Skin Reflectance Research Articles

Association of melanocortin 1 receptor gene (MC1R) polymorphisms with skin reflectance and freckles in Japanese

Most studies on the genetic basis of human skin pigmentation have focused on people of European ancestry and only a few studies have focused on Asian populations. We investigated the association of skin reflectance and freckling with genetic variants of melanocortin 1 receptor (MC1R) gene in Japanese. DNA samples were obtained from a total of 653 Japanese individuals (ages 19-40 years) residing in Okinawa; skin reflectance was measured using a spectrophotometer and freckling status was determined for each individual. Lightness index (L*) and freckling status were not correlated with age, body mass index or ancestry (Ryukyuan or Main Islanders of Japan). Among the 10 nonsynonymous variants that were identified by direct sequencing of the coding region of MC1R, two variants--R163Q and V92M--with the derived allele frequencies of 78.6 and 5.5%, respectively, were most common. Multiple regression analysis showed that the 163Q allele and the presence of nonsynonymous rare variants (allele frequencies <5%) were significantly associated with an increase in sex-standardized skin lightness (L* of CIELAB (CIE 1976 (L*a*b*) color space)) of the inner upper arm. Relative to the 92V allele, the 92M allele was significantly associated with increased odds of freckling. This is the first study to show an association between the 163Q allele and skin reflectance values; this association indicated that light-toned skin may have been subjected to positive selection in East Asian people.

Nonablative fractional laser resurfacing for the treatment of scars and grafts after Mohs micrographic surgery: a randomized controlled trial

Mohs micrographic surgery is a tissue sparing surgical technique for removal of skin cancer. To optimize the cosmetic result of scars and skin grafts after surgery non invasive procedures as non-ablative fractional laser (NAFL) resurfacing are attractive. To evaluate efficacy and safety of 1540 nm NAFL in the treatment of scars and skin grafts after Mohs micrographic surgery. An intra-individual randomized controlled trial (RCT) with split lesion design and single blinded outcome evaluations. Patients receive four treatments at monthly interval with NAFL [StarLux-300 with Lux 1540 nm fractional handpiece (Palomar technologies)]. Primary endpoint to evaluate efficacy is a blinded on site visual and palpable Physician Global Assessment (PhGA). Adverse event and pain registration are used to evaluate safety. Patient's global assessment (PGA) and skin reflectance measurements are secondary endpoints. The PhGA score comparing the treated to the untreated control side of 24 patients is significant different 1 (P = 0.009) and 3 (P = 0.001) months after treatment (Wilcoxon signed rank test). Patients experienced mild to moderate pain. Four days after the treatments patients reported erythema (67%), oedema (31%), crusts (22%), burning sensation (14%), purpura (9%) and vesicles (4%). No long term adverse events are reported. PGA is significant different 1 (P < 0. 001) and 3 months (P < 0. 001) after the last treatment. Skin reflectance do not show significant difference. This study shows that nonablative 1540 nm fractional laser is a safe and effective treatment for the improvement of scars and grafts after Mohs surgery.

Multiple-reflection model of human skin and estimation of pigment concentrations

We describe a new method for estimating the concentrations of pigments in the human skin using surface spectral reflectance. We derive an equation that expresses the surface spectral reflectance of the human skin. First, we propose an optical model of the human skin that accounts for the stratum corneum. We also consider the difference between the scattering coefficient of the epidermis and that of the dermis. We then derive an equation by applying the Kubelka-Munk theory to an optical model of the human skin. Unlike a model developed in a recent study, the present equation considers pigments as well as multiple reflections and the thicknesses of the skin layers as factors that affect the color of the human skin. In two experiments, we estimate the pigment concentrations using the measured surface spectral reflectances. Finally, we confirm the feasibility of the concentrations estimated by the proposed method by evaluating the estimated pigment concentrations in the skin.

A portable system for noninvasive assessment of advanced glycation end-products using skin fluorescence and reflectance spectrum

An optical system has been developed for noninvasive assessment of skin advanced glycation end-products (AGEs). The system comprises mainly a high-power ultraviolet light emitting diode (LED) as an excitation source, an LED array for the reflectance measurement, a trifurcated fiber-optic probe for light transmitting and receiving, and a compact spectrometer for light detecting. Both skin fluorescence of a subject and the reflectance spectrum of the same site can be obtained in a single measurement with the system. Demonstrative measurements with the system have been conducted. Results indicate that the measured reflectance spectrum can be used to compensate for the distortion of AGEs fluorescence, which is caused by skin absorption and scattering. The system is noninvasive, portable, easy to operate, and has potential applications for clinical diagnosis of AGE-related diseases, especially diabetes mellitus.

Quantitative skin color measurements in acanthosis nigricans patients: colorimetry and diffuse reflectance spectroscopy

Tristimulus colorimetry and diffuse reflectance spectroscopy (DRS) are white-light skin reflectance techniques used to measure the intensity of skin pigmentation. The tristimulus colorimeter is an instrument that measures a perceived color and the DRS instrument measures biological chromophores of the skin, including oxy- and deoxyhemoglobin, melanin and scattering. Data gathered from these tools can be used to understand morphological changes induced in skin chromophores due to conditions of the skin or their treatments. The purpose of this study was to evaluate the use of these two instruments in color measurements of acanthosis nigricans (AN) lesions. Eight patients with hyperinsulinemia and clinically diagnosable AN were seen monthly. Skin pigmentation was measured at three sites: the inner forearm, the medial aspect of the posterior neck, and anterior neck unaffected by AN. Of the three, measured tristimulus L*a*b* color parameters, the luminosity parameter L* was found to most reliably distinguish lesion from normally pigmented skin. The DRS instrument was able to characterize a lesion on the basis of the calculated melanin concentration, though melanin is a weak indicator of skin change and not a reliable measure to be used independently. Calculated oxyhemoglobin and deoxyhemoglobin concentrations were not found to be reliable indicators of AN. Tristimulus colorimetry may provide reliable methods for respectively quantifying and characterizing the objective color change in AN, while DRS may be useful in characterizing changes in skin melanin content associated with this skin condition.

Global behavioral variation: A test of differential-K

Despite Rushton’s path-breaking work into evolutionary forces affecting life history traits, not many attempts at operationalizing the differential-K spectrum at the level of countries or racial groups have been made so far. We report the construction of a “national K” factor from country-level behavioral variables. This K factor is closely related to country-level intelligence (“g”), operationalized by a composite score of IQ and scholastic achievement. We further demonstrate relationships of both g and K with measures of current environment and hypothesized evolutionary antecedents. Whereas K is predicted most powerfully by intelligence, log-transformed GDP (lgGDP) and skin reflectance, g is predicted by skin reflectance, lgGDP, cranial capacity, and a measure of evolutionary novelty.

Vitamin D Assessment Using Simple Questionnaires from a College Cohort Study

Vitamin D is important to the health of college students. Our objective was to measure vitamin D intake, sun exposure, skin pigmentation, and serum 25‐hydroxyvitamin D (25[OH]D) in a subset of students from the FLASH Longitudinal College Health Study at Cal Poly, San Luis Obispo, CA. Vitamin D intake and sun exposure were measured using two different tools. First, an online categorical (C) questionnaire administered by the FLASH Study including fish and milk intake, minutes in the sun on the weekdays and weekends. Second, a 28 day recall (R) questionnaire specific to vitamin D foods/supplements, and sun exposure with minutes outside and clothing worn to calculate a sun exposure index (SEI). Skin pigmentation was measured using a reflectance spectrophotometer. Serum 25(OH)D was measured at a local pathology lab. The different measurements for diet and sun exposure were each incorporated into a regression model along with average forehead skin reflectance (FSR) to predict 25(OH)D (Spring 2010, n=35). The average SEI from 11am–3pm (R), fish intake (C), and FSR were significant predictors (R2=0.39, p=0.0036). Weekend sun exposure (C), average monthly intake of vitamin D (R) and FSR were also significant predictors (R2=0.42, p=0.0005). Weekend sun exposure (C), fish intake (C), and FSR were the strongest predictors (R2=0.50, p=0.0001). Thus, simple questionnaires can be used to help determine vitamin D status.

Poster #215 COMPARISON OF OUTCOMES IN PATIENTS WITH EARLY PHASE VERSUS LATER PHASE SCHIZOPHRENIA

The heart rate of subjects is extracted from video data during exercises and is treated as a negative feedback parameter for the control of fitness devices. The probability distribution in RGB space of the parameters of the skin reflection model is analyzed based on the experimental data taken under a wide range of environmental settings. A novel pulse extraction algorithm is proposed based on this distribution, which sets aside distribution centers as the model parameters for preliminary pulse separation and adopts cascade least mean square adaptive filters to compensate for modeling errors. A Gaussian distribution-based heart rate estimation algorithm is employed for heart rate stabilization. In addition, the concept of heart rate negative feedback control is introduced, e.g., the treadmill speed and incline can be adjusted interactively based on the subject's heart rate. The heart rate measurement accuracy and the control scheme have been evaluated by a self-collected benchmark dataset and a prototype system. The heart rate measurement accuracy is increased over the state-of-the-art algorithms by more than 10% on average. The heart rate negative feedback control improves human–machine interaction performance compared with a traditional control scheme that uses the predefined program regardless of the subjects’ physical state. The proposed technique pioneers new possibilities for the usage of fitness devices.

You Are What You Eat: Within-Subject Increases in Fruit and Vegetable Consumption Confer Beneficial Skin-Color Changes

BackgroundFruit and vegetable consumption and ingestion of carotenoids have been found to be associated with human skin-color (yellowness) in a recent cross-sectional study. This carotenoid-based coloration contributes beneficially to the appearance of health in humans and is held to be a sexually selected cue of condition in other species.Methodology and Principal FindingsHere we investigate the effects of fruit and vegetable consumption on skin-color longitudinally to determine the magnitude and duration of diet change required to change skin-color perceptibly. Diet and skin-color were recorded at baseline and after three and six weeks, in a group of 35 individuals who were without makeup, self-tanning agents and/or recent intensive UV exposure. Six-week changes in fruit and vegetable consumption were significantly correlated with changes in skin redness and yellowness over this period, and diet-linked skin reflectance changes were significantly associated with the spectral absorption of carotenoids and not melanin. We also used psychophysical methods to investigate the minimum color change required to confer perceptibly healthier and more attractive skin-coloration. Modest dietary changes are required to enhance apparent health (2.91 portions per day) and attractiveness (3.30 portions).ConclusionsIncreased fruit and vegetable consumption confers measurable and perceptibly beneficial effects on Caucasian skin appearance within six weeks. This effect could potentially be used as a motivational tool in dietary intervention.

Reflectance spectrometry of normal and bruised human skins: experiments and modeling

A stochastic photon transport model in multilayer skin tissue combined with reflectance spectroscopy measurements is used to study normal and bruised skins. The model is shown to provide a very good approximation to both normal and bruised real skin tissues by comparing experimental and simulated reflectance spectra. The sensitivity analysis of the skin reflectance spectrum to variations of skin layer thicknesses, blood oxygenation parameter and concentrations of main chromophores is performed to optimize model parameters. The reflectance spectrum of a developed bruise in a healthy adult is simulated, and the concentrations of bilirubin, blood volume fraction and blood oxygenation parameter are determined for different times as the bruise progresses. It is shown that bilirubin and blood volume fraction reach their peak values at 80 and 55 h after contusion, respectively, and the oxygenation parameter is lower than its normal value during 80 h after contusion occurred. The obtained time correlations of chromophore concentrations in developing contusions are shown to be consistent with previous studies. The developed model uses a detailed seven-layer skin approximation for contusion and allows one to obtain more biologically relevant results than those obtained with previous models using one- to three-layer skin approximations. A combination of modeling with spectroscopy measurements provides a new tool for detailed biomedical studies of human skin tissue and for age determination of contusions.

Circumcision in Nesbit Corporoplasty: A Mandatory Time? Our Experience on 158 Patients

The Nesbit procedure is the most common surgical technique to correct congenital or acquired penile curvature. It is a common opinion that this surgical procedure has to be completed with a circumcision to prevent foreskin necrosis or phimosis. According to our experience we believe that some procedural "tricks" could strongly reduce that mechanical and ischemic trauma on the foreskin responsible for these complications. From 1988 to 2010 we selected 158 patients treated with Nesbit's corporoplasty. The procedure was recommended to patients who presented a penile curvature wider than 30° and reporting however some difficulty or pain at coitus, or to patients who complained about aesthetical problems (123 patients presented a La Peyronie disease and 35 presented a congenital curvature). Eleven patients underwent circumcision during surgery because of a pre-operative phimosis, or according to their own desire. Among the patients who did not undergo circumcision (147), paraphimosis was present in 3 patients. We reported only one case of curvature recurrence in a patient who had a sexual intercourse the day after surgery. We also had one case of hourglass effect in a congenital curvature. We believe that some tricks during Nesbit surgical procedure could prevent tissue and vascular trauma that give rise to tissue retraction, and consequently to phimosis and foreskin necrosis: a coronal incision to 0.5-1cm from the gland line would allow to let intact an adequate amount of reflection of skin (prepuce) bound of preputial skin reflection , maintaining good vascularity. The careful degloving with preparatory isolation of the dissection plan between dartos and Buck's fascia, can reduce vascular trauma of the fascia, minimizing bleeding and ensuring tissue vitality. Moreover, execution of only two hydraulics erections, after degloving and after correction, causes a minimal tissue stress. Circumcision must not be considered a mandatory time in Nesbit procedure: on the contrary, mandatory is the respect of the anatomical structures surgically attacked to avoid preputial resection.

Smoltification in an Impounded, Adfluvial Redband Trout Population Upstream from an Impassable Dam: Does It Persist?

AbstractThis study evaluated whether a population of adfluvial redband trout Oncorhynchus mykiss gairdnerii (a subspecies of rainbow trout) in Mann Creek and Reservoir, southwestern Idaho, continues to undergo smoltification. This population had an anadromous component before the construction of main‐stem and tributary dams in 1958 and 1967, respectively. Smoltification was assessed by quantifying the proportion of juvenile migrants that displayed high skin reflectance, comparing mean gill Na+,K+‐ATPase activity among migrants, and examining migration timing compared with that of neighboring steelhead (anadromous rainbow trout) populations. Approximately one‐quarter of the 1,502 juvenile migrants trapped and examined displayed the intermediate or high skin reflectance (nonbanded silvery coloration) characteristic of smolts; the other fish maintained a banded coloration more typical of resident fish. For 78 samples of gill filaments over the course of the migration season (18 March to 3 June), Na+,K+‐ATPase activity varied considerably among fish (0.95–5.81 μmol Pi · h−1 · mg protein−1) and doubled in nonbanded fish over the course of the migration period. ATPase activity was significantly higher for nonbanded fish than for banded fish at the end of the migration period (21 May – 4 June). Juvenile adfluvial redband trout migrated from Mann Creek in approximate synchrony with neighboring steelhead populations. These results suggest the possibility that in areas in the Snake River drainage where steelhead have been extirpated as a result of artificial barriers, remnant populations retain the potential for anadromy.

Genetic ancestry, skin reflectance and pigmentation genotypes in association with serum vitamin D metabolite balance

Lower serum vitamin D (25(OH)D) among individuals with African ancestry is attributed primarily to skin pigmentation. However, the influence of genetic polymorphisms controlling for skin melanin content has not been investigated. Therefore, we investigated differences in non-summer serum vitamin D metabolites according to self-reported race, genetic ancestry, skin reflectance and key pigmentation genes (SLC45A2 and SLC24A5). Healthy individuals reporting at least half African American or half European American heritage were frequency matched to one another on age (+/- 2 years) and sex. 176 autosomal ancestry informative markers were used to estimate genetic ancestry. Melanin index was measured by reflectance spectrometry. Serum vitamin D metabolites (25(OH)D3, 25(OH)D 2 and 24,25(OH)2D3) were determined by high performance liquid chromatography (HPLC) tandem mass spectrometry. Percent 24,25(OH)2D3 was calculated as a percent of the parent metabolite (25(OH)D3). Stepwise and backward selection regression models were used to identify leading covariates. Fifty African Americans and 50 European Americans participated in the study. Compared with SLC24A5 111Thr homozygotes, individuals with the SLC24A5 111Thr/Ala and 111Ala/Ala genotypes had respectively lower levels of 25(OH)D3 (23.0 and 23.8 nmol/L lower, p-dominant=0.007), and percent 24,25(OH)2D3 (4.1 and 5.2 percent lower, p-dominant=0.003), controlling for tanning bed use, vitamin D/fish oil supplement intake, race/ethnicity, and genetic ancestry. Results were similar with melanin index adjustment, and were not confounded by glucocorticoid, oral contraceptive, or statin use. The SLC24A5 111Ala allele was associated with lower serum vitamin 25(OH)D3 and lower percent 24,25(OH)2D3, independently from melanin index and West African genetic ancestry.

Reference values for the Chinese population of skin autofluorescence as a marker of advanced glycation end products accumulated in tissue

Advanced glycation end products play an important role in the pathophysiology of several chronic and age-related diseases, especially diabetes mellitus. Skin autofluorescence is a non-invasive method for assessing levels of tissue advanced glycation end products. This study aims to establish the normal reference value of advanced glycation end products accumulated in tissue measured by the advanced glycation end product reader--skin autofluorescence--and discusses some factors influencing it. The values of autofluorescence in healthy individuals in China were determined by the advanced glycation end product reader; age, gender, skin reflectance, smoking habits and alcohol consumption of the subjects were also recorded. The mean reference values of autofluorescence in healthy Chinese subjects are (95% confidence interval) 20-29 years: 1.54-1.62 arbitrary units; 30-39 years: 1.66-1.75; 40-49 years: 1.78-1.89; 50-59 years: 1.87-2.03; 60-69 years: 1.86-2.09; 70-79 years: 1.97-2.31. The value of autofluorescence is strongly related to age, but no significant difference between males and females were found (all P > 0.05). Autofluorescence was higher in smokers than in non-smokers (P < 0.05). In persons with low skin reflectance (< 10%), skin autofluorescence was dependent on skin colour, but was still related to age. The mean reference values of autofluorescence we established could be used for a Chinese population in a clinical setting and are agreement with those in a Caucasian population. Future developments are needed to make the advanced glycation end product reader reliable for lower skin reflections as well, independently of the skin colour.

Occupational Exposures to Solar Ultraviolet Radiation of Vineyard Workers in Tuscany (Italy)

A study to quantify the UV exposure of vineyard workers was carried out using polysulphone dosimetry. The study took place in Tuscany (Italy) involving 32 vineyard workers, covering three different stages of the vine's growth. The level of personal exposure expressed as a function on the available ambient UV radiation was determined. We also assessed skin reflectance parameters, pre and post exposure. It was found that during spring backs received between 53% and 87% of ambient exposure and arms between 30% and 60%. During summer, the workers received on the back between 36% and 77% of ambient exposure and between 19% and 43% of ambient exposure on the arm. The comparison with the occupational UV exposure limit showed that all subjects received UV exposures in excess of the limit. The exposure of back of neck exceeded 10 SED (assumed as a threshold level of sun-adapted skin for Mediterranean subjects) in spring, which means that in the case of non sun-adapted skin and without sun protection, erythema can be induced in this targeted population. The cumulative exposure was also estimated under specific assumptions of UV exposure giving values in some cases higher than previous studies.

SU‐E‐T‐34: Time Series Analysis of Skin Reactions during Heck and Neck IMRT

Purpose: To quantitatively characterize the time sequence of skin erythema in head and neck patients undergoing intensity modulated radiation therapy (IMRT) treatments using optical reflectance spectroscopy. The overall goal is to identify patients who will develop extreme skin responses earlier than is possible by visual inspection alone. Methods: Ten (10) patients undergoing IMRT for the treatment of head and neck cancers were followed throughout the course of their intervention. Daily spectral skin reflectance measurements were made in order to track changes in the tissue optical properties. Weekly thermoluminescent detector (TLD) readings were performed in the measurement area to verify the dose calculated by the treatment planning system. Patients also completed a weekly questionnaire on factors that may have affected their skin reaction, and were visually inspected by a radiation oncologist.Results: The data were fit by a 2‐component principle component analysis (PCA) model. The preliminary results show that absorbed dose is the largest contributor to changes in the spectral reflectance and that those changes are seen primarily at wavelengths above 600 nm. Differences among patient skin responses were seen and accounted for in the model Conclusions: The PCA model indicates that it may be possible to predict a patientˈs spectral skin reflectance measurement on the final day of treatment given an initial spectrum and the dose. Therefore, further analysis of the data may yield a method of determining patient reactions before visible signs are detected.Partial funding through Varian, Inc. and the Natural Sciences and Engineering Research Council of Canada.

Wide Disparity in Genetic Admixture Among Mexican Americans from San Antonio, TX

We studied 706 participants of the San Antonio Family Diabetes Study (SAFDS) and 586 male samples from the San Antonio Center for Biomarkers of Risk of Prostate Cancer (SABOR) and used 64 ancestry informative markers to compare admixture proportions between both groups. Existence of population substructure was demonstrated by the excess association of unlinked markers. In the SAFDS sample, ancestral proportions were estimated at 50.2 ± 0.6% European, 46.4 ± 0.6% Native American, and 3.1 ± 0.2% West African. For the SABOR sample, the proportions were 58.9 ± 0.7%, 38.2 ± 0.7%, and 2.9 ± 0.2%, respectively. Additionally, in the SAFDS subjects a highly significant negative correlation was found between individual Native American ancestry and skin reflectance (R(2) = 0.07, P= 0.00006). The correlation was stronger in males than in females but clearly showed that ancestry only accounts for a small percentage of the variation in skin color and, conversely, that skin reflectance is not a robust surrogate for genetic admixture. Furthermore, a substantial difference in substructure is present in the two cohorts of Mexican American subjects from the San Antonio area in Texas, which emphasizes that genetic admixture estimates should be accounted for in association studies, even for geographically related subjects.

Efficacy of 694-nm Q-Switched Ruby Fractional Laser Treatment of Melasma in Female Korean Patients

Melasma is a common acquired symmetrical hypermelanosis of sun-exposed areas of the skin. Although the classical Q-switched ruby laser (QSRL) has been used successfully for the removal of tattoos and for the treatment of cutaneous pigmented lesions, its efficacy for melasma remains controversial. We used repeat low-dose fractional QSRL treatment for melasma and analyzed the clinical results. Fifteen Korean women with melasma were enrolled. Each patient received six low-dose fractional QSRL treatments to the face at 2-week intervals. Two investigators independently evaluated Melasma Area and Severity Index (MASI) scores before each session and 4 and 16 weeks after the final session. The intensities of pigmentation and erythema were assessed by measuring skin reflectance using a tristimulus color analyzer. Mean MASI score decreased from 15.1 ± 3.3 before treatment to 10.6 ± 3.9 16 weeks after the final treatment. The lightness of pigmentation (L-value) increased from 56.6 ± 3.5 before treatment to 59.9 ± 2.8 16 weeks after the final treatment. Multiple treatment sessions of low-dose fractional QSRL may be an effective strategy for the treatment of dermal or mixed-type melasma.

Specific features of diffuse reflection of human face skin for laser and non-laser sources of visible and near-IR light

The specific features of diffuse reflection from different areas of human face skin for laser and non-laser sources of visible and near-IR light have been investigated to localise the closed-eye (eyelid) region. In the visible spectral range the reflection from the eyelid skin surface can be differentiated by measuring the slope of the spectral dependence of the effective optical density of skin in the wavelength range from 650 to 700nm. In the near-IR spectral range the reflectances of the skin surface at certain wavelengths, normalised to the forehead skin reflectance, can be used as a criterion for differentiating the eyelid skin. In this case, a maximum discrimination is obtained when measuring the skin reflectances at laser wavelengths of 1310 and 1470nm, which correspond to the spectral ranges of maximum and minimum water absorption.

Tanning predicts bone mass but not structure in adolescent females living in Hawaii

To evaluate the relationship between facultative skin pigmentation, which predicts circulating levels of plasma 25-hydroxymitamin D, and several measures of bone mass and structure in a cross sectional sample of adolescent females living in Hawaii. Our sample was composed of adolescent females (n = 94) living in Hawaii where seasonal sun exposure is minimal, and who self-identified as either white (n = 16) or Asian (n = 78). Bone mineral content (BMC) of the total body, the lumbar spine and the hip, and cross sectional area (CSA) and section modulus (Z) at the proximal femur were quantified using DXA. Facultative skin pigmentation was measured at the forehead and non-facultative skin pigmentation was measured at the inner arm using a Chroma Meter CR-200b colorimeter. There were no significant differences between ethnic groups in terms of skin pigmentation. The difference between a* taken at the forehead and inner upper arm significantly predicted BMC at the lumbar spine, total hip, and total body. Other measures of skin pigmentation were not significant predictors of any other measure of skeletal integrity. The difference between facultative and non-facultative skin pigmentation for a* is a significant predictor BMC, but not bone structure. Our findings are limited by an inability to control for long term UVA and UVB exposure and lack of a measure of serum 25(OH)D status. Further research is needed to examine these questions, particularly in populations who live at high latitudes where a winter season limits vitamin D(3) synthesis.