Vitamin D

1. Advantages
1. "Low vitamin D levels are associated with depressive symptoms."
2. In this study of obese, adolescent females, low blood levelsof vitamin D were associated with higher glucose (sugar) but lower LDL (bad)cholesterol levels. Treating those with vitamin D deficiency resulted in lowerglucose levels. 
3. VitaminD deficiency is associated with susceptibility to active tuberculosis.  (11/28/11)
4. Decreased Risk of Diabetes (9/3/12)
1. "The incidence of diabetes in subjects with 25-hydroxyvitamin D levels ≤18.5 ng/mL (percentile 25) was 12.4% vs 4.7% in subjects with levels >18.5 ng/mL." (Clinical NutritionVolume 31, Issue 4 , Pages 571-573, August 2012. 9/3/12)
5. Colds (8/21/12)
1. In this study, 4000IU of vitamin D3 or a placebo was given daily for 1year. The group that received the vitamin D had less cold symptoms. (BMJ Open 2012;2:e001663 doi:10.1136/bmjopen-2012-001663, 12/14/12)
2. "In this trial, monthly administration of 100 000 IU of vitamin D did not reduce the incidence or severity of URTIs [Upper Respiratory Tract Infections] in healthy adults." (JAMA. 2012;308(13):1333-1339. doi:10.1001/jama.2012.12505, 10/3/12)
3. "Compared with controls, children receiving vitamin D reported significantly fewer ARIs during the study period (mean: 0.80 vs 0.45; P = .047), with a rate ratio of 0.52 (95% confidence interval: 0.31–0.89)." ( doi: 10.1542/peds.2011-3029, 8/21/12)
6. Decrease asthma exacerbation (7/20/12)
1. "Vitamin D insufficiency is associated with severe asthma exacerbations in Puerto Rican children, independently of racial ancestry, atopy, or markers of disease severity or control." ( Am. J. Respir. Crit. Care Med.July 15, 2012 vol. 186 no. 2 140-146, 7/20/12)
7. Decease fracture risk (7/8/12)
1. "High-dose vitamin D supplementation (≥800 IU daily) was somewhat favorable in the prevention of hip fracture and any nonvertebral fracture in persons 65 years of age or older." ( N Engl J Med 2012; 367:40-49, 7/8/12)
8. Decreased  colorectal  cancer risk (3/5'5/12)
1. "Observational studies have been largely consistent in showing an inverse association between vitamin D and an individual’s risk of developing colorectal cancer." ( Carcinogenesis (2012) 33 (3):475-482. 3/5/12)
2. Mechanism of Action
1. In conclusion, this study identified the upregulation of MKP-1 by vitamin D as a novel pathway by which vitamin D inhibits LPS-induced p38 activation and cytokine production in monocytes/macrophages.( The Journal of Immunology March 1, 2012 vol. 188 no. 5 2127-2135, 2/23/12)
3. Levels vary with season
1. The mean vitamin D level ranged from 32.9 ng/mL in January to 55.4 ng/mL in September. (SMJ, 2/6/12)
4. Risk factors for  Insufficient levels of vitamin D
1. Younger age (younger than 40 years)  (SMJ, 2/6/12) 
2. No milk or fish consumption (SMJ, 2/6/12) 
3. No use of multivitamins, vitamin D supplements, or calcium supplements (SMJ, 2/6/12) 
4. No sun exposure (SMJ, 2/6/12) 
5. Routine use of sunscreens (SMJ, 2/6/12)