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Vitamin D plays a critical role in many physiological functions, including calcium metabolism and musculoskeletal health. This commentary aims to explore the intricate relationships among skin complexion, race, and 25-hydroxyvitamin D (25[OH]D) levels, focusing on challenges the Endocrine Society encountered during clinical practice guideline development. Given that increased melanin content reduces 25(OH)D production in the skin in response to UV light, the guideline development panel addressed the potential role for 25(OH)D screening in individuals with dark skin complexion. The panel discovered that no randomized clinical trials have directly assessed vitamin D related patient-important outcomes based on participants' skin pigmentation, although race and ethnicity often served as presumed proxies for skin pigmentation in the literature. In their deliberations, guideline panel members and selected Endocrine Society leaders underscored the critical need to distinguish between skin pigmentation as a biological variable and race and ethnicity as socially determined constructs. This differentiation is vital to maximize scientific rigor and, thus, the validity of resulting recommendations. Lessons learned from the guideline development process emphasize the necessity of clarity when incorporating race and ethnicity into clinical guidelines. Such clarity is an essential step toward improving health outcomes and ensuring equitable healthcare practices., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com. See the journal About page for additional terms.)

Maternal 25-hydroxyvitamin D (25-OHD) deficiency during pregnancy may increase the risk of preterm and small-for-gestational age (SGA) birth, but studies report conflicting results. We used a multicenter prospective cohort of 2813 pregnant women assessed for 25-OHD levels in the first trimester of pregnancy to investigate the association between maternal 25-OHD concentrations and risks of preterm birth (<37 weeks) and SGA (birthweight <10th percentile). Odds ratios were adjusted (aOR) for potential cofounders overall and among women with light and dark skin separately, based on the Fitzpatrick scale. 25-OHD concentrations were <20 ng/mL for 45.1% of the cohort. A total of 6.7% of women had a preterm birth. The aOR for preterm birth associated with the 1st quartile of 25-OHD concentrations compared to the 4th quartile was 1.53 (95% confidence interval (CI): 0.97-2.43). In stratified analyses, an association was observed for women with darker skin (aOR = 2.89 (95% CI: 1.02-8.18)), and no association with lighter skin. A total of 11.9% of births were SGA and there was no association overall or by skin color. Our results do not provide support for an association between maternal first trimester 25-OHD deficiency and risk of preterm or SGA birth overall; the association with preterm birth risk among women with darker skin requires further investigation.

Aim: To investigate vitamin D status and its determinants in school-aged children living in Auckland, New Zealand., Methods: Healthy children (n=507) aged 8-11 years were recruited from six primary schools to include a range of ethnicities and sociodemographic characteristics. Finger-prick blood spots were collected and analysed for capillary 25-hydroxyvitamin D (25(OH)D). Weight and percentage of body fat (%BF) were measured using the InBody 230 (Biospace Co. Ltd., Seoul, Korea). Information related to ethnicity, skin colour, physical activity and sun exposure were sought from parents through a questionnaire., Results: Mean±standard deviation (SD) 25(OH)D concentration were 64±21 nmol/L, with 31% of the population presenting with 25(OH)D≥75nmol/L, 41% 50-75nmol/L and 28%<50nmol/L. Capillary 25(OH)D was significantly higher in New Zealand European compared to all other ethnic groups (75±20nmol/L, P<0.001). As expected, children with dark/brown skin colour had lower 25(OH)D levels compared to other skin colour categories (51±18nmol/L, P<0.001). Using multiple logistic regression analysis, determinants of 25(OH)D were %BF and ethnicity., Conclusion: Approximately one-third of this population had 25(OH)D<50nmol/L. Determinants of a 25(OH)D<50nmol/L included %BF and ethnicity. Wintertime serum 25(OH)D was highly variable. There are some children at high risk of 25(OH)D<50nmol/L for whom supplementation may be considered., Competing Interests: Nil.

The vitamin D-folate hypothesis has been proposed as an explanation for the evolution of human skin pigmentation. According to this hypothesis, a darkened skin pigment was adapted by early human populations living in equatorial Africa to protect against photodegradation of bioavailable folate by ultraviolet radiation (UVR). As humans moved away from the equator to more northern latitudes and occupied regions of lower UVR exposure and greater seasonal variation, however, depigmentation occurred to allow for adequate biosynthesis of vitamin D. Vitamin D and folate are both recognized for their evolutionary importance in healthy pregnancy and early childhood development. More recently, evidence has emerged demonstrating the importance of both vitamin D and folate in vascular health via their effects in reducing oxidative stress and improving nitric oxide (NO) bioavailability. Thus, populations with darkened skin pigmentation may be at elevated risk of vascular dysfunction and cardiovascular disease in low UVR environments due to hypovitaminosis D; particularly important as darkly-pigmented African-Americans represent an at-risk population for cardiovascular disease. Conversely, lightly pigmented populations in high UVR environments may be at risk of deleterious vascular effects of UVR-induced folate degradation. The focus of this review is to explore the currently available literature regarding the potential role of UVR in vascular health via its differential effects on vitamin D and folate metabolism, as well as the interaction between skin pigmentation, genetics, and environment in modulating the vascular influence of UVR exposure.

Background: Estimation of the dietary requirements for vitamin D is crucial from a public health perspective in providing a framework for the prevention of vitamin D deficiency. It has been shown that pooling individual participant-level data (IPD) from selected randomised controlled trials (RCTs) of white children and adults facilitated the generation of more accurate estimates of the vitamin D requirement. Recent RCT data suggest the vitamin D requirement of dark-skinned, particularly black, individuals, an at-risk group of vitamin D deficiency, is greater than those of white counterparts. Thus, we wished to develop a study protocol for the conduct of an IPD-level meta-analysis of vitamin D requirements using data from appropriate vitamin D RCTs in dark-skinned population subgroups., Methods: The study protocol details the steps needed within such an IPD meta-analysis which will include its registration, constituent systematic review to identify all appropriate RCTs on the basis of pre-specified eligibility criteria, the associated data collection, handling, and synthesis, as well as checking the integrity of the IPD, followed by implementation of a one/two-stage IPD meta-analysis and derivation of vitamin D requirement estimates., Discussion: As dark-skinned population subgroups are at increased risk of vitamin D deficiency, further investigation of dietary recommendations for vitamin D in these subgroups is needed. We strongly believe that application of an IPD-based meta-analysis is a highly strategic approach by which to undertake some of this further investigation. Such IPD-based analysis, however, will need collaboration across the principal investigators of the identified RCTs meeting with the eligibility criteria, and the availability of this study protocol will be important to highlight the potential of IPD-based analysis for estimation of the dietary requirement for vitamin D for this particular population subgroup as well as for other at-risk target populations., Systematic Review Registration: PROSPERO International Prospective Register of Systematic Reviews (registration number: CRD42018092343).

We thank Elias and Williams for their interest in our review [...].

In response to a recent article by Jones et al. (Nutrients 10: 554⁻568, 2018) [1], we agree that three distinctive features evolved in Homo erectus prior to the emergence of modern humans.[...].

Objectives: The aim of the study was to evaluate vitamin D status and effects of vitamin D intervention on bone mineral density (BMD) and content (BMC) in children with fair and dark skin in Sweden during winter., Methods: In a 2-center prospective double-blinded randomized intervention study 5- to 7-year-old children (n = 206) with fair and dark skin in Sweden (55°N-63°N) received daily vitamin D supplements of 25 μg, 10 μg, or placebo (2 μg) during 3 winter months. We measured BMD and BMC for total body (TB), total body less head (TBLH), femoral neck (FN), and spine at baseline and 4 months later. Intake of vitamin D and calcium, serum 25-hydroxy vitamin D (S-25[OH]D), and related parameters were analyzed., Results: Despite lower S-25(OH)D in dark than fair-skinned children, BMD of TB (P = 0.012) and TBLH (P = 0.002) and BMC of TBLH (P = 0.04) were higher at baseline and follow-up in those with dark skin. Delta (Δ) BMD and BMC of TB and TBLH did not differ between intervention and placebo groups, but FN-BMC increased more among dark-skinned children in the 25 μg (P = 0.038) and 10 μg (P = 0.027) groups compared to placebo. We found no associations between Δ S-25(OH)D, P-parathyroid hormone, P-alkaline phosphatase, and Δ BMD and BMC, respectively., Conclusions: BMD and BMC remained higher in dark- than fair-skinned children despite lower vitamin D status. Even though no difference in general was found in BMD or BMC after vitamin D intervention, the increase in FN-BMC in dark-skinned children may suggest an influence on bone in those with initially insufficient vitamin D status.

Greater skin pigmentation reduces dose equivalent cutaneous vitamin D3 production, potentially impacting lifetime vitamin D status and fracture risk. We show that melanin density was positively associated with 25-hydroxyvitamin D and total body bone mineral density. These relationships were partially explained by greater sun exposure due to more permissive skin phenotype., Introduction: Higher cutaneous melanin reduces vitamin D3 production. This may impact lifetime vitamin D status and increase fracture risk. This study aimed to describe the relationship between spectrophotometrically determined constitutive melanin density, osteoporotic risk factors and potential intermediaries in a cohort of exclusively older Caucasian adults., Methods: One thousand seventy-two community-dwelling adults aged 50-80 years had constitutive melanin density quantified using spectrophotometry. Sun exposure, skin phenotype, non-melanoma skin cancer (NMSC) prevalence and smoking status were assessed by questionnaire. Bone mineral density (BMD), falls risk, physical activity and 25-hydroxyvitamin D were measured using DXA, the short form Physiological Profile Assessment, pedometer and radioimmunoassay, respectively., Results: Higher melanin density was independently associated with greater ability to tan (RR = 1.27, p < 0.001), less propensity to sunburn (RR = 0.92, p < 0.001), fewer lifetime sunburns (RR = 0.94, p = 0.01), current smoking (RR = 1.41, p < 0.001), female sex (RR = 1.24, p < 0.001) and less photodamage (RR = 0.98, p = 0.01). The associations between melanin density and sun exposure (RR = 1.05-1.11, p < 0.001-0.01), sun protection behaviours (RR = 0.89, p < 0.001) and NMSC prevalence (RR = 0.75, p = 0.001) were no longer significant after taking into account skin phenotype and sun exposure, respectively. 25-Hydroxyvitamin D was strongly associated with higher melanin density (β = 1.71-2.05, p = 0.001). The association between melanin density and total body BMD (β = 0.007, p = 0.04) became non-significant after adjustment for 25-hydroxyvitamin D. There was no association between melanin density and physical activity, falls risk or BMD at other sites., Conclusions: Our data support a model of higher constitutive melanin density underpinning a less photosensitive skin phenotype, permitting greater sun exposure with fewer sequelae and yielding higher 25-hydroxyvitamin D and, potentially, total body BMD.

The evidence for a relationship between serum vitamin D levels and nonskeletal health outcomes is inconsistent. The validity of single or predicted measurements of 25-hydroxyvitamin D (25(OH)D) concentration is unknown, as levels of this biomarker are highly seasonally variable. We compared models of 25(OH)D measured at baseline, at multiple time points throughout the year, and averaged over the year among 309 persons in Toronto, Ontario, Canada (43°N latitude) during 2009-2013. Information and blood samples were collected every 2 months. Baseline and average 25(OH)D concentrations were correlated (r = 0.88). Major factors associated with 25(OH)D level were similar across models and included race/ethnicity (concentrations in non-European groups were lower than those in Europeans), vitamin D supplement use of ≥1,000 IU/day (18.9 nmol/L (95% confidence interval (CI): 16.1, 21.8) vs. no supplement use in a full data set with all factors), and the presence of the group-specific component/vitamin D binding protein gene (GC/DBP) rs4588 functional polymorphism (AA vs. CC: -16.7 nmol/L (95% CI: -26.2, -7.1); CA vs. CC: -10.7 nmol/L (95% CI: -14.9, -6.5)). Most factors had similar associations in Europeans and non-Europeans. Genetic factors may play a greater role in average 25(OH)D concentrations. Prediction models for 25(OH)D are challenging and population-specific, but use of genetic factors along with a few common population-relevant, quantifiable nongenetic factors with strong associations may be the most feasible approach to vitamin D assessment over time., (© The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The current study examined the relationship between vitamin D status and muscle strength in young healthy adults: residents (>6 months) and newcomers (0-3 months), originally from sunny climate countries but currently living in the northeast of Scotland. Our longitudinal data found a positive, albeit small, relationship between vitamin D status and knee extensor isometric strength., Introduction: Vitamin D has been suggested to play a role in muscle health and function, but studies so far have been primarily in older populations for falls prevention and subsequent risk of fractures., Methods: Vitamin D status was assessed in a healthy young adults from sunny climate countries (n = 71, aged 19-42 years) with 56% seen within 3 months of arriving in Aberdeen [newcomers; median (range) time living in the UK = 2 months (9-105 days)] and the remainder resident for >6 months [residents; 23 months (6-121 months)]. Participants attended visits every 3 months for 15 months. At each visit, fasted blood samples were collected for analysis of serum 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH), carboxy-terminal collagen crosslinks (CTX) and N-terminal propeptide of type I collagen (P1NP). Maximal voluntary contractions (MVC) were performed for grip strength (both arms) and for maximal isometric strength of the knee extensors (right knee)., Results: There were small seasonal variations in 25(OH)D concentrations within the newcomers and residents, but no seasonal variation in bone turnover markers. There was a positive, albeit small, association between 25(OH)D and knee extensor maximal isometric strength. Mixed modelling predicted that for each 1 nmol/L increase in 25(OH)D, peak torque would increase by 1 Nm (p = 0.04)., Conclusions: This study suggests that vitamin D may be important for muscle health in young adults migrating from sunnier climates to high latitudes, yet the potential effect is small.

Vitamin D is vital for bone health and its deficiency deemed as a disease of the past has re-emerged as an important health concern. Exposure of the skin to solar ultraviolet B radiation is the major source of vitamin D and only a small proportion is derived from dietary intake. We review the various factors that influence the cutaneous synthesis of vitamin D and the recommendations regarding safe sun exposure and dietary supplementation to achieve adequate vitamin D levels proposed for optimal bone health., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/)

Aim: We aim to investigate vitamin D (25OHD) levels in children with or without type 1 diabetes (T1D) according to latitude and skin color., Methods: We compared 25OHD levels in children with T1D living in Piedmont, of Caucasian or Moroccan origin, with healthy control subjects matched for age and ethnicity. Data of resident children in Morocco, with and without T1D, were used for comparison., Results: Caucasian (21.4±1.5 vs. 24.0±0.5 ng/mL, P<0.05) and Moroccan children with T1D (12.0±2.6 vs. 17.1±1.7 ng/mL, P<0.05) living in Piedmont had lower 25OHD levels than their counterparts without diabetes. Moroccan children living in Morocco with and without T1D had similar 25OHD levels. Vitamin D deficiency was associated with T1D in Caucasian and Moroccan children living in Piedmont (OR: 1.720, CI95% 1.034-2.860, P<0.03), CONCLUSION: Lower vitamin D levels were associated with T1D in Piedmont. Further studies are necessary to explain a possible relationship between vitamin D and T1D.

Background: It has been hypothesised that light skin pigmentation has arisen to ensure adequate levels of vitamin D as human populations moved out of Africa and into higher latitudes. Vitamin D, which is primarily obtained through exposure to sunlight (specifically ultraviolet radiation B (UVR-B)), has been inversely associated with several complex diseases. Greater sun exposure, on the other hand, is a well-known cause of skin cancer. The potential of UVR to be beneficial for some health outcomes but detrimental for others has prompted a public health debate on how to balance the positive and negative consequences of sun exposure. In this study we aimed to determine the validity of the evolutionary hypothesis linking lighter skin with higher vitamin D concentrations in a European population. Additionally, we aimed to examine the influence of pigmentation on personal behaviour towards sunlight exposure and the effects of this behaviour on vitamin D., Methods: We combined genetic variants strongly associated with skin colour, tanning or freckling to create genetic scores for each of these phenotypes. We examined the association of the scores with pigmentary traits, sun exposure and serum 25-hydroxyvitamin D (25(OH)D) levels among children of the Avon Longitudinal Study of Parents and Children (ALSPAC, N = 661 to 5649)., Results: We found that fairer-skinned children, i.e. those with higher pigmentation score values, had higher levels of 25(OH)D (0.6 nmol/l; 95% CI 0.2, 1.0; per unit increase in skin colour score; N = 5649). These children also used more protection against the damaging effects of UVR., Conclusions: In this population taking protective measures against sunburn and skin cancer does not seem to remove the positive effect that having a less pigmented skin has on vitamin D production. Our findings require further replication as skin pigmentation showed only a small effect on circulating 25(OH)D.

Exposure to sunlight is a major source of vitamin D for most people yet public health advice focuses overwhelmingly on avoiding exposure of unprotected skin because of the risks oferythema and skin cancer. We have calculated the exposure required to gain a number of proposed oral-equivalent doses of vitamin D, as functions of latitude, season, skin type and skin area exposed, together with the associated risk of erythema, expressed in minimum erythema doses. The model results show that the current recommended daily intake of 400 IU is readily achievable through casual sun exposure in the midday lunch hour, with no risk of erythema, for all latitudes some of the year and for all the year at some (low) latitudes. At the higher proposed vitamin D dose of 1000 IU lunchtime sun exposure is still a viable route to the vitamin, but requires the commitment to expose greater areas of skin, or is effective for a shorter period of the year. The highest vitamin D requirement considered was 4000 IU per day. For much of the globe and much of the year, this is not achievable in a lunchtime hour and where it is possible large areas of skin must be exposed to prevent erythema. When the only variable considered was skin type, latitudinal and seasonal limits on adequate vitamin D production were more restrictive for skin type 5 than skin type 2.

Background: Long-standing concerns over the vitamin D status of South Asian adults in the U.K. require studies using statistically valid sample sizes to measure annual variation and contributory lifestyle factors., Objectives: To measure annual variation in the vitamin D status of U.K. South Asians, to determine the associated lifestyle influences, and to compare these with a similar study of white adults., Methods: A single-centre, prospective cohort study measuring circulating 25-hydroxyvitamin D [25(OH)D], sunlight exposure levels and lifestyle factors for 1 year in 125 ambulant South Asian adults with sun-reactive skin type V, aged 20-60 years, in Greater Manchester, U.K. (53·5°N)., Results: The 25(OH)D levels of South Asians were alarmingly low. In summer, their median 25(OH)D level was 9·0 ng mL(-1) , [interquartile range (IQR) 6·7-13·1], falling to 5·8 ng mL(-1) (IQR 4·0-8·1) in winter. This compared with values in the white population of 26·2 ng mL(-1) (IQR 19·9-31·5) in summer and 18·9 ng mL(-1) IQR (11·6-23·7) in winter. Median daily dietary vitamin D was lower in South Asians (1·32 μg vs. 3·26 μg for white subjects) and was compounded by low supplement use. Despite similar times spent outdoors, ultraviolet (UV) dosimeters recorded lower personal UV exposure among South Asians, indicating sun avoidance when outside, while sun exposure diaries recorded lower amounts of skin surface exposure., Conclusions: The majority of South Asians never reached sufficiency in vitamin D status. Lifestyle differences, with lower oral intake, sun exposure and rates of cutaneous production due to darker skin, indicate that standard advice on obtaining sufficient vitamin D needs modification for the South Asian community in the U.K., (© 2013 British Association of Dermatologists.)

Vitiligo is a common pigmentary disorder caused by the destruction of functional melanocytes. Vitamin D is an essential hormone synthesized in the skin and is responsible for skin pigmentation. Low levels of vitamin D have been observed in vitiligo patients and in patients with other autoimmune diseases. Therefore, the relationship between vitamin D and vitiligo needs to be investigated more thoroughly. We reviewed the literature to date regarding the role of vitamin D in skin pigmentation. Our review revealed that vitamin D deficiency has been identified in many conditions, including premature and dysmature birth, pigmented skin, obesity, advanced age, and malabsorption. Vitamin D increases melanogenesis and the tyrosinase content of cultured human melanocytes by its antiapoptotic effect. However, a few growth-inhibitory effects on melanocytes were also reported. Vitamin D regulates calcium and bone metabolism, controls cell proliferation and differentiation, and exerts immunoregulatory activities. Vitamin D exerts its effect via a nuclear hormone receptor for vitamin D. The topical application of vitamin D increased the number of L-3,4-dihydroxyphenylalanine-positive melanocytes. The topical application of vitamin D yields significant results when used in combination with phototherapy and ultraviolet exposure to treat vitiligo in humans. Vitamin D decreases the expression of various cytokines that cause vitiligo. In conclusion, application of vitamin D might help in preventing destruction of melanocytes thus causing vitiligo and other autoimmune disorders. The association between low vitamin D levels and the occurrence of vitiligo and other forms of autoimmunity is to be further evaluated.

Low maternal vitamin D status during pregnancy may have negative consequences for both mother and child. There are few studies of vitamin D status and its determinants in pregnant women living at northern latitudes. Thus, the present study investigates vitamin D status and its determinants during the third trimester of women living in Sweden (latitudes 57-58°N). A total of ninety-five fair-skinned pregnant women had blood taken between gestational weeks 35 and 37. The study included a 4 d food diary and questionnaires on dietary intake, supplement use, sun exposure, skin type, travels to southern latitudes and measure of BMI. Serum 25-hydroxyvitamin D (25(OH)D) was analysed using the chemiluminescence immunoassay. In the third trimester of pregnancy, mean serum concentration of 25(OH)D was 47.4 (sd 18.1) nmol/l (range 10-93 nmol/l). In total, 65% of women had serum 25(OH)D < 50 nmol/l and 17 % < 30 nmol/l. During the winter, 85% of the pregnant women had serum 25(OH)D < 50 nmol/l and 28 % < 30 nmol/l. The main determinants of vitamin D status were as follows: season; use of vitamin D supplements; travels to southern latitudes. Together, these explained 51% of the variation in 25(OH)D. In conclusion, during the winter, the majority of fair-skinned pregnant women had serum 25(OH)D < 50 nmol/l in their third trimester and more than every fourth woman < 30 nmol/l. Higher vitamin D intake may therefore be needed during the winter for fair-skinned pregnant women at northern latitudes to avoid vitamin D deficiency.

Background: In human beings, dark skin requires more exposure to ultraviolet light to synthesize the same amount of vitamin D as lighter skin. It is has been repeatedly shown that at the latitude of the United States there are vitamin D disparities related to skin color. Although inadequate vitamin D status and health disparities have been associated with many of the same diseases, neither nutrition policy nor public health policy in the United States currently recognizes any role at all for vitamin D as a determinant of health disparities., Objective: This study investigated the relationship between health, skin color, and vitamin D nutriture in the US population., Design: The design is cross-sectional, correlational, and can be generalized to the population of the United States., Participants: We used data from 12,505 (unweighted) subjects (3,402 non-Hispanic blacks, 3,143 Mexican Americans, and 5,960 non-Hispanic whites), aged 13 years or older, from the continuous National Health and Nutrition Examination Survey 2003-2006., Main Outcome Measure: Self-rated health, a repeatedly validated indicator of objective health status, was used as a continuous measure of health., Statistical Analyses Performed: Using software appropriate for the complex survey design of the National Health and Nutrition Examination Survey, the study consisted of six regression models, one predicting vitamin D status and five predicting self-rated health., Results: Controlling for the covariates sex, interview language, country of birth, tobacco use, age, body mass index, and leisure exercise as well as the socioeconomic variables education and family income, remaining disparities in self-rated health are greatly reduced or eliminated by controlling for serum 25-hydroxyvitamin D levels., Conclusions: We found that socioeconomic factors are the strongest determinant of skin-color based health disparities in the US population, but that it may not be possible to eliminate health disparities in the United States without eliminating the skin-color-related disparities in vitamin D nutriture., (Copyright © 2013 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.)

Observational studies suggest that people with a high serum 25-hydroxyvitamin D (25(OH)D) concentration may have reduced risk of chronic diseases such as osteoporosis, multiple sclerosis, type 1 diabetes, cardiovascular disease, and some cancers. The AusD Study (A Quantitative Assessment of Solar UV Exposure for Vitamin D Synthesis in Australian Adults) was conducted to clarify the relationships between ultraviolet (UV) radiation exposure, dietary intake of vitamin D, and serum 25(OH)D concentration among Australian adults residing in Townsville (19.3°S), Brisbane (27.5°S), Canberra (35.3°S), and Hobart (42.8°S). Participants aged 18-75 years were recruited from the Australian Electoral Roll between 2009 and 2010. Measurements were made of height, weight, waist:hip ratio, skin, hair, and eye color, blood pressure, and grip strength. Participants completed a questionnaire on sun exposure and vitamin D intake, together with 10 days of personal UV dosimetry and an associated sun-exposure and physical-activity diary that was temporally linked to a blood test for measurement of 25(OH)D concentration. Ambient solar UV radiation was also monitored at all study sites. We collected comprehensive, high-quality data from 1,002 participants (459 males, 543 females) assessed simultaneously across a range of latitudes and through all seasons. Here we describe the scientific and methodological issues considered in designing the AusD Study.

Spatio-temporal patterns in sun exposure underlie variations in skin cancer incidence and vitamin D deficiency, indicate effectiveness of sun protection programs and provide insights into future health risks. From 558 adults across four regions of Australia (Brisbane (27°S), Newcastle (33°S), Geelong and the Western Districts of Victoria (37°S) and Tasmania (43°S)), we collected: self-report data on time-in-the-sun from age 6 years; natural skin color and ethnicity; silicone skin casts (for cumulative skin damage); and serum for vitamin D status. Ambient ultraviolet radiation (UVR) at the location of residence, with time-in-the-sun, was used to calculate a "UVR dose" for each year of life. Individuals maintained their ranking compared to their peers for time-in-the-sun in summer compared to winter and across ages (Spearman rho 0.24-0.84, all P < 0.001). Time-in-the-sun decreased with age in all birth cohorts, and over calendar time. Summer time-in-the-sun increased with increasing latitude (P < 0.001). Seasonal variation in vitamin D status had greater amplitude and vitamin D deficiency increased with increasing latitude. Temporal patterns are consistent with effectiveness of sun protection programs. Higher relative time-in-the-sun persists from childhood through adulthood. Lower summer time-in-the-sun in the warmest location may have implications for predictions of UVR-related health risks of climate change., (© 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.)

Objective: To examine the association between cow's milk intake on both vitamin D and iron stores in healthy urban preschoolers., Methods: Healthy children 2 to 5 years of age were recruited from December 2008 through December 2010 through the TARGet Kids! practice-based research network. Cow's milk intake was measured by parental report. Vitamin D and iron stores were measured by using serum 25-hydroxyvitamin D and ferritin. Bivariate multivariable linear regression was used to examine the effect of cow's milk intake simultaneously on 25-hydroxyvitamin D and serum ferritin. Analyses were stratified by important clinical variables including skin pigmentation, bottle feeding, vitamin D supplementation, and season., Results: Among 1311 children, increasing cow's milk consumption was associated with decreasing serum ferritin (P < .0001) and increasing 25-hydroxyvitamin D (P ≤ .0001). Two cups (500 mL) of cow's milk per day maintained 25-hydroxyvitamin D >75 nmol/L with minimal negative effect on serum ferritin for most children. Children with darker skin pigmentation not receiving vitamin D supplementation during the winter required 3 to 4 cups of cow's milk per day to maintain 25-hydroxyvitamin D >75 nmol/L. Cow's milk intake among children using a bottle did not increase 25-hydroxyvitamin D and resulted in more dramatic decreases in serum ferritin., Conclusions: There is a trade-off between increasing 25-hydroxyvitamin D and decreasing serum ferritin with increasing milk intake. Two cups of cow's milk per day appears sufficient to maintain healthy vitamin D and iron stores for most children. Wintertime vitamin D supplementation was particularly important among children with darker skin pigmentation.

Background: Whether dark skin produces less vitamin D after UVB radiation than fair skin remains controversial., Objective: To compare 25-hydroxyvitamin D [25-(OH)-D] levels after a single UVB exposure in fair (phototype II-III) and black-skinned (phototype VI) volunteers., Methods: Fair-skinned volunteers (n = 20, 4 males/16 females, mean age: 23.2 years) and black-skinned (n = 11, 6 males/5 females, mean age: 23.8 years) received a single total body UVB exposure (0.022 J/cm(2)). The 25-(OH)-D levels were measured on days 0, 2 and 6., Results: On day 0, all volunteers were severely vitamin D deficient. On day 2, 25-(OH)-D levels of fair-skinned volunteers increased significantly (median: 11.9-13.3 ng/ml, p < 0.0001), but not in black-skinned people (median: 8.60-8.55 ng/ml, p = 0.843). Again, on day 6, 25-(OH)-D levels of fair-skinned volunteers increased significantly (median: 11.9-14.3 ng/ml, p < 0.0001), but not in black-skinned people (median: 8.60-9.57 ng/ml, p = 0.375)., Conclusion: This study suggests that skin pigmentation negatively influences vitamin D synthesis., (© 2013 S. Karger AG, Basel.)

Skin cancer is the most common cancer in the United States. Exposure to ultraviolet radiation is a known risk factor for skin cancer but is also the principal means by which the body obtains vitamin D. Several studies have suggested that vitamin D plays a protective role in a variety of internal malignancies. With regard to skin cancer, epidemiologic and laboratory studies suggest that vitamin D and its metabolites may have a similar protective effect. These noncalcemic actions of vitamin D have called into question whether the current recommended intake of vitamin D is too low for optimal health and cancer prevention. Part I will review the role of vitamin D in the epidermis; part II will review the role of vitamin D in keratinocyte-derived tumors to help frame the discussion on the possible role of vitamin D in the prevention of skin cancer., (Copyright © 2012 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

Vitamin D is a fat-soluble steroid hormone that is crucial for human health and has recently generated controversy regarding its role in human health and disease. In this Special Article, we discuss our dermatologic perspective on vitamin D in a question-and-answer format. We discuss methods of obtaining vitamin D, including cutaneous photobiosynthesis, diet, and supplements and include the recent US Institute of Medicine recommendations. Other reviewed topics include the associations among skin pigmentation, climate, photoprotection, and vitamin D levels. We also elaborate on the popular interest in sun exposure as a method of normalizing vitamin D levels in the context of the risks of solar and artificial radiation. We also discuss groups at risk for vitamin D inadequacy, the need for testing serum vitamin D levels, and the role of phototherapy in patients with malabsorption conditions and hypervitaminosis D, with a focus on patients with sarcoidosis. Finally, we summarize our recommendations on vitamin D., (Copyright © 2012 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.)

Background: Reports of clinical rickets are particularly evident in minority infants and children, but only limited analyses of vitamin D are available in this demographic group., Objective: We sought to characterize circulating 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and their determinants, including circulating parathyroid hormone (PTH), total alkaline phosphatase activity (ALP), calcium, and phosphorus, in minority infants and children., Design: We obtained demographic information and blood samples for measurement of PTH, ALP, 25(OH)D, and 1,25(OH)(2)D in >750 6-mo- to 3-y-old children. Dietary intake data were obtained and analyzed., Results: The mean (±SD) 25(OH)D concentration was 66 ± 22 nmol/L (26.3 ± 8.7 ng/dL). A total of 15% of children had 25(OH)D concentrations less than the recommended target threshold of 50 nmol/L. Combined elevations of PTH and ALP occurred in only 2.5% of children. Determinants of 25(OH)D included vitamin D intake, age (decreasing with age), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), formula use (higher intakes), season (greater concentrations in the summer and fall than in the winter and spring), and, inversely, PTH. The mean 1,25(OH)(2)D concentration was 158 ± 58 pmol/L (60.6 ± 22.5 pg/mL), which was consistent with a reference range of 41-274 pmol/L or 15.7-105.5 pg/mL. Determinants for 1,25(OH)(2)D were age (decreasing with age), sex (greater concentrations in girls than in boys), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), and, inversely, serum calcium and phosphorus., Conclusions: Although 15% of subjects were vitamin D insufficient, only 2.5% of subjects had elevations of both PTH and ALP. The greater 25(OH)D concentrations observed with formula use confirm that dietary vitamin D fortification is effective in this demographic group. Circulating 1,25(OH)(2)D is higher in infants than in older children and adults and, in contrast to 25(OH)D, is not directly correlated with nutrient intakes.

Background: Previous studies on ultraviolet radiation (UVR) exposure before and after a diagnosis of cutaneous malignant melanoma (CMM) have been based primarily on questionnaires. Objective measures are needed., Objectives: To assess changes in UVR exposure in patients with CMM using objective surrogate parameters in a descriptive study., Methods: Ten patients recently diagnosed with CMM during the 5 months (autumn and winter) preceding study start in February 2009; 21 patients diagnosed from 12 months to 6 years before study start; and 15 controls, who matched the recently diagnosed patients on age, sex, residential area, constitutive skin type and occupation completed the investigations. UVR exposure before and after diagnosis of CMM was assessed using measures of serum 25-hydro vitamin D [25(OH)D], skin pigmentation and by interviews. Winter 25(OH)D was used as a surrogate parameter of UVR exposure the previous summer - the summer before CMM diagnosis in recently diagnosed patients., Results: Winter 25(OH)D was significantly higher among recently diagnosed patients compared with controls (P = 0·02, R² = 0·60) and patients diagnosed up to 6 years earlier (P = 0·01). The increase in 25(OH)D during the summer after diagnosis was significantly lower for recently diagnosed patients than for controls (P = 0·005, R² = 0·51) and patients diagnosed up to 6 years earlier (P = 0·008). No difference was found in summer 25(OH)D between the groups., Conclusions: Our findings suggest that patients with CMM had a higher UVR exposure the summer before diagnosis than did controls and patients diagnosed up to 6 years earlier, and that after diagnosis UVR exposure fell to the level of controls in patients with CMM., (© 2011 The Authors. BJD © 2011 British Association of Dermatologists 2011.)

Context: UV radiation is responsible for vitamin D synthesis and skin tanning. Longitudinal data relating skin color to vitamin D status are lacking., Objective: Our objective was to determine whether seasonal facial skin color changes are related to changes in 25-hydroxyvitamin D [25(OH)D]., Design and Setting: We conducted a prospective observational cohort study (Aberdeen Nutrition Sunlight and Vitamin D) with five visits over 15 months, starting spring 2006 with an additional visit in spring 2008 at a university medical research center in Scotland, 57° N., Participants: Participants included 314 Caucasian postmenopausal women, age 60-65 yr., Main Outcome Measures: Facial skin color was assessed by skin reflectance and expressed as the individual typology angle (ITA) (higher number indicates paler skin). 25(OH)D was measured by immunoassay., Results: Most women (43%) reported Fitzpatrick skin type III (always burns, always tans), 32% type II, and 25% type I (always burns, never tans). Overall, mean (sd) ITA in degrees were 36.6 (7.7), 38.2 (6.5), and 42.8 (5.3), respectively, for summer, autumn, and winter (P < 0.001). Linear regression showed that a 5° summer-winter change in ITA, was associated with a 15 nmol/liter change in 25(OH)D (P < 0.001) but did not predict winter 25(OH)D. Reported sunscreen use was associated with higher 25(OH)D. Mean (SD) 25(OH)D (nanomoles per liter) but not skin color was lower for the top body mass index quartile (Q4) compared with the other quartiles (summer: Q1, 57.1(19.9); Q4, 49.7 (20.4); P = 0.010)., Conclusions: Skin color change between summer and winter predicts seasonal 25(OH)D change. Low vitamin D status in obese women was not due to reduced sun exposure, suggesting that increased requirements or inaccessibility of vitamin D stores may be responsible.

Summary: We assessed vitamin D status and its correlates in the population-based Canadian Multicentre Osteoporosis Study (CaMos). Results showed that serum 25-hydroxyvitamin D levels <75 nmol/L were common. Given Canada's high latitude, attention should be given to strategies for enhancing vitamin D status in the population., Introduction: Inadequate vitamin D has been implicated as a risk factor for several clinical disorders. We assessed, in a Canadian cohort, vitamin D status and its correlates, based on serum 25-hydroxyvitamin D [25(OH)D], the best functional indicator of vitamin D status., Methods: We studied 577 men and 1,335 women 35+ years from seven cities across Canada in the randomly selected, population-based Canadian Multicentre Osteoporosis Study (CaMos). Participants completed a comprehensive questionnaire. Serum 25(OH)D was measured by immunoassay. Multivariate linear regression modeling assessed the association between 25(OH)D and determinants of vitamin D status., Results: Participants (2.3%) were deficient in 25(OH)D (<27.5 nmol/L); a further 18.1% exhibited 25(OH)D insufficiency (27.5-50 nmol/L). Levels <75 nmol/L were evident in 57.5% of men and 60.7% of women and rose to 73.5% in spring (men) and 77.5% in winter (women); 25(OH)D <50 nmol/L was ≤10% year round for those supplementing with ≥400 IU vitamin D/day but was 43.9% among those not supplementing in winter and spring. The strongest predictors of reduced 25(OH)D for both men and women were winter and spring season, BMI ≥30, non-white ethnicity, and lower vitamin D supplementation and its modification by fall and winter., Conclusions: In this national Canadian cohort, vitamin D levels <75 nmol/L were common, particularly among non-white and obese individuals, and in winter and spring. Vitamin D intake through diet and supplementation and maintenance of normal weight are key modifiable factors for enhancing vitamin D status and thus potentially influencing susceptibility to common chronic diseases., Competing Interests: D. Goltzman has received honoraria from and served on the advisory boards of Amgen, Eli Lilly, Proctor & Gamble, Merck Frosst, Novartis and Servier. D.A. Hanley has received honoraria from Amgen, Proctor & Gamble, sanofi-aventis, Merck Frosst, and Servier. L Greene-Finestone, C Berger, M de Groh, N Hidiroglou, K Sarafin, S Poliquin, J Krieger, and JB Richards have no conflicts of interest.

There is little information on the contribution of modifiable vs nonmodifiable factors to maternal and neonatal vitamin D status in temperate regions of the United States. The purpose of this cross-sectional observation study conducted between December 2006 and February 2008 was to identify associations between observed and measured maternal characteristics and vitamin D status at term in pregnant women and their infants in a multiethnic community in Oakland, CA. Two hundred seventy-five pregnant women aged 18 to 45 years and carrying a singleton fetus were recruited and data from 210 mother-infant pairs were included in analyses. Analysis of covariance identified predictors of maternal and cord serum 25-hydroxyvitamin D [25(OH)D] in a multivariate model considering vitamin D intake, lifestyle factors, and skin pigmentation. Maternal serum 25(OH)D was significantly associated with season of delivery (P=0.0002), average daily D intake (P=0.0008), right upper inner arm pigmentation (P=0.0035), and maternal pre- or early-pregnancy body mass index (calculated as kg/m²) (P=0.0207). The same factors were significant for cord serum 25(OH)D, which was highly correlated with maternal serum 25(OH)D (r=0.79; P<0.0001). During the year, 54% of mothers and 90% of neonates had 25(OH)D <30 ng/mL (<75 nmol/L). Of women taking daily prenatal vitamin/mineral supplements (400 IU vitamin D), 50.7% had serum 25(OH)D <30 ng/mL (<75 nmol/L). In conclusion, 25(OH)D <30 ng/mL (<75 nmol/L) was prevalent in mothers and neonates across racial groups and seasons, and vitamin D status was associated with both modifiable and nonmodifiable risk factors., (Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.)

To investigate the relationship between UV-induced skin photodamage and 25(OH) vitamin D levels, we performed a cross-sectional study in 45 female subjects aged >40. Menopausal status, smoking status, skin cancer history, oral supplement use, and season of blood draw were recorded and serum 25(OH)D measured. A single-blinded, dermatologist evaluated standardized digital facial images for overall photodamage, erythema/telangiectasias, hyperpigmentation, number of lentigines, and wrinkling. Adjusting for age and season of blood collection, women with lower photodamage scores were associated with a 5-fold increased odds of being vitamin D insufficient (OR 5.0, 95% CI: 1.1, 23). Low scores for specific photodamage parameters including erythema/telangiectasias, hyperpigmentation, and wrinkling were also significantly associated with vitamin D insufficiency. Our results suggest an association between skin aging and 25(OH)D levels.

Cutaneous cholecalciferol synthesis has not been considered in making recommendations for vitamin D intake. Our objective was to model the effects of sun exposure, vitamin D intake, and skin reflectance (pigmentation) on serum 25-hydroxyvitamin D (25[OH]D) in young adults with a wide range of skin reflectance and sun exposure. Four cohorts of participants (n = 72 total) were studied for 7-8 wk in the fall, winter, spring, and summer in Davis, CA [38.5 degrees N, 121.7 degrees W, Elev. 49 ft (15 m)]. Skin reflectance was measured using a spectrophotometer, vitamin D intake using food records, and sun exposure using polysulfone dosimeter badges. A multiple regression model (R(2) = 0.55; P < 0.0001) was developed and used to predict the serum 25(OH)D concentration for participants with low [median for African ancestry (AA)] and high [median for European ancestry (EA)] skin reflectance and with low [20th percentile, approximately 20 min/d, approximately 18% body surface area (BSA) exposed] and high (80th percentile, approximately 90 min/d, approximately 35% BSA exposed) sun exposure, assuming an intake of 200 iu/d (5 ug/d). Predicted serum 25(OH)D concentrations for AA individuals with low and high sun exposure in the winter were 24 and 42 nmol/L and in the summer were 40 and 60 nmol/L. Corresponding values for EA individuals were 35 and 60 nmol/L in the winter and in the summer were 58 and 85 nmol/L. To achieve 25(OH)D > or =75 nmol/L, we estimate that EA individuals with high sun exposure need 1300 iu/d vitamin D intake in the winter and AA individuals with low sun exposure need 2100-3100 iu/d year-round.

Unlabelled: We performed a meta-analysis of cross-sectional studies on serum 25(OH)D status globally. Serum 25(OH)D levels on average were 54 nmol/l, were higher in women than men, and higher in Caucasians than in non-Caucasians. There was no trend in serum 25(OH)D level with latitude. Vitamin D deficiency was widespread., Introduction: We studied vitamin D status (expressed as serum 25-hydroxy-vitamin D [25(OH)D]) in native subjects worldwide., Methods: Meta-analysis and meta-regression of studies reporting on 25(OH)D in healthy subjects retrieved from Pubmed, Embase and Web of Science using the terms "serum", "25-hydroxy-vitamin D", "cholecalciferol", and "human". A total of 394 studies were included., Results: The mean 25(OH)D level was 54 nmol/l (95% CI: 52-57 nmol/l). Women had borderline significantly higher 25(OH)D levels than men, and Caucasians had higher levels than non-Caucasians. 25(OH)D levels were higher in subjects aged >15 years than in younger subjects. Unadjusted there was no significant decrease in 25(OH)D with latitude (slope of curve -0.03 +/- 0.12 nmol/l per degree latitude north or south of equator, p = 0.8). There was a significant decline with latitude for Caucasians (-0.69 +/- 0.30 nmol/l per degree, p = 0.02), but not for non-Caucasians (0.03 +/- 0.39 nmol/l per degree, p = 0.14). After adjustment for age, gender, and ethnicity, no overall correlation was present between 25(OH)D and latitude (-0.29 +/- 0.24 nmol/l per degree, p = 0.23)., Conclusion: There was no overall influence of latitude on 25(OH)D. However, in separate analyses 25(OH)D decreased with latitude in Caucasians but not in non-Caucasians. A widespread global vitamin D insufficiency was present compared with proposed threshold levels.

Unlabelled: We examined the relationship between vitamin D and skin color measured by reflectance colorimetry at an exposed and un-exposed site in 321 people. Exposed but not unexposed skin color was associated with better vitamin D status. Sun-exposure was more important than natural skin color in determining vitamin D status in our population., Introduction: Vitamin D is obtained through UV synthesis in the skin where melanin limits its synthesis. Ethnicity is often used as a proxy for skin color, but skin color varies considerably. The relation between quantitative measures of skin color and plasma 25-hydroxyvitamin D (25OHD) concentration has not been well described., Methods: The aim of this study was to determine the association between constitutive (natural) and sun-induced skin color and 25OHD in a group of Pacific People (n = 87) and Europeans (n = 255) living in NZ (46 degrees S) in summer. Plasma 25OHD was determined and sun-induced (outer fore-arm) and constitutive (upper inner-arm) measured by reflectance colorimetry., Results: Mean (SD) 25OHD was significantly higher in Europeans than Pacific People, 88 (31) nmol/L vs. 75 (34) nmol/L, respectively. Based on constitutive skin color, 35% of participants were very light, 45% light, 16% intermediate, 4% tanned, and 0% brown or dark. Skin color at the forearm but not constitutive skin color was a significant predictor of 25OHD. Each 10 degrees lower skin color value at the forearm (more tanning) was associated with a 5 nmol/L higher 25OHD (P < 0.001)., Conclusions: Tanning but not natural skin color was an important determinant of 25OHD. Further study is needed in a population with a higher proportion of darker skin people.

The purpose of this review is to summarize the peer-reviewed literature in relation to sunlight exposure assessment and the validity of using sunlight exposure questionnaires to quantify vitamin D status. There is greater variability in personal ultraviolet (UV) light exposure as the result of personal behavior than as the result of ambient UV light exposure. Although statistically significant, the correlation coefficients for the relation between personal report of sun exposure and ambient UV light measured by dosimetry (assessment of radiation dose) are relatively low. Moreover, the few studies to assess the relation between sunlight measures and serum 25-hydroxyvitamin D show low correlations. These low correlations may not be surprising given that personal factors like melanin content in skin and age also influence cutaneous synthesis of vitamin D. In summary, sunlight exposure questionnaires currently provide imprecise estimates of vitamin D status. Research should be directed to develop more objective, nonintrusive, and economical measures of sunlight exposure to quantify personal vitamin D status.

Background: Vitamin D deficiency or insufficiency has been observed among populations in the northern United States. However, data on the prevalence of vitamin D deficiency in areas of high sun exposure, such as Arizona, are limited., Objective: The purpose of this study was to analyze serum 25-hydroxyvitamin D [25(OH)D] concentrations in residents of southern Arizona and to evaluate predictors of 25(OH)D in this population., Design: Cross-sectional analyses of serum from participants in a colorectal adenoma prevention study were conducted to determine rates of vitamin D deficiency. Participants were categorized into 4 groups on the basis of serum 25(OH)D concentrations: <10.0 ng/mL, > or =10.0 ng/mL and <20.0 ng/mL, > or =20.0 ng/mL and <30.0 ng/mL, and > or =30.0 ng/mL., Results: The mean serum 25(OH)D concentration for the total population was 26.1 +/- 9.1 ng/mL. Of 637 participants, 22.3% had 25(OH)D concentrations >30 ng/mL, 25.4% had concentrations <20 ng/mL, and 2.0% had concentrations <10 ng/mL. Blacks (55.5%) and Hispanics (37.6%) were more likely to have deficient 25(OH)D concentrations (<20 ng/mL) than were non-Hispanic whites (22.7%). Sun exposure had a greater effect on 25(OH)D in whites than in blacks and Hispanics, whereas BMI appeared to be more important in the latter groups., Conclusion: Despite residing in a region with high chronic sun exposure, adults in southern Arizona are commonly deficient in vitamin D deficiency, particularly blacks and Hispanics.

Background: Vitamin D deficiency is common in dark-skinned persons living in northern countries. Vitamin D deficiency during pregnancy may have serious consequences for both mother and child., Objective: The objective was to ascertain the prevalence of vitamin D deficiency in pregnant women of several ethnic backgrounds who were living in The Hague, a large city in the Netherlands., Design: Midwives whose practice was visited by a large number of non-Western immigrants added the assessment of serum 25-hydroxyvitamin D [25(OH)D] to the standard blood test given to women who visited the practice during week 12 of pregnancy. Subsequently, the Municipal Health Service collected additional data from the midwives' files (June 2002 through March 2004): background variables, use of tobacco or alcohol or drugs, and infectious diseases. The women were grouped ethnically as Western, Turkish, Moroccan, and other non-Western., Results: The vitamin D concentrations of 358 women were found in the midwives' files. Of these women, 29% were Western, 22% were Turkish, and 19% were Moroccan. Mean serum 25(OH)D concentrations in Turkish (15.2 +/- 12.1 nmol/L), Moroccan (20.1 +/- 13.5 nmol/L), and other non-Western women (26.3 +/- 25.9 nmol/L) were significantly (P

Concerns about vitamin D have resurfaced in medical and scientific literature because the prevalence of vitamin D deficiency in the United States, particularly among darkly pigmented persons, has increased. The primary goals of this review were to discuss past and current literature and to reassess the dietary reference intake for vitamin D in adults, with particular focus on women during pregnancy and lactation. The appropriate dose of vitamin D during pregnancy and lactation is unknown, although it appears to be greater than the current dietary reference intake of 200-400 IU/d (5-10 microg/d). Doses of < or =10 000 IU vitamin D/d (250 microg/d) for up to 5 mo do not elevate circulating 25-hydroxyvitamin D to concentrations > 90 ng/mL, whereas doses < 1000 IU/d appear, in many cases, to be inadequate for maintaining normal circulating 25-hydroxyvitamin D concentrations of between 15 and 80 ng/mL. Vitamin D plays no etiologic role in cardiac valvular disease, such as that observed in Williams syndrome, and, as such, animal models involving vitamin D intoxication that show an effect on cardiac disease are flawed and offer no insight into normal human physiology. Higher doses of vitamin D are necessary for a large segment of Americans to achieve concentrations equivalent to those in persons who live and work in sun-rich environments. Further studies are necessary to determine optimal vitamin D intakes for pregnant and lactating women as a function of latitude and race.

Painful pathological fractures of the femoral neck and the subtrochanteric region of the femur are reported in two women originating from India. After exclusion of renal or intestinal causes, laboratory data on bone metabolism, scintigraphic and radiographic examinations were characteristic for the presence of secondary hyperparathyroidism. Based on vitamin deficiency and low calcium absorption, disturbed mineralization of bone and increased osteoclastic resorption have apparently led to osteomalacia and subsequent fracturing. Fracture localization necessitated surgical fixation in one patient; conservative treatment including protected weightbearing was effective in the other women. After supplementation of calcium and vitamin D3, levels of parathyroid hormone and scintigraphic alterations returned to normal in both patients. In these two cases, pathological fractures of the hip could be attributed to the presence of secondary hyperparathyroidism based on decreased cutaneous vitamin D synthesis.

We investigated the homeostatic compensation for the lower cutaneous synthesis of vitamin D in heavily melanized persons. Vitamin D2 (50,000 IU) was administered in a single oral dose to 24 young adults, 12 blacks and 12 whites, matched for age, gender, and socioeconomic status. We also included a group of eight healthy elderly white adults as representatives of a population with a nonracial mechanism for decreased cutaneous vitamin D synthesis. Plasma determinants were performed under basal conditions and at 6, 10, and 24 hours after vitamin D intake. Basal 25-hydroxyvitamin D (25-OH-D) levels were significantly lower in blacks (12.5 +/- 2.2 ng/ml (mean +/- SEM)) and in elderly whites (19.2 +/- 1.9 ng/ml), compared with young whites (30.2 +/- 3.0 ng/ml (p < 0.0001)); levels of basal 1,25-dihydroxyvitamin D (1,25(OH)2 -D) did not differ between groups. The vitamin D blood curve was similar between groups after the oral vitamin D2 load. Increases in 25-OH-D were 91.7 +/- 15.9% in blacks, 18.8 +/- 5.2% in young whites, and 28.6 +/- 6.9 in elderly whites; 1,25(OH)2-D levels increased slightly and did not differ between groups, although in blacks the change over time was significant (p < 0.05). As a whole, the study populations exhibited a strong relation between basal and peak 25-OH-D (r = -0.80; p < 0.001). Levels of intact parathyroid hormone and serum calcium of blacks and young whites did not differ within or between groups throughout the test.(ABSTRACT TRUNCATED AT 250 WORDS)