Lifestyle and cardiovascular disease risk factors as determinants of total cysteine in plasma: the Hordaland Homocysteine Study

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Abstract
Background: Plasma total homocysteine (tHcy) is a cardiovascular disease risk factor and is related to several components of the established cardiovascular disease risk profile. Cysteine is structurally and metabolically related to homocysteine, but data on its association with cardiovascular disease and cardiovascular disease risk factors are sparse. Objective: Our objective was to search for the determinants of plasma total cysteine (tCys) and compare them with those of tHcy. Design: In this cross-sectional study, we studied 7591 healthy men and 8585 healthy women aged 40–67 y with no history of hypertension, diabetes mellitus, coronary heart disease, or cerebrovascular disease. Results: In the group aged 40–42 y, tCys was significantly higher in men (x̄: 273 μmol/L; 2.5–97.5 percentile: 219–338 μmol/L) than in women (253 μmol/L; 202–317 μmol/L) (P < 0.001). In the group aged 65–67 y, there was no significant sex difference in tCys: men (296 μmol/L; 233–362 μmol/L) and women (296 μmol/L; 234–361 μmol/L). As with tHcy, tCys was positively associated with age, total cholesterol concentration, diastolic blood pressure, and coffee consumption. Body mass index was a strong determinant of tCys but was not related to tHcy. Several factors known to influence tHcy, including smoking status, folate and vitamin intake, heart rate, and physical activity, were not associated or were only weakly associated with tCys. Conclusion: Plasma tCys is strongly related to several factors that constitute the cardiovascular disease risk profile. This should be an incentive to determine the role of tCys in cardiovascular disease.