Folate status of Ghanaian populations in London and Accra

Migration to the UK is associated with higher incidence of stroke in African populations. A low folate status has been associated with increased risk of stroke, likely to be mediated through raised plasma homocysteine concentrations. We conducted a cross-sectional study to compare blood folate and homocysteine concentrations in eighty healthy Ghanaian migrants living in London matched by sex, age and occupation to 160 individuals from an urban population in Accra, Ghana. Folate intake was determined using three 24 h recalls. Fasting blood samples were collected for the determination of serum and erythrocyte folate and plasma homocysteine concentrations and the methylenetetrahydrofolate reductase (MTHFR) 677C --> T polymorphism. Reported mean folate intake was 20 % lower in London compared with Accra (P < 0.001). However, serum folate was 44 % higher, erythrocyte folate 30 % higher and plasma homocysteine was 26 % lower in subjects from London compared with those from Accra (P < 0.001). These differences persisted after adjusting for confounders including the MTHFR 677C --> T mutation, which was rare in both populations. Although there were no associations between dietary folate intake and blood folates (P>0.05), folic acid supplement use, which was more prevalent in London than Accra (25 and 10 %, respectively, P = 0.004) was associated with erythrocyte folate in both populations (P < 0.01). The main predictors of plasma homocysteine concentrations were erythrocyte folate and male sex (P < 0.001). Findings from the present study suggest that migration from Ghana to the UK results in improvement of biomarkers of folate status despite the fact that reported dietary intake of folate was apparently lower in subjects from London.