Background: Vitamin D may have beneficial effects on cardiometabolic disease, but the evidence is equivocal. This may be due to unaccounted confounders, such as lifestyle factors and genetic variation. We examined the association between circulating 25-hydroxyvitamin D [25(OH)D] and biomarkers of cardiometabolic disease risk, including biomarkers of inflammation, glycemic dysregulation and lipid metabolism, and a panel of 54 plasma proteomic biomarkers, and determined whether lifestyle variables and genetic variation modified these associations.
Methods: Participants were from the Toronto Nutrigenomics and Health Study, an ethnically diverse population of individuals aged 20-29 years. Anthropometric measurements were obtained. Participants answered general health and lifestyle and food frequency questionnaires and provided a fasting blood sample for biochemical measurements and genotyping.
Results: Across ethnic groups, women who used hormonal contraceptives (HC) had higher 25(OH)D and C-reactive protein (CRP) than women HC non-users and men. Circulating 25(OH)D was positively associated with CRP in the entire population in models not accounting for HC use. However, there was no association after accounting for HC use. 25(OH)D was also not associated with inflammatory cytokines after adjusting for HC use. 25(OH)D was inversely associated with insulin, HOMA-IR, and HOMA-Beta among Caucasians and East Asians and among men and women HC non-users. No biomarkers were associated with 25(OH)D among South Asians and women HC users, although non-significant inverse trends were observed for markers of glycemic dysregulation. Only two of the 54 plasma proteomic biomarkers were associated with 25(OH)D in women HC non-users, and none were associated in men. Among women HC users, after accounting for hormone dose, only three proteins were associated with 25(OH)D. Finally, 25(OH)D affected the association between rs2239182, a variant in the vitamin D receptor (VDR) and the pro-inflammatory cytokine interferon gamma-induced protein 10 (IP-10). However, the association was suggestive of heterosis and may have been due to chance.
Conclusions: We identified a confounding effect of HC use on the association between 25(OH)D, biomarkers of inflammation and plasma proteomic biomarkers. In addition, HC use might also affect the association between 25(OH)D and biomarkers of glycemic dysregulation. Genetic variation in VDR did not modify any associations.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:OTU.1807/43564 |
| Date | 09 January 2014 |
| Creators | Garcia Bailo, Bibiana |
| Contributors | El-Sohemy, Ahmed |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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