Journal of Photochemistry and Photobiology B: Biology 145 (2015) 25–29
Contents lists available at ScienceDirect
Journal of Photochemistry and Photobiology B: Biology journal homepage: www.elsevier.com/locate/jphotobiol
Evaluation of fall Sun Exposure Score in predicting vitamin D status in young Canadian adults, and the influence of ancestry Lauren Sham a, E. Ann Yeh a,b, Sandra Magalhaes c, Esteban J. Parra d, Agnes Gozdzik d, Brenda Banwell a,e, Heather E. Hanwell a,⇑ a
Neurosciences and Mental Health Program, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Department of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada d Department of Anthropology, University of Toronto at Mississauga, Mississauga, Ontario, Canada e Department of Neurology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA b c
a r t i c l e
i n f o
Article history: Received 8 October 2014 Received in revised form 19 January 2015 Accepted 5 February 2015 Available online 16 February 2015
a b s t r a c t Query of sun-related habits or ancestry could help screen for risk of vitamin D insufficiency (serum 25-hydroxyvitamin D < 75 nmol/L). We evaluated the association between Sun Exposure Score (calculated from recall of Time Exposed to Sun and Skin Exposed to Sun in the previous week), demographics and anthropometrics (including self-reported ancestry and skin melanin reflectometry), and serum 25(OH)D levels in healthy young Canadian adults in the Greater Toronto Area (GTA; 43°N) during fall. 310 adults (67% female) of European, East Asian, and South Asian ancestries were evaluated. The median (interquartile range) 25(OH)D level was 49.7 nmol/L (36.7–70.3) and 80% of participants were vitamin D insufficient. The vast majority of those of East and South Asian ancestry were vitamin D insufficient (91% and 97%, respectively), as were 55% of those of European ancestry. Sun Exposure Score and 25(OH)D concentrations were not associated after accounting for confounders. A multivariable model showed ancestry, recent summer sun exposure, sex, melanin, vitamin D intake, age and year of study significantly predicted 25(OH)D concentration; ancestry was the strongest independent predictor (adjusted R2 = 43%). Although Sun Exposure Score was not a significant predictor of serum 25(OH)D levels, inquiry of ancestry has potential use in screening for vitamin D insufficiency. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction Vitamin D insufficiency is associated with increased risk of and poorer outcomes in autoimmune, cardiovascular and malignant disease. Although vitamin D can be obtained through diet or supplements, our main source is solar ultraviolet (UV)-B mediated cutaneous synthesis. In Canada, seasonal fluctuations in solar UVB and, thus, resultant production of vitamin D limit the utility of serum 25-hydroxyvitamin D [25(OH)D] tests [1]. A brief questionnaire to screen sun exposure could provide a cost and time-effective strategy to guide individual vitamin D supplementation practices.
In a previous study of healthy Italian adults, a 7-day sun exposure questionnaire predicted serum 25(OH)D concentrations in the summer [2]. However, the utility of this questionnaire in estimating vitamin D status in other settings is unknown. We therefore sought to evaluate the value of the Sun Exposure Score in predicting fall 25(OH)D concentrations in ancestrally diverse young Canadian adults, and to ascertain the strongest predictors of 25(OH)D concentrations, including sun exposure, self-reported ancestry, skin pigmentation and vitamin D intake. 2. Materials and methods 2.1. Study population and recruitment
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; BMI, body mass index; FFQ, food frequency questionnaire; IQR, inter-quartile range; IU, international units; n, number; SD, standard deviation; y, years. ⇑ Corresponding author at: Pediatric Demyelinating Disease Program, The Hospital for Sick Children, 686 Bay St Rm 8.9840, Toronto, Ontario M5G 0A4, Canada. Tel.: +1 416 813 7654x328574; fax: +1 416 813 5140. E-mail address: [email protected] (H.E. Hanwell). http://dx.doi.org/10.1016/j.jphotobiol.2015.02.007 1011-1344/Ó 2015 Elsevier B.V. All rights reserved.
Recruitment, study eligibility and most aspects of data collection have been previously described [1]. Participants between the ages of 18 and 35 years were recruited at the University of Toronto Mississauga campus (Toronto, Ontario, Canada; 43°N) in fall 2007 and 2008. Exclusion criteria included
26
L. Sham et al. / Journal of Photochemistry and Photobiology B: Biology 145 (2015) 25–29
kidney or liver disease, a diagnosis potentially affecting vitamin D metabolism or absorption, such as osteomalacia, osteopenia, or Crohn’s disease, use of medications affecting vitamin D metabolism such as steroids or anticonvulsants, and recent exposure to unseasonably high UVB (e.g. tanning salons or travel to sunny destinations in the preceding three months). This study was approved by the University of Toronto Health Sciences Research Ethics Board, and all participants provided written informed consent. 2.2. Data collection Participants completed a visit during September–October of 2007 or 2008. Information on age, sex, weight, height, ancestry, and sun exposure (summer and fall) was collected, as described below. A blood sample was drawn for determination of 25(OH)D concentration. Constitutive skin pigmentation (melanin) was derived from the mean of three measures taken using a narrowband reflectometer (Dermaspectrometer, Cortex Technology) at the upper inner arm (previously validated as a method of objective determination of melanin levels in human skin [3]). 2.2.1. Sun Exposure Score Participants completed a sun exposure questionnaire based on Time Exposed to Sun (0 = 6 5 min., 1 = 5–30 min., and 2 = P 30 min.) and Skin Exposed to Sun (1 = face and hands uncovered, 2 = arms uncovered, 3 = legs uncovered, 4 = ‘‘bathing suit’’) for each day in the previous week (Fig. 1). This questionnaire was previously validated in a population of middle-aged healthy Italian adults during the summer [2]. A daily Sun Exposure Score was calculated based on the product of the Time Exposed to Sun and Skin Exposed to Sun scores (min = 0, max = 8), and a weekly Sun Exposure Score was calculated by the sum of each day’s exposure scores, as previously described [2]. A minimum score of 0 corresponded to 30 min in bathing suit outdoors in the sun for 7 days a week. 2.2.2. Biochemical analyses Serum 25(OH)D concentration was measured using liquid chromatography tandem mass spectrometry as described previously [1]. 2.2.3. Ancestry A questionnaire was administered, in which participants provided their country of birth, ethnic background, native language (and other languages), and family history (country of birth, native language and ethnic background of their parents and grandparents). Participant ancestry was defined by familial geographic origins: African, East Asian, European, Middle Eastern, South Asian, and Other⁄ (⁄family members from multiple geographic origins).
Day
Mon Tues Wed Thurs Fri Sat Sun
Time Exposed to Sun 30 min 0 0 0 0 0 0 0
1 1 1 1 1 1 1
2 2 2 2 2 2 2
Only those of East Asian, European and South Asian ancestries were included in the present study due to low enrollment of other ancestral groups. 2.2.4. Vitamin D Intake A food frequency questionnaire (FFQ) was used to estimate daily vitamin D intake over the previous month [1,4]. 2.2.5. Recent summer sun exposure Participants estimated the amount of time spent outdoors daily during the most recent summer between 9 a.m. and 5 p.m. (
Contents lists available at ScienceDirect
Journal of Photochemistry and Photobiology B: Biology journal homepage: www.elsevier.com/locate/jphotobiol
Evaluation of fall Sun Exposure Score in predicting vitamin D status in young Canadian adults, and the influence of ancestry Lauren Sham a, E. Ann Yeh a,b, Sandra Magalhaes c, Esteban J. Parra d, Agnes Gozdzik d, Brenda Banwell a,e, Heather E. Hanwell a,⇑ a
Neurosciences and Mental Health Program, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Department of Neurology, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montreal, Quebec, Canada d Department of Anthropology, University of Toronto at Mississauga, Mississauga, Ontario, Canada e Department of Neurology, Children’s Hospital of Philadelphia, University of Pennsylvania, Philadelphia, PA, USA b c
a r t i c l e
i n f o
Article history: Received 8 October 2014 Received in revised form 19 January 2015 Accepted 5 February 2015 Available online 16 February 2015
a b s t r a c t Query of sun-related habits or ancestry could help screen for risk of vitamin D insufficiency (serum 25-hydroxyvitamin D < 75 nmol/L). We evaluated the association between Sun Exposure Score (calculated from recall of Time Exposed to Sun and Skin Exposed to Sun in the previous week), demographics and anthropometrics (including self-reported ancestry and skin melanin reflectometry), and serum 25(OH)D levels in healthy young Canadian adults in the Greater Toronto Area (GTA; 43°N) during fall. 310 adults (67% female) of European, East Asian, and South Asian ancestries were evaluated. The median (interquartile range) 25(OH)D level was 49.7 nmol/L (36.7–70.3) and 80% of participants were vitamin D insufficient. The vast majority of those of East and South Asian ancestry were vitamin D insufficient (91% and 97%, respectively), as were 55% of those of European ancestry. Sun Exposure Score and 25(OH)D concentrations were not associated after accounting for confounders. A multivariable model showed ancestry, recent summer sun exposure, sex, melanin, vitamin D intake, age and year of study significantly predicted 25(OH)D concentration; ancestry was the strongest independent predictor (adjusted R2 = 43%). Although Sun Exposure Score was not a significant predictor of serum 25(OH)D levels, inquiry of ancestry has potential use in screening for vitamin D insufficiency. Ó 2015 Elsevier B.V. All rights reserved.
1. Introduction Vitamin D insufficiency is associated with increased risk of and poorer outcomes in autoimmune, cardiovascular and malignant disease. Although vitamin D can be obtained through diet or supplements, our main source is solar ultraviolet (UV)-B mediated cutaneous synthesis. In Canada, seasonal fluctuations in solar UVB and, thus, resultant production of vitamin D limit the utility of serum 25-hydroxyvitamin D [25(OH)D] tests [1]. A brief questionnaire to screen sun exposure could provide a cost and time-effective strategy to guide individual vitamin D supplementation practices.
In a previous study of healthy Italian adults, a 7-day sun exposure questionnaire predicted serum 25(OH)D concentrations in the summer [2]. However, the utility of this questionnaire in estimating vitamin D status in other settings is unknown. We therefore sought to evaluate the value of the Sun Exposure Score in predicting fall 25(OH)D concentrations in ancestrally diverse young Canadian adults, and to ascertain the strongest predictors of 25(OH)D concentrations, including sun exposure, self-reported ancestry, skin pigmentation and vitamin D intake. 2. Materials and methods 2.1. Study population and recruitment
Abbreviations: 25(OH)D, 25-hydroxyvitamin D; BMI, body mass index; FFQ, food frequency questionnaire; IQR, inter-quartile range; IU, international units; n, number; SD, standard deviation; y, years. ⇑ Corresponding author at: Pediatric Demyelinating Disease Program, The Hospital for Sick Children, 686 Bay St Rm 8.9840, Toronto, Ontario M5G 0A4, Canada. Tel.: +1 416 813 7654x328574; fax: +1 416 813 5140. E-mail address: [email protected] (H.E. Hanwell). http://dx.doi.org/10.1016/j.jphotobiol.2015.02.007 1011-1344/Ó 2015 Elsevier B.V. All rights reserved.
Recruitment, study eligibility and most aspects of data collection have been previously described [1]. Participants between the ages of 18 and 35 years were recruited at the University of Toronto Mississauga campus (Toronto, Ontario, Canada; 43°N) in fall 2007 and 2008. Exclusion criteria included
26
L. Sham et al. / Journal of Photochemistry and Photobiology B: Biology 145 (2015) 25–29
kidney or liver disease, a diagnosis potentially affecting vitamin D metabolism or absorption, such as osteomalacia, osteopenia, or Crohn’s disease, use of medications affecting vitamin D metabolism such as steroids or anticonvulsants, and recent exposure to unseasonably high UVB (e.g. tanning salons or travel to sunny destinations in the preceding three months). This study was approved by the University of Toronto Health Sciences Research Ethics Board, and all participants provided written informed consent. 2.2. Data collection Participants completed a visit during September–October of 2007 or 2008. Information on age, sex, weight, height, ancestry, and sun exposure (summer and fall) was collected, as described below. A blood sample was drawn for determination of 25(OH)D concentration. Constitutive skin pigmentation (melanin) was derived from the mean of three measures taken using a narrowband reflectometer (Dermaspectrometer, Cortex Technology) at the upper inner arm (previously validated as a method of objective determination of melanin levels in human skin [3]). 2.2.1. Sun Exposure Score Participants completed a sun exposure questionnaire based on Time Exposed to Sun (0 = 6 5 min., 1 = 5–30 min., and 2 = P 30 min.) and Skin Exposed to Sun (1 = face and hands uncovered, 2 = arms uncovered, 3 = legs uncovered, 4 = ‘‘bathing suit’’) for each day in the previous week (Fig. 1). This questionnaire was previously validated in a population of middle-aged healthy Italian adults during the summer [2]. A daily Sun Exposure Score was calculated based on the product of the Time Exposed to Sun and Skin Exposed to Sun scores (min = 0, max = 8), and a weekly Sun Exposure Score was calculated by the sum of each day’s exposure scores, as previously described [2]. A minimum score of 0 corresponded to 30 min in bathing suit outdoors in the sun for 7 days a week. 2.2.2. Biochemical analyses Serum 25(OH)D concentration was measured using liquid chromatography tandem mass spectrometry as described previously [1]. 2.2.3. Ancestry A questionnaire was administered, in which participants provided their country of birth, ethnic background, native language (and other languages), and family history (country of birth, native language and ethnic background of their parents and grandparents). Participant ancestry was defined by familial geographic origins: African, East Asian, European, Middle Eastern, South Asian, and Other⁄ (⁄family members from multiple geographic origins).
Day
Mon Tues Wed Thurs Fri Sat Sun
Time Exposed to Sun 30 min 0 0 0 0 0 0 0
1 1 1 1 1 1 1
2 2 2 2 2 2 2
Only those of East Asian, European and South Asian ancestries were included in the present study due to low enrollment of other ancestral groups. 2.2.4. Vitamin D Intake A food frequency questionnaire (FFQ) was used to estimate daily vitamin D intake over the previous month [1,4]. 2.2.5. Recent summer sun exposure Participants estimated the amount of time spent outdoors daily during the most recent summer between 9 a.m. and 5 p.m. (
