response to Hep C along with IL28B.
- -NEJM 2010; 364: 248-254. Vitamin D insufficiency. Levels between 20-30 may be OK -not enough evidence to determine conclusively whether this level is detrimental
- -J Pediatr 2010; 156: 948. High rate among african americans with asthma, 86%. n=63.
- -Pediatrics 2009; 124:e362. n=6275. 9% of pediatric patients vit D deficient & 61% were insufficient.
- -Pediatrics 2009; 124:e371. n=3577. low 25OH-D levels inversely assoc with SBP/metabolic syndrome.
- -NEJM 2009; 360: 398. case report of rickets
- -J Pediatr 2003; 143: 422 & 434
- -Pediatrics 2003; 111: 908. 200 IU Vit D recommended for all breastfed infants.
- -J Pediatr 2000;137: 153 & 143.. Nutritional rickets–primarily in blacks; rec vitamin D 400 IU per day.