title: Vitamin supplementation and blood pressure in Type 2 diabetes.
abstract: OBJECTIVE
  Vitamin D levels are inversely related to blood pressure. Given that low sun exposure can create a greater reliance on dietary sources of vitamin D, we aimed to determine whether dietary vitamin D and blood pressure associations differ between periods of low and high sun exposure.
  
  
  METHODS
  Dietary intake, vitamin supplementation, blood pressure, and anthropometric parameters were assessed each season for 1 year (174 adults with Type 2 diabetes). Separate linear regression models were constructed for high and low sun exposure periods to examine associations of systolic blood pressure with dietary vitamin D intake and vitamin supplement use (adjusted for age, gender, BMI, ethnicity, smoking, alcohol, physical activity, antihypertensive medication and nutrient intake). Robustness of findings was confirmed with within-subject repeated measures analysis, including an interaction term for sun exposure period.
  
  
  RESULTS
  Vitamin D intake from food sources was low year-round and no conclusive association with blood pressure was identified during either period. Systolic blood pressure was 5.1 mmHg lower during the low sun exposure period (95% CI 0.5-9.7) in daily supplement users compared with non-users. The interaction term between supplement use and sun exposure period was significant (low sun exposure* no supplement, P = 0.02). Systolic blood pressure was relatively stable in users (low and high sun exposure periods, respectively, mean ± SE: 135.2 ± 2.6 mmHg and 134.2 ± 2.5 mmHg), but not in non-users (140.2 ± 2.7 mmHg and 130.5 ± 2.5 mmHg).
  
  
  CONCLUSIONS
  Vitamin supplementation may stabilize systolic blood pressure in adults with Type 2 diabetes across seasons.
authors.affiliation: Division of Clinical Epidemiology, Department of Medicine, McGill University Health Centre, Montreal, Canada.
authors.forename: S
authors.initials: S
authors.lastname: Jarvandi
authors.forename: L
authors.initials: L
authors.lastname: Joseph
authors.forename: R
authors.initials: R
authors.lastname: Gougeon
authors.forename: K
authors.initials: K
authors.lastname: Dasgupta
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000178:diet therapy / Q000378:metabolism* / Q000503:physiopathology*; D019587:Dietary Supplements; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D013472:Sunlight; D014807:Vitamin D / Q000378:metabolism*; D014808:Vitamin D Deficiency / Q000178:diet therapy / Q000378:metabolism* / Q000503:physiopathology
chemical_list: D014807:Vitamin D