Objectives A gradient of increased vascular risk with migration exists across the African diaspora. We investigated the hypothesis that differences in homocysteine/folic acid status contribute to this increased risk.
Design Community cohort study of 73 Afro-Caribbeans in the UK and 151 matched Afro-Caribbeans in Jamaica with no conventional vascular risk factors.
Methods Subjects were compared for baseline characteristics, vascular risk profile, homocysteine (tHcy), folate and B12 concentrations. Endothelium dependent vasodilatation was assessed by measuring the absolute change from baseline in the Reflection Index (RI) of the digital volume pulse during intravenous infusion of albuterol (5 mcg/min, ΔRIALB) and GTN (5 mcg/min, ΔRIGTN). Carotid intima media thickness (CIMT) was measured ultrasonographically in the distal 1 cm of the common carotid artery.
Results UK Afro-Caribbeans had higher tHcy (mean difference 2.3 [95% C.I. 1.3 to 3.4] μmol/L) and lower folate (mean difference 3.2 [95% C.I. 1.8 to 4.7] μg/L) levels. ΔRIALB was 5.1 (95% C.I. 2.5 to 7.6) percentage points lower and CIMT 0.124 (95% C.I. 0.075 to 0.173) mm greater in UK Afro-Caribbeans. Higher tHcy and lower folate concentrations correlated with impaired ΔRIALB and increased CIMT. A 1 μg/L increase in folate concentration was associated with 0.3 [95% C.I. 0.1 to 0.5] percentage point increase in ΔRIALB and 0.002 [95% C.I. 0.001 to 0.006] mm decrease in CIMT, independent of blood pressure, smoking and vascular risk profile.
Conclusions Lower folate concentrations in UK compared with West Indian African-Caribbeans may contribute to the higher stroke risk seen in UK African-Caribbean people.
- endothelium dependent vasodilatation
- intima media thickness
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