Tissue matrix metalloproteinases participate in extracellular matrix remodelling and degradation. Increased expression of MMP-9 and its inhibitor TIMP-1 are linked to unfavourable cardiovascular conditions, including inflammatory damage leading to increased plaque instability(1). Vitamin D insufficiency is associated with higher MMP-9 concentrations, while vitamin D supplementation has been shown to decrease circulating MMP-9 and TIMP-1 concentrations in vitamin D-deficient adults(2).
The effect of vitamin D supplementation (0, 5, 10 and 15 μg cholecalciferol/d) on MMP-9 and TIMP-1 concentrations was investigated in two randomised placebo-controlled double-blind 22-week intervention studies in men and women aged 20–40 years (n 215; during winter 2006–7(3)) and ≥64 years (n 215; during winter 2007–8(4)) from Cork and Coleraine. Fasting serum levels of MMP-9, TIMP-1 and 25-hydroxyvitamin D (25(OH)D) were measured by ELISA at baseline and end point.
BL, baseline; EP, end point (EP). Means in a row with unlike superscript letters were significantly different (P<0.001).
ANOVA showed no baseline differences in the circulating concentrations of MMP-9, TIMP-1 or 25(OH)D between the four treatment groups. Baseline MMP-9 and TIMP-1 concentrations were significantly higher in adults aged 20–40 years (P<0.001) and adults aged ≥64 years (P<0.01) in Coleraine than in Cork. Linear regression analysis showed study centre to be the main predictor of MMP-9 (adjusted R 2 0.474; P<0.001) and TIMP-1 (adjusted R 2 0.326; P<0.001) concentrations in adults aged 20–40 years. In both age-groups pre- and post-intervention 25(OH)D concentrations were not associated with levels of MMP-9, TIMP-1 or MMP-9:TIMP-1. In both age-groups repeated measures analysis revealed no significant effect of the intervention on MMP-9 and TIMP-1 concentrations across the four groups, adjusting for centre, age, gender and BMI.
In conclusion, vitamin D supplementation had no effect on circulating MMP-9 and TIMP-1 concentrations in apparently-healthy adults aged 20–40 and ≥64 years.
We wish to acknowledge the UK Food Standards Agency and the Irish Department of Agriculture, Food & Fisheries through the Food Institutional Research Measure for their support.