Association of low red blood cell folate concentrations with coronary artery disease in Iranians: a matched case-control study.

BACKGROUND: It is not fully established whether the increasing risk of coronary artery disease (CAD) is associated with high plasma homocysteine levels or components of the homocysteine remethylation pathway, e.g. vitamin B(12) or 5-methyltetrahydrofolate (5-MTHF) in plasma and red blood cells (RBC). In this study, we tested the hypothesis that 5-MTHF in RBC, which represents the long-term folate status of individuals, may be a more reliable marker of homocysteine remethylation pathway disturbances, and its deficiency may be associated with CAD in Iranians. METHODS: Plasma total homocysteine (tHcy), vitamin B(12), and plasma and RBC 5-MTHF were measured in 200 angiographically documented patients and 200 controls matched for sex and age. RESULTS: In the plasma, tHcy levels were significantly higher in cases compared to controls (geometric mean 12.9 +/- 6.5 vs. 10.6 +/- 5.6 micromol/l, p = 0.04). However, RBC 5-MTHF (527.2 +/- 185.9 vs. 461.3 +/- 117.9 nmol/l, p = 0.007) and vitamin B(12) (254.2 +/- 132.8 vs. 182.2 +/- 110.4 pmol/l, p = 0.04) were significantly higher in controls than patients. RBC 5-MTHF was a strong and independent predictor of plasma tHcy (beta = -0.01, p = 0.003, r(2) = 0.19). Subjects in the lowest quartile of red-cell 5-MTHF had a 2.5-fold increased prevalence of CAD compared to subjects in the highest quartile. The association of CAD in the first quartile with red-cell 5-MTHF remained significant when adjusted for plasma tHcy, vitamin B(12), hypertension and hypercholesterolemia (odds ratio, OR 2.3, confidence interval: 1.1-3.9, p = 0.01). However, the association between CAD in the highest quartile and plasma tHcy decreased and became insignificant when adjusted for red-cell 5-MTHF, vitamin B(12), hypertension and hypercholesterolemia (OR 1.27, confidence interval: 0.96-1.69, p = 0.11). CONCLUSION: In this study, the association between CAD and low RBC 5-MTHF was stronger than with plasma 5-MTHF and plasma tHcy levels, indicating that RBC 5-MTHF may be a more stable parameter to study disturbances in the homocysteine remethylation pathway in Iranians.

Distribution of plasma total homocysteine concentrations in the healthy Iranians.

OBJECTIVE: The distribution of plasma total homocysteine concentrations in a population of South West of Iran Shiraz is described to test for differences in homocysteine concentrations among gender and age groups and those levels reported in other populations. DESIGN AND METHODS: Two hundred one healthy males and 201 healthy females aged >15 years from Shiraz, Iran, were randomly selected. Plasma total homocysteine concentrations were measured using high-performance liquid chromatography. RESULTS: The mean plasma homocysteine level was significantly higher in men (geometric mean, 7.3 micromol/l) than in women (geometric mean, 6.3 micromol/l, P < 0.001). The geometric mean levels for ages 15-25, 26-36, 37-47, and 48-58, 59-69, and 70-80 years, were 5.9, 5.4, 5.2, 6.7, 7.3, and 7.6 micromol/l in women and 7.5, 8.7, 5.9, 5.9,7.2, and 9.1 micromol/l in men, respectively. CONCLUSIONS: The homocysteine distribution in a representative sample of people of southwest of Iran indicates age and gender differences, as is found in other populations.