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REVIEW ARTICLE |
1 From the Department of Nutrition, Harvard School of Public Health, Boston, MA (HAB-F, EG, and WCW); the Department of Rheumatology and the Institute of Physical Medicine, University Hospital Zurich, Zurich, Switzerland (HAB-F); the Department of Epidemiology and the Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA (EG and WCW); the Department of Health Policy and Health Services Research, Boston University Goldman School of Dental Medicine, Boston, MA (TD); and the Jean Mayer USDA Human Nutrition Research Center on Aging, Tufts University, Boston, MA (BD-H)
2 Supported by the Medical Foundation (Charles A King Trust, Fleet National Bank, Co-Trustee, Boston, MA), the Harvard Hartford Foundation, the Kirkland Scholar Award, Irene and Fredrick Stare Nutrition Education Fund, the International Foundation for the Promotion of Nutrition Research Education, and the Swiss Foundation for Nutrition Research. 3 Reprints not available. Address correspondence to HA Bischoff-Ferrari, Department of Rheumatology, Institute of Physical Medicine, University Hospital Zurich, Gloriastrasse 25, 8091 Zurich, Switzerland. E-mail: heike.bischoff{at}usz.ch.
| ABSTRACT |
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1000 IU (40 µg) vitamin D (cholecalciferol)/d is needed to bring vitamin D concentrations in no less than 50% of the population up to 75 nmol/L. The implications of higher doses for the entire adult population should be addressed in future studies.
Key Words: 25-Hydroxyvitamin D vitamin D intake bone density lower-extremity strength colorectal cancer
| INTRODUCTION |
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This review draws together recent work by the authors and places it in the context of other research to estimate the optimal 25(OH)D concentration for multiple health outcomes. Specifically, we examine several alternative endpoints to the maximal suppression of PTH or optimal calcium absorption, including bone mineral density (BMD) in younger and older adults of different racial or ethnic backgrounds and antifracture efficacy, as ascertained in a recent meta-analysis of double-blind randomized controlled trials (RCTs; 13). We also evaluated optimal 25(OH)D concentrations for nonskeletal outcomes of public health significance, including lower-extremity function, falls, dental health, and colorectal cancer prevention. Finally, our goal was to ascertain the optimal 25(OH)D concentrations and the corresponding vitamin D intakes throughout adult life that best enhance health (14).
| MATERIALS AND METHODS |
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We reviewed studies that evaluated threshold concentrations for 25(OH)D regarding the above outcomes. The most recent studies designed by some of the authors of this review to define such thresholds are shown as figures and are the focus of this review and data synthesis (28-31).
Concentrations of 25-hydroxyvitamin D and bone health
Background
In a large part of the population, including younger persons and nonwhite racial-ethnic groups, BMD may be a better endpoint than serum PTH for the estimation of optimal 25(OH)D concentrations with respect to bone health. In the elderly, BMD is a strong predictor of fracture risk (32), and evidence from several RCTs suggests a positive effect of vitamin D supplementation on BMD (33-35). Moreover, BMD integrates the lifetime effect of many influences on the skeleton, including PTH.
Optimal 25-hydroxyvitamin D concentrations for BMD
A threshold for optimal 25(OH)D and BMD has been addressed only recently (28). The association between serum 25(OH)D and hip BMD among 13 432 subjects of the third National Health and Nutrition Examination Survey (NHANES III), including both younger (2049 y) and older (
50 y) persons with different ethnic-racial backgrounds was examined by some of the authors of this review (28). Compared with subjects in the lowest quintile of 25(OH)D, those in the highest quintile had mean BMD that was 4.1% higher in younger whites (P for trend < 0.0001), 4.8% higher in older whites (P < 0.0001), 1.8% higher in younger Mexican Americans (P = 0.004), 3.6% higher in older Mexican Americans (P = 0.01), 1.2% higher in younger blacks (P = 0.08), and 2.5% higher in older blacks (P = 0.03). In the regression plots, higher serum 25(OH)D concentrations were associated with higher BMD throughout the reference range of 22.5 to 94 nmol/L in all subgroups (Figure 1
). In younger whites and younger Mexican Americans, higher 25(OH)D was associated with higher BMD, even that >100 nmol/L.
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Greater antifracture efficacy with higher achieved 25(OH)D concentrations in the treatment group for both hip and any nonvertebral fracture, a difference that reached significance in metaregression analyses, is shown in Figure 2
). It appears that optimal fracture prevention occurred in trials with mean achieved 25(OH)D concentrations of
100 nmol/L. These concentrations were reached only in trials that gave 700800 IU cholecalciferol/d to subjects with mean baseline concentrations between 44 and 77 nmol/L. Thus, optimal fracture prevention may require intakes of >700800 IU vitamin D/d in populations with baseline 25(OH)D concentrations <44 nmol/L, and baseline concentrations may depend on latitude (44), type of dwelling (45, 46), and fortification of dairy products with vitamin D (47). Low baseline concentrations may in part explain why 2 recent trials from the United Kingdom (UK), which were not included in our meta-analysis, did not achieve antifracture efficacy with 800 IU cholecalciferol/d (48, 49). The UK has little sunshine, and food is not commonly fortified with vitamin D. In the Randomized Evaluation of Calcium or Vitamin D (RECORD Trial; 48), starting from a mean concentration of 15.2 ng/mL (38 nmol/L), the achieved mean 25(OH)D concentrations were only 62 nmol/L in the vitamin D treatment group. This is, according to our meta-analysis, not enough for fracture prevention (Figure 2B
). Moreover, the increase in mean 25(OH)D concentrations by 24 nmol/L is small for an intake of 800 IU/d and was observed with an intake of 400 IU vitamin D/d in another European population (50). This suggests that participants in the RECORD Trial were not sufficiently compliant. In fact, the documented compliance rate was 60% at 12 mo and 47% at 24 mo in persons who returned the 4-mo questionnaire, and even lower if all participants were considered. In addition, the RECORD Trial was a secondary prevention trial, whereas the meta-analysis (Figure 2
) included only primary prevention trials. In the second UK trial, by Porthouse et al (49), 25(OH)D concentrations were not reported. Furthermore, the open design and instruction of the control group to ensure adequate calcium and vitamin D intakes may have biased the result toward the null. Still, those authors reported an effect size for hip fracture prevention with vitamin D that is similar to the result of the meta-analysis (RR = 0.75; 95% CI: 0.31, 1.78), although surrounded by a large CI. Thus, the data for bone health, based on BMD in younger and older adults and on the prevention of hip and any nonvertebral fractures in older adults, suggest that serum 25(OH)D concentrations between 90 and 100 nmol/L are desirable.
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Some of the authors of this review addressed the effect of vitamin D on the risk of falling in older persons in a recent meta-analysis (61). Combined evidence from 5 RCTs (n = 1237) showed that vitamin D reduced the risk of falling by 22% (pooled corrected OR = 0.78; 95% CI: 0.64, 0.92) compared with calcium or placebo (37, 50, 57, 62, 63). Subgroup analyses suggested that the reduction in risk was independent of the type of vitamin D, duration of therapy, and subject's sex. However, the results from one trial suggested that 400 IU vitamin D/d may not be clinically effective in preventing falls in the elderly (50), whereas 2 trials that used 800 IU vitamin D/d plus calcium showed a lower risk of falling (37, 57). For the 2 trials with 259 subjects using 800 IU cholecalciferol/d, the corrected pooled OR was 0.65 (95% CI: 0.40, 1.00; 61). A recent double-blind RCT comparing the long-term effect of 700 IU vitamin D plus 500 mg calcium with placebo confirmed a beneficial effect on falls in 246 community-dwelling older women: the odds of falling declined by 46% [odds ratio (OR): 0.54; 95% CI: 0.30, 0.97; 64). Fall reduction was most pronounced in less active women (OR: 0.35; 95% CI: 0.15, 0.81), whereas the effect in community-dwelling older men (n = 199) was neutral (OR: 0.93; 95% CI: 0.50, 1.72).
A physiologic explanation for the beneficial effect of vitamin D on muscle strength is that 1,25-dihydroxyvitamin D (1,25(OH)2D), the active vitamin D metabolite, binds to a vitamin Dspecific nuclear receptor in muscle tissue (65-67), which leads to de novo protein synthesis (54, 58), muscle cell growth (58), and improved muscle function (29, 37, 55, 57). Higher serum 25(OH)D concentrations increase the substrate concentration for intracellular, tissue-specific 1-
-hydroxylases, thereby permitting intracellular concentrations of 1,25(OH)2D to rise in muscle and other tissues (68).
Optimal 25-hydroxyvitamin D concentrations and lower-extremity function
A threshold for optimal 25(OH)D and lower-extremity function has only recently been addressed (29). Some of the authors of this review examined the association between serum 25(OH)D concentrations and lower-extremity function in 4100 ambulatory older adults in NHANES III (29). Functional assessments included the 8-foot-walk test and the sit-to-stand test (69, 70). Both tests depend on lower-extremity strength, and they mirror functions needed in everyday life.
The association between 25(OH)D concentrations and lower-extremity function is shown in Figure 3
. In both tests, performance speed continued to increase throughout the reference range of 25(OH)D (ie, 22.594 nmol/L); most of the improvement occurred at 25(OH)D concentrations from 22.5 to
40 nmol/L. Further improvement was seen at concentrations in the range of 40 to 94 nmol, but the magnitude was less dramatic. Results of the 8-foot-walk test in the subjects in the highest quintile of 25(OH)D were 5.6% lower than the results in subjects in the lowest quintile of 25(OH)D (P for trend < 0.001). Results of the sit-to-stand test in the subjects in the highest quintile of 25(OH)D were 3.9% lower than the results in the subjects in the lowest quintile of 25(OH)D (P for trend = 0.017).
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500 mg/d) calcium intakes. Only for the sit-to-stand test did there appear to be a decline in performance speed at the highest 25(OH)D concentrations (>120 nmol/L), but this was based on a relatively small number of observations.
Thus, the data for lower-extremity strength suggest that serum 25(OH)D concentrations of
40 nmol/L are desirable, but those of 90 to 100 nmol/L are best. This finding is supported by data from the Longitudinal Aging Study Amsterdam that included 1351 Dutch men and women aged
65 y (71). In that study, a physical performance score (chair stands, a walking test, and a tandem stand) showed the greatest improvement from very low concentrations of serum 25(OH)D up to 50 nmol/L and had less pronounced but continuous improvement at concentrations >50 nmol/L (65).
25-Hydroxyvitamin D and periodontal disease
Background
Periodontal disease is a common chronic inflammatory disease in middle-aged and older persons that is characterized by the loss of periodontal attachment, including the periodontal ligaments and alveolar bone. Periodontal disease is the leading cause of tooth loss, particularly in older persons (72-75), and tooth loss is an important determinant of nutrient intakes and quality of life (76-78). Several epidemiologic studies have reported positive associations between osteoporosis or low bone density and alveolar bone and tooth loss, which indicate that poor bone quality may be a risk factor for periodontal disease (79-85). In one RCT, supplementation with vitamin D (700 IU/d) plus calcium (500 mg/d) significantly reduced tooth loss in older persons over a 3-y treatment period (OR: 0.4; 95% CI: 0.2, 0.9), whereas serum 25(OH)D concentrations increased from 71 to 112 nmol/L (86). Vitamin D may also reduce periodontal disease through its anti-inflammatory effect (87, 88).
Optimal 25-hydroxyvitamin D concentrations and periodontal disease
Apart from the above-mentioned RCT that successfully tested vitamin D plus calcium in relation to the prevention of tooth loss in ambulatory elderly men and women (86), little direct evidence that vitamin D status is an important determinant of periodontal disease has appeared in the literature. Some of the authors of this review therefore evaluated the association between 25(OH)D concentrations and alveolar attachment loss, a measure of periodontal disease, in 11 202 ambulatory subjects aged
20 y in NHANES III (30). That analysis found that 25(OH)D status was not significantly associated with attachment loss in younger men and women (aged 2050 y), but, in persons aged > 50 y, a significant association between 25(OH)D and attachment loss was observed in both sexes, independent of race-ethnicity (P for trend = 0.001 in men and 0.008 in women). The quintiles of 25(OH)D concentrations in relation to the degree of attachment loss are shown in Figure 4
. The BMD of the total hip region was not associated with attachment loss, and adjustment for that did not attenuate the association between 25(OH)D and attachment loss, which suggests that vitamin D, independent of bone, may play a role in attachment loss. Thus, although data vitamin D and dental health outcomes are limited, available evidence suggests that serum 25(OH)D concentrations between 90 and100 nmol/L are desirable.
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Optimal 25-hydroxyvitamin D concentrations for colorectal cancer prevention
Until recently, studies of 25(OH)D concentrations and colorectal cancer risk have been too small to identify a threshold for 25(OH)D. In the first small US study, involving 34 cases, persons with concentrations >50 nmol/L had an RR of 0.3 (which was statistically significant) relative to those with lower concentrations (91). In a study of 146 cases conducted in Finland that compared the lowest (<24.5 nmol/L) with the highest (>48.3 nmol/L) quintile, the RR was 0.6 (95% CI: 0.3, 1.1; 92). In the recent analysis in the Nurses' Health Study involving 193 incident cases, serum 25(OH)D concentrations were inversely related to colorectal cancer risk (31). As shown in Figure 5
, the RR decreased monotonically across quintiles of 25(OH)D concentrations; the RR was 0.53 (95% CI: 0.27, 1.04) for quintile 5 (median: 88 nmol/L) as compared with quintile 1 (median: 38 nmol/L; P for trend = 0.02).
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Some studies have examined vitamin D intakes in relation to risk of colorectal cancer. In those that have taken into account supplementary vitamin D, an inverse association has invariably been observed (100-102, 105, 112-114). In these studies, the cutoff for the top category was 500600 IU/d, with an average of
700800 IU/d in this category. The risk reduction in the top category compared with the bottom category was as follows: 46% (101), 34% (100), 58% (102), 24% (114), 30% (112), 29% in males and 0% in females (105), and 50% in males and 40% in females (113).
Findings from the WHI appear to contrast with the epidemiologic data described in this review (121). However, 2 critical issues are dose and duration of supplementation. In the Nurses' Health Study, a significant reduction in colorectal cancer in connection with higher vitamin D intake emerged only at doses >550 IU/d in consistent users for >10 y (RR = 0.42; 95% CI: 0.19, 0.91; 96). In the WHI, median follow-up was only 7 y. Furthermore, similar to the most recent findings on 25(OH)D concentrations and risk of colorectal cancer in the Nurses' Health Study (Figure 5
; 31), a significant (P = 0.02) inverse trend between lower baseline serum 25(OH)D concentrations and a greater risk of colorectal cancer was observed in the WHI participants.
Thus, epidemiologic data for colorectal neoplasia, based on cancer and adenomas, are generally consistent with a protective effect of a higher 25(OH)D concentration and higher vitamin D intake. It has been suggested that there may be a local effect on colonic epithelial cells with increasing 25(OH)D concentrations leading to less cell proliferation and greater cell differentiation (122). Estimated optimal serum 25(OH)D concentrations were
90 nmol/L. This conclusion is supported by a 2004 National Institutes of Healthsponsored symposium at which the role of vitamin D in cancer chemoprevention and treatment was discussed (123-125).
Vitamin D intake needed to achieve optimal 25-hydroxyvitamin D concentrations
Currently recommended intakes of vitamin D are 200 IU/d for young adults, 400 IU/d for those aged 5170 y, and 600 IU/d for those aged >70 y (126). The vitamin D intake needed to bring the concentrations in a large majority of adults to the desirable 90100 nmol/L 25(OH)D range has not been defined precisely and depends to some extent on the starting intake. Studies in older persons show that 25(OH)D concentrations could be increased by
1040 nmol/L to means of
60 nmol/L with an intake of 400 IU vitamin D/d (43, 127, 128), by 31 nmol/L to means of 79 nmol/L with 600 IU (129), or by 5065 nmol/L to means of 100 nmol/L with 800 IU vitamin D/d (33, 34). Mean concentrations of 75 to 100 nmol/L are achieved with intakes of 700 to 1000 IU/d in groups of young and older adults (130-132). In young men and women (aged 41 ± 9 y), 4000 IU vitamin D/d (100 µg/d) may increase 25(OH)D concentrations by 56 nmol/L to means of 125 nmol/L (133).
| DISCUSSION |
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75 nmol 25(OH)D/L for optimal health is supported by several experts and a recent conference on the role of vitamin D in cancer prevention (124, 125, 134-138).
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According to a recent national survey in the United States, only 31% of whites aged 2049 y, <9% of older whites, and an even smaller fraction of Mexican American and African American adults have serum 25(OH)D concentrations of
90 nmol/L (28). Most vulnerable to low vitamin D concentrations are the elderly (45, 142), persons living in northern latitudes where the winters are prolonged (9, 143), obese persons (144), and African Americans of all ages (28, 145, 146). Other groups with dark skin pigmentation living in northern latitudes will also be at high risk of low vitamin D status. Thus, a large majority of the US population could benefit from vitamin D supplementation, which is a simple, highly affordable, and well-tolerated strategy that could reduce osteoporosis and fractures and could probably reduce falls associated with lower-extremity weakness, could improve dental health, and reduce the incidence of colorectal cancer in older adults.
Our review also estimated the vitamin D intakes that may be required to achieve the optimal concentration of 25(OH)D. Studies suggest that 7001000 IU vitamin D/d may bring 50% of younger and older adults up to a concentration of 90100 nmol/L (130-132). Thus, to bring most adults to the desirable range of 90100 nmol/L, vitamin D doses higher than 7001000 IU would be needed. The current intake recommendation for older persons (600 IU/d) may bring concentrations in most subjects to 5060 nmol/L, but not to 90100 nmol/L, and, for younger adults, the current recommendation of 200 IU/d (5 µg/d) is unlikely to be adequate (28). According to studies in younger adults, intakes as high as 400010 000 IU/d (250 µg/d) are safe (127, 133), and those of 4000 IU may bring concentrations in 88% of healthy young men and women to
75 nmol/L (133). Heaney (124) and Heaney et al (127), in a study of healthy men, estimated that 1000 IU cholecalciferol/d is needed during the winter months in Nebraska to maintain the concentration of 70 nmol/L that subjects had in late summer, whereas persons with baseline concentrations between 20 and 40 nmol/L may require a daily dose of 2200 IU vitamin D to reach and maintain concentrations of 80 nmol/L (124, 127).
If 75100 nmol/L were the target range of a revised recommended daily allowance (RDA), the new RDA should meet the requirements of 97% of the population (147). The dose-response calculations of
1.0 nmol/L (l µg/d) at the lowest end of the distribution and of 0.6 nmol/L (l µg/d) at the highest end, proposed by Heaney (124), suggest that a daily oral dose of 2000 IU (50 µg/d), the safe upper intake limit as defined by the National Academy of Science (126), may shift the NHANES III distribution so that only
1015% of persons had concentrations < 75 nmol/L. This calculation may result in a shift of 35 nmol/L in already-replete persons from concentrations between 75 and 140 nmol/L (NHANES III distribution) to concentrations of 110175 nmol/L, which are observed in healthy outdoor workers [ie, farmers: 135 nmol/L (148) and lifeguards: 163 nmol/L (149)]. Thus, 2000 IU may be a safe RDA even at the higher end of the normal 25(OH)D serum concentration distribution, and, at the lower end, it may be conservative. As a first sign of toxicity, only serum 25(OH)D concentrations of >220 nmol/L have been associated with hypercalcemia (150, 151).
Because of seasonal fluctuations in 25(OH)D concentrations (9), some persons may be in the target range during the summer months. However, these concentrations will not be sustained during the winter months, even in sunny latitudes (129, 137). Thus, even after a sunny summer, winter supplementation with vitamin D is needed. Furthermore, several studies suggest that many older persons will not achieve optimal serum 25(OH)D concentrations during the summer months, which suggests that vitamin D supplementation should be independent of season in older persons (142, 152, 153).
On the basis of this review, we suggest that, for bone health in younger adults and all outcomes in older adults, including antifracture efficacy, lower-extremity strength, dental health, and colorectal cancer prevention, an increase in the current recommended intake of vitamin D may be warranted. To bring concentrations in
50% of the population up to 75 nmol vitamin D/L, we recommend that intakes for adults should be
1000 IU vitamin D/d in all racial-ethnic groups. Given the low cost, the safety, and the demonstrated benefit of higher 25(OH)D concentrations, vitamin D supplementation should become a public health priority to combat these common and costly chronic diseases.
| ACKNOWLEDGMENTS |
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S. M Smith, K. K Gardner, J. Locke, and S. R Zwart Vitamin D supplementation during Antarctic winter Am. J. Clinical Nutrition, April 1, 2009; 89(4): 1092 - 1098. [Abstract] [Full Text] [PDF] |
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V. Mocanu, P. A Stitt, A. R. Costan, O. Voroniuc, E. Zbranca, V. Luca, and R. Vieth Long-term effects of giving nursing home residents bread fortified with 125 {micro}g (5000 IU) vitamin D3 per daily serving Am. J. Clinical Nutrition, April 1, 2009; 89(4): 1132 - 1137. [Abstract] [Full Text] [PDF] |
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A. A. Ginde, M. C. Liu, and C. A. Camargo Jr Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988-2004 Arch Intern Med, March 23, 2009; 169(6): 626 - 632. [Abstract] [Full Text] [PDF] |
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A. Merewood, S. D. Mehta, T. C. Chen, H. Bauchner, and M. F. Holick Association between Vitamin D Deficiency and Primary Cesarean Section J. Clin. Endocrinol. Metab., March 1, 2009; 94(3): 940 - 945. [Abstract] [Full Text] [PDF] |
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E. A Yetley, D. Brule, M. C Cheney, C. D Davis, K. A Esslinger, P. W. Fischer, K. E Friedl, L. S Greene-Finestone, P. M Guenther, D. M Klurfeld, et al. Dietary Reference Intakes for vitamin D: justification for a review of the 1997 values Am. J. Clinical Nutrition, March 1, 2009; 89(3): 719 - 727. [Abstract] [Full Text] [PDF] |
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A. A. Ginde, J. M. Mansbach, and C. A. Camargo Jr Association Between Serum 25-Hydroxyvitamin D Level and Upper Respiratory Tract Infection in the Third National Health and Nutrition Examination Survey Arch Intern Med, February 23, 2009; 169(4): 384 - 390. [Abstract] [Full Text] [PDF] |
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R. Eastell, A. Arnold, M. L. Brandi, E. M. Brown, P. D'Amour, D. A. Hanley, D. S. Rao, M. R. Rubin, D. Goltzman, S. J. Silverberg, et al. Diagnosis of Asymptomatic Primary Hyperparathyroidism: Proceedings of the Third International Workshop J. Clin. Endocrinol. Metab., February 1, 2009; 94(2): 340 - 350. [Abstract] [Full Text] [PDF] |
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E. Giovannucci Expanding Roles of Vitamin D J. Clin. Endocrinol. Metab., February 1, 2009; 94(2): 418 - 420. [Full Text] [PDF] |
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R. Kremer, P. P. Campbell, T. Reinhardt, and V. Gilsanz Vitamin D Status and Its Relationship to Body Fat, Final Height, and Peak Bone Mass in Young Women J. Clin. Endocrinol. Metab., January 1, 2009; 94(1): 67 - 73. [Abstract] [Full Text] [PDF] |
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S. M. Arpadi, D. McMahon, E. J. Abrams, M. Bamji, M. Purswani, E. S. Engelson, M. Horlick, and E. Shane Effect of Bimonthly Supplementation With Oral Cholecalciferol on Serum 25-Hydroxyvitamin D Concentrations in HIV-Infected Children and Adolescents Pediatrics, January 1, 2009; 123(1): e121 - e126. [Abstract] [Full Text] [PDF] |
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J. H. Lee, J. H. O'Keefe, D. Bell, D. D. Hensrud, and M. F. Holick Vitamin D Deficiency: An Important, Common, and Easily Treatable Cardiovascular Risk Factor? J. Am. Coll. Cardiol., December 9, 2008; 52(24): 1949 - 1956. [Abstract] [Full Text] [PDF] |
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M Sneve, Y Figenschau, and R Jorde Supplementation with cholecalciferol does not result in weight reduction in overweight and obese subjects Eur. J. Endocrinol., December 1, 2008; 159(6): 675 - 684. [Abstract] [Full Text] [PDF] |
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S. O'Donnell, A. Cranney, T. Horsley, H. A Weiler, S. A Atkinson, D. A Hanley, D. S Ooi, L. Ward, N. Barrowman, M. Fang, et al. Efficacy of food fortification on serum 25-hydroxyvitamin D concentrations: systematic review Am. J. Clinical Nutrition, December 1, 2008; 88(6): 1528 - 1534. [Abstract] [Full Text] [PDF] |
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K. D Cashman, T. R Hill, A. J Lucey, N. Taylor, K. M Seamans, S. Muldowney, A. P FitzGerald, A. Flynn, M. S Barnes, G. Horigan, et al. Estimation of the dietary requirement for vitamin D in healthy adults Am. J. Clinical Nutrition, December 1, 2008; 88(6): 1535 - 1542. [Abstract] [Full Text] [PDF] |
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W. A. van Staveren, J. M. Steijns, and L. C.P.G.M. de Groot Dairy Products as Essential Contributors of (Micro-) Nutrients in Reference Food Patterns: An Outline for Elderly People J. Am. Coll. Nutr., December 1, 2008; 27(6): 747S - 754S. [Abstract] [Full Text] [PDF] |
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C. H Halsted Perspectives on obesity and sweeteners, folic acid fortification and vitamin D requirements Fam. Pract., December 1, 2008; 25(suppl_1): i44 - i49. [Abstract] [Full Text] [PDF] |
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C. L. Wagner, F. R. Greer, and and the Section on Breastfeeding and Committee on Prevention of Rickets and Vitamin D Deficiency in Infants, Children, and Adolescents Pediatrics, November 1, 2008; 122(5): 1142 - 1152. [Abstract] [Full Text] [PDF] |
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D.-H. Manicourt and J.-P. Devogelaer Urban Tropospheric Ozone Increases the Prevalence of Vitamin D Deficiency among Belgian Postmenopausal Women with Outdoor Activities during Summer J. Clin. Endocrinol. Metab., October 1, 2008; 93(10): 3893 - 3899. [Abstract] [Full Text] [PDF] |
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S. Pilz, W. Marz, B. Wellnitz, U. Seelhorst, A. Fahrleitner-Pammer, H. P. Dimai, B. O. Boehm, and H. Dobnig Association of Vitamin D Deficiency with Heart Failure and Sudden Cardiac Death in a Large Cross-Sectional Study of Patients Referred for Coronary Angiography J. Clin. Endocrinol. Metab., October 1, 2008; 93(10): 3927 - 3935. [Abstract] [Full Text] [PDF] |
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D. E. Wallis, S. Penckofer, and G. W. Sizemore The "Sunshine Deficit" and Cardiovascular Disease Circulation, September 30, 2008; 118(14): 1476 - 1485. [Full Text] [PDF] |
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R. Scragg and C. A. Camargo Jr. Frequency of Leisure-Time Physical Activity and Serum 25-Hydroxyvitamin D Levels in the US Population: Results from the Third National Health and Nutrition Examination Survey Am. J. Epidemiol., September 15, 2008; 168(6): 577 - 586. [Abstract] [Full Text] [PDF] |
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R. Scragg and C. A. Camargo Jr Scragg and Camargo Respond to "Physical Activity and Vitamin D" Am. J. Epidemiol., September 15, 2008; 168(6): 590 - 591. [Full Text] [PDF] |
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J. H. White Vitamin D Signaling, Infectious Diseases, and Regulation of Innate Immunity Infect. Immun., September 1, 2008; 76(9): 3837 - 3843. [Full Text] [PDF] |
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R. P. Heaney Nutrients, Endpoints, and the Problem of Proof J. Nutr., September 1, 2008; 138(9): 1591 - 1595. [Full Text] [PDF] |
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S. Pilz, H. Dobnig, J. E. Fischer, B. Wellnitz, U. Seelhorst, B. O. Boehm, and W. Marz Low Vitamin D Levels Predict Stroke in Patients Referred to Coronary Angiography Stroke, September 1, 2008; 39(9): 2611 - 2613. [Abstract] [Full Text] [PDF] |
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B. J. Jones and P. J. Twomey Issues with vitamin D in routine clinical practice Rheumatology, September 1, 2008; 47(9): 1267 - 1268. [Full Text] [PDF] |
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M. L. Melamed, E. D. Michos, W. Post, and B. Astor 25-Hydroxyvitamin D Levels and the Risk of Mortality in the General Population Arch Intern Med, August 11, 2008; 168(15): 1629 - 1637. [Abstract] [Full Text] [PDF] |
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S.-M. Orton, A. P Morris, B. M Herrera, S. V Ramagopalan, M. R Lincoln, M. J Chao, R. Vieth, A D. Sadovnick, and G. C Ebers Evidence for genetic regulation of vitamin D status in twins with multiple sclerosis Am. J. Clinical Nutrition, August 1, 2008; 88(2): 441 - 447. [Abstract] [Full Text] [PDF] |
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A. Prentice, G. R Goldberg, and I. Schoenmakers Vitamin D across the lifecycle: physiology and biomarkers Am. J. Clinical Nutrition, August 1, 2008; 88(2): 500S - 506S. [Abstract] [Full Text] [PDF] |
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E. A Yetley Assessing the vitamin D status of the US population Am. J. Clinical Nutrition, August 1, 2008; 88(2): 558S - 564S. [Abstract] [Full Text] [PDF] |
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B. Hintzpeter, C. Scheidt-Nave, M. J. Muller, L. Schenk, and G. B. M. Mensink Higher Prevalence of Vitamin D Deficiency Is Associated with Immigrant Background among Children and Adolescents in Germany J. Nutr., August 1, 2008; 138(8): 1482 - 1490. [Abstract] [Full Text] [PDF] |
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S. Mark, K. Gray-Donald, E. E. Delvin, J. O'Loughlin, G. Paradis, E. Levy, and M. Lambert Low Vitamin D Status in a Representative Sample of Youth From Quebec, Canada Clin. Chem., August 1, 2008; 54(8): 1283 - 1289. [Abstract] [Full Text] [PDF] |
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M. L Neuhouser, B. Sorensen, B. W Hollis, A. Ambs, C. M Ulrich, A. McTiernan, L. Bernstein, S. Wayne, F. Gilliland, K. Baumgartner, et al. Vitamin D insufficiency in a multiethnic cohort of breast cancer survivors Am. J. Clinical Nutrition, July 1, 2008; 88(1): 133 - 139. [Abstract] [Full Text] [PDF] |
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D. Wagner, G. Sidhom, S. J. Whiting, D. Rousseau, and R. Vieth The Bioavailability of Vitamin D from Fortified Cheeses and Supplements Is Equivalent in Adults J. Nutr., July 1, 2008; 138(7): 1365 - 1371. [Abstract] [Full Text] [PDF] |
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R. Mehrotra, D. Kermah, M. Budoff, I. B. Salusky, S. S. Mao, Y. L. Gao, J. Takasu, S. Adler, and K. Norris Hypovitaminosis D in Chronic Kidney Disease Clin. J. Am. Soc. Nephrol., July 1, 2008; 3(4): 1144 - 1151. [Abstract] [Full Text] [PDF] |
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H. Dobnig, S. Pilz, H. Scharnagl, W. Renner, U. Seelhorst, B. Wellnitz, J. Kinkeldei, B. O. Boehm, G. Weihrauch, and W. Maerz Independent Association of Low Serum 25-Hydroxyvitamin D and 1,25-Dihydroxyvitamin D Levels With All-Cause and Cardiovascular Mortality Arch Intern Med, June 23, 2008; 168(12): 1340 - 1349. [Abstract] [Full Text] [PDF] |
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M. F Holick Deficiency of sunlight and vitamin D BMJ, June 14, 2008; 336(7657): 1318 - 1319. [Full Text] [PDF] |
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J. L Sievenpiper, E. A McIntyre, M. Verrill, R. Quinton, and S. H S Pearce Unrecognised severe vitamin D deficiency BMJ, June 14, 2008; 336(7657): 1371 - 1374. [Full Text] [PDF] |
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L. Gehrig, J. Lane, and M. I. O'Connor Osteoporosis: Management and Treatment Strategies for Orthopaedic Surgeons J. Bone Joint Surg. Am., June 1, 2008; 90(6): 1362 - 1374. [Full Text] [PDF] |
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C. M. Gordon, H. A. Feldman, L. Sinclair, A. L. Williams, P. K. Kleinman, J. Perez-Rossello, and J. E. Cox Prevalence of Vitamin D Deficiency Among Healthy Infants and Toddlers Arch Pediatr Adolesc Med, June 1, 2008; 162(6): 505 - 512. [Abstract] [Full Text] [PDF] |
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A. J. Rovner and K. O. O'Brien Hypovitaminosis D Among Healthy Children in the United States: A Review of the Current Evidence Arch Pediatr Adolesc Med, June 1, 2008; 162(6): 513 - 519. [Abstract] [Full Text] [PDF] |
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R. M Lucas, A. J McMichael, B. K Armstrong, and W. T Smith Estimating the global disease burden due to ultraviolet radiation exposure Int. J. Epidemiol., June 1, 2008; 37(3): 654 - 667. [Abstract] [Full Text] [PDF] |
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M. L. Melamed, P. Muntner, E. D. Michos, J. Uribarri, C. Weber, J. Sharma, and P. Raggi Serum 25-Hydroxyvitamin D Levels and the Prevalence of Peripheral Arterial Disease: Results from NHANES 2001 to 2004 Arterioscler Thromb Vasc Biol, June 1, 2008; 28(6): 1179 - 1185. [Abstract] [Full Text] [PDF] |
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S. A. Bowden, R. F. Robinson, R. Carr, and J. D. Mahan Prevalence of Vitamin D Deficiency and Insufficiency in Children With Osteopenia or Osteoporosis Referred to a Pediatric Metabolic Bone Clinic Pediatrics, June 1, 2008; 121(6): e1585 - e1590. [Abstract] [Full Text] [PDF] |
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L. Rejnmark, P. Vestergaard, L. Heickendorff, and L. Mosekilde Plasma 1,25(OH)2D levels decrease in postmenopausal women with hypovitaminosis D. Eur. J. Endocrinol., April 1, 2008; 158(4): 571 - 576. [Abstract] [Full Text] [PDF] |
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G. Beastall and S. Rainbow Vitamin D Reinvented: Implications for Clinical Chemistry Clin. Chem., April 1, 2008; 54(4): 630 - 632. [Full Text] [PDF] |
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J. C. McCann and B. N. Ames Is there convincing biological or behavioral evidence linking vitamin D deficiency to brain dysfunction? FASEB J, April 1, 2008; 22(4): 982 - 1001. [Abstract] [Full Text] [PDF] |
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S T Weiss and A A Litonjua Author's reply Thorax, March 1, 2008; 63(3): 293 - 293. [Full Text] [PDF] |
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E. T Aasheim, D. Hofso, J. Hjelmesaeth, K. I Birkeland, and T. Bohmer Vitamin status in morbidly obese patients: a cross-sectional study Am. J. Clinical Nutrition, February 1, 2008; 87(2): 362 - 369. [Abstract] [Full Text] [PDF] |
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T. J. Wang, M. J. Pencina, S. L. Booth, P. F. Jacques, E. Ingelsson, K. Lanier, E. J. Benjamin, R. B. D'Agostino, M. Wolf, and R. S. Vasan Vitamin D Deficiency and Risk of Cardiovascular Disease Circulation, January 29, 2008; 117(4): 503 - 511. [Abstract] [Full Text] [PDF] |
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A. H. Lichtenstein, H. Rasmussen, W. W. Yu, S. R. Epstein, and R. M. Russell Modified MyPyramid for Older Adults J. Nutr., January 1, 2008; 138(1): 5 - 11. [Abstract] [Full Text] [PDF] |
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S. A Talwar, J. F Aloia, S. Pollack, and J. K Yeh Dose response to vitamin D supplementation among postmenopausal African American women Am. J. Clinical Nutrition, December 1, 2007; 86(6): 1657 - 1662. [Abstract] [Full Text] [PDF] |
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A. J Rovner, V. A Stallings, J. I Schall, M. B Leonard, and B. S Zemel Vitamin D insufficiency in children, adolescents, and young adults with cystic fibrosis despite routine oral supplementation Am. J. Clinical Nutrition, December 1, 2007; 86(6): 1694 - 1699. [Abstract] [Full Text] [PDF] |
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E. Hypponen, S. Turner, P. Cumberland, C. Power, and I. Gibb Serum 25-Hydroxyvitamin D Measurement in a Large Population Survey with Statistical Harmonization of Assay Variation to an International Standard J. Clin. Endocrinol. Metab., December 1, 2007; 92(12): 4615 - 4622. [Abstract] [Full Text] [PDF] |
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M. J. Rowling, C. Gliniak, J. Welsh, and J. C. Fleet High Dietary Vitamin D Prevents Hypocalcemia and Osteomalacia in CYP27B1 Knockout Mice J. Nutr., December 1, 2007; 137(12): 2608 - 2615. [Abstract] [Full Text] [PDF] |
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R. Bouillon, A. W. Norman, P. Lips, R. C. Cava, A. N. D. Javier, W. R. Howe, R. Dellavalle, G. I. Baroncelli, and M. F. Holick Vitamin D Deficiency N. Engl. J. Med., November 8, 2007; 357(19): 1980 - 1982. [Full Text] [PDF] |
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D. M. Freedman, A. C. Looker, S.-C. Chang, and B. I. Graubard Prospective Study of Serum Vitamin D and Cancer Mortality in the United States J Natl Cancer Inst, November 7, 2007; 99(21): 1594 - 1602. [Abstract] [Full Text] [PDF] |
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E. Giovannucci Can Vitamin D Reduce Total Mortality? Arch Intern Med, September 10, 2007; 167(16): 1709 - 1710. [Full Text] [PDF] |
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S. M Kimball, M. R Ursell, P. O'Connor, and R. Vieth Safety of vitamin D3 in adults with multiple sclerosis Am. J. Clinical Nutrition, September 1, 2007; 86(3): 645 - 651. [Abstract] [Full Text] [PDF] |
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