Changes in lifestyle and plasma total homocysteine: the Hordaland Homocysteine Study

BACKGROUND: Elevated plasma concentrations of total homocysteine (tHcy) are a risk factor for cardiovascular disease. tHcy is a marker of folate and cobalamin deficiencies and is also related to several lifestyle factors. OBJECTIVE: We examined whether changes in lifestyle influence tHcy over time. DESIGN: A population-based, prospective study was conducted in 7031 subjects from western Norway who constituted 2 age groups (41-42 and 65-67 y) at baseline (1992-1993). The subjects were reinvestigated in 1997-1999 ( follow-up: 6 y). RESULTS: During follow-up, median tHcy concentrations decreased 0.10 (25th and 75th percentiles: -1.24, 1.00) micromol/L in the younger subjects and increased 0.39 (25th and 75th percentiles: -0.99, 1.79) micromol/L in the older subjects. Changes in plasma vitamin status and vitamin supplement use were the strongest determinants of changes in tHcy over time. Each unit increase in plasma folate (nmol/L) and vitamin B-12 (pmol/L) was associated with reductions in tHcy concentrations of 0.2 and 0.1 micromol/L, respectively. Among the younger and older age groups, those who started to take vitamin supplements during follow-up had significant reductions in tHcy concentrations of 0.42 (95% CI: -0.65, -0.20) and 0.41 (-0.78, -0.03) micromol/L, respectively. In the younger subjects who quit smoking, tHcy concentrations decreased 0.54 (-0.91, -0.16) micromol/L. Weight changes were inversely related to tHcy. Both baseline history of cardiovascular disease or hypertension and cardiovascular events during follow-up were significantly associated with changes in tHcy. CONCLUSIONS: Changes in lifestyle factors over time influence tHcy concentrations. These changes are modest when compared with the strong associations between tHcy and lifestyle factors in cross-sectional studies.