Relative importance of summer sun exposure, vitamin D intake, and genes to vitamin D status in Dutch older adults: The B-PROOF study.
The prevalence of vitamin D deficiency among seniors is high. Whereas sun exposure, vitamin D intake, genes, demographics, and lifestyle have been identified as being important determinants of vitamin D status, the impact of these factors is expected to differ across populations. To improve current prevention and treatment strategies, this study aimed to explore the main determinants of vitamin D status and its relative importance in a population of community-dwelling Dutch older adults.



Serum 25-hydroxyvitamin D (25(OH)D) was measured in 2857 adults aged ≥65 years. Sun exposure was assessed with a structured questionnaire (n=1012), vitamin D intake using a Food Frequency Questionnaire (n=596), and data on genetic variation that may affect 25(OH)D status was obtained for 4 genes, DHCR7 (rs12785878), CYP2R1 (rs10741657), GC (rs2282679), and CYP24A1 (rs6013897) (n=2530).



Serum 25(OH)D concentrations <50nmol/L were observed in 45% of the population; only 6% of these participants used vitamin D supplements. Sun exposure (being outside daily during summer: 66±25nmol/L vs not being outside daily during summer: 58±27nmol/L, P=0.02) and vitamin D intake (per unit μg/day during winter/spring: 3.1±0.75nmol/L, P<0.0001) were associated with higher 25(OH)D concentrations. Major allele carriers of SNPs related to DHCR7, CYP24A1, and GC, as well as CYP2R1 minor allele carriers had the highest 25(OH)D concentrations. Together, sun (R2=0.29), vitamin D intake (R2=0.24), and genes (R2=0.28) explained 35% (R2=0.35) of the variation in 25(OH)D concentrations during summer/autumn period, when adjusted for age, sex, BMI, education, alcohol consumption, smoking, physical activity, and self-rated health status (n=185).



The investigated determinants explained 35% of 25(OH)D status. Of the three main determinants under study, sun exposure still appeared to be an important determinant of serum 25(OH)D in older individuals, closely followed by genes, and vitamin D intake. Given the low frequency of vitamin D supplement use in this population, promoting supplement use may be an inexpensive, easy, and effective strategy to fight vitamin D deficiency.
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands. Electronic address: elske.brouwer-brolsma@wur.nl.
Elske M
EM
Brouwer-Brolsma
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Anouk M M
AMM
Vaes
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Nikita L
NL
van der Zwaluw
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Janneke P
JP
van Wijngaarden
Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
Karin M A
KMA
Swart
Department of Internal Medicine, Erasmus University Medical Centre, P.O. Box 2040, 3000CA Rotterdam, the Netherlands.
Annelies C
AC
Ham
Department of Internal Medicine, Erasmus University Medical Centre, P.O. Box 2040, 3000CA Rotterdam, the Netherlands.
Suzanne C
SC
van Dijk
Department of Internal Medicine, Erasmus University Medical Centre, P.O. Box 2040, 3000CA Rotterdam, the Netherlands.
Anke W
AW
Enneman
Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
Evelien
E
Sohl
Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands.
Natasja M
NM
van Schoor
Department of Internal Medicine, Erasmus University Medical Centre, P.O. Box 2040, 3000CA Rotterdam, the Netherlands; Department of Internal Medicine, Section of Geriatrics, Academic Medical Center, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
Nathalie
N
van der Velde
Department of Internal Medicine, Erasmus University Medical Centre, P.O. Box 2040, 3000CA Rotterdam, the Netherlands.
Andre G
AG
Uitterlinden
Department of Epidemiology and Biostatistics and the EMGO Institute for Health and Care Research, VU University Medical Centre, Van der Boechorststraat 7, 1081 BT Amsterdam, The Netherlands; Department of Internal Medicine, Endocrine Section, VU University Medical Center, P.O.Box 7057, 1007 MB Amsterdam, The Netherlands.
Paul
P
Lips
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Edith J M
EJM
Feskens
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Rosalie A M
RAM
Dhonukshe-Rutten
Division of Human Nutrition, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
Lisette C P G M
LCPGM
de Groot
D000368:Aged; D000369:Aged, 80 and over; D053493:Cholestanetriol 26-Monooxygenase / Q000235:genetics; D003430:Cross-Sectional Studies; D000072467:Cytochrome P450 Family 2 / Q000235:genetics; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D008297:Male; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics; D020641:Polymorphism, Single Nucleotide; D012621:Seasons; D013472:Sunlight; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood / Q000235:genetics / Q000627:therapeutic use*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000235:genetics* / Q000517:prevention & control; D065668:Vitamin D3 24-Hydroxylase / Q000235:genetics; D014815:Vitamins / Q000235:genetics / Q000627:therapeutic use*
D014815:Vitamins; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D000072467:Cytochrome P450 Family 2; C506833:CYP2R1 protein, human; D053493:Cholestanetriol 26-Monooxygenase; D065668:Vitamin D3 24-Hydroxylase; D044925:Oxidoreductases Acting on CH-CH Group Donors; C019995:7-dehydrocholesterol reductase
Serum 25-hydroxyvitamin D; Sunlight; Vitamin D intake; Vitamin D related genetic variation; Vitamin D supplement