Hyperhomocysteinemia in Asian Indians Living in the United States

Abstract

Hyperhomocysteinemia has been reported in Asian Indians (people from Indian subcontinent) to be related to relatively low plasma levels of folate and vitamin B-12. However, a true ethnic-related characteristic has not been excluded. This study was done to determine whether Asian Indians have high plasma homocysteine compared with Caucasians in the United States in the era of folate fortification, and whether low vitamin B-12 or insulin resistance may account for possible interethnic differences in plasma homocysteine. A total of 227 Asian Indians (131 males and 96 females) and 155 Caucasians (66 males and 89 females) completed a questionnaire for medical, family, and personal history. They had height, weight, and blood pressure measured and fasting blood drawn for routine chemistry, TSH, plasma homocysteine, vitamin B-12, and folate. Oral glucose tolerance test and vitamin B-6 was measured in a subgroup of 66 Asian Indians (47 males and 19 females) and 63 Caucasians (33 males and 30 females). Asian Indians were found to have significantly higher plasma homocysteine than Caucasians (median of 12.6 and 8.0 micro mol/liter, P < 0.0001, respectively) and lower plasma concentrations of B-6 (median 49 vs. 70 nmol/liter; P = 0.05, respectively). Plasma folate was relatively high and similar in both ethnic groups. Plasma vitamin B-12 was significantly lower in Asian Indians than Caucasians (median of 204 vs. 320 pmol/liter, P < 0.0001, respectively). Vitamin B-12 correlated significantly with plasma homocysteine. When vitamin B-12 was between 150 and 379 pmol/liter, the regression curve between vitamin B-12 and homocysteine had significantly different slope in the two ethnic groups (P value < 0.05) and Asian Indians had significantly higher homocysteine for any level of vitamin B-12. Although insulin resistance, measured as insulin area under the curve by oral glucose tolerance test was higher in Asian Indians and correlated significantly with homocysteine, it did not explain inter-ethnic differences in plasma homocysteine in a multivariate analysis. We conclude that Asian Indians living in the United States have significant elevation of plasma homocysteine concentrations despite normal plasma folate. Lower plasma concentrations of vitamin B-12 and lower insulin sensitivity may contribute to this finding but only partially explained the ethnic-related hyperhomocysteinemia of the Asian Indians.

Nutritional Factors, Homocysteine and C677T Polymorphism of the Methylenetetrahydrofolate Reductase Gene in Algerian Subjects with Cardiovascular Disease

“…With regard to the tHCY, there was a significant elevation of plasma tHCY in all patients with CVD. No gender differences were noted for plasma concentrations of tHCY, folate or vitamin B 12 . Plasma total cholesterol concentrations did not differ between gender.…”

“…Plasma tHCY correlated positively with age, urea and creatinine (p <0.05). Vitamin B 12 and folate concentrations as well as urea and creatinine were tightly correlated (p <0.0001).…”

“…The plasma fraction was aliquoted for biochemical analysis. One aliquot was stored at -20°C to await analysis of HCY, folic acid or B 12 .…”

“…Alternatively, an increase in plasma HCY levels may occur because of nutritional deficiencies in essential cofactors or enzyme substrates including vitamin B 12 , folate, and/or vitamin B6. HHCY has been identified as an independent risk factor for cerebral, coronary, and peripheral atherosclerosis, although the pathological mechanism of this risk is not fully understood (11).…”

“…Even though there are many reports about plasma HCY levels in some populations (12), very few studies have been conducted in Algeria (13). To the best of our knowledge and also the increasing prevalence of CVD due to changing lifestyle, gave us an impetus to evaluate the prevalence of MTHFR polymorphism and the changes in plasma HCY, vitamin B 12 , and folate along with lipid profile such as total cholesterol and triglyceride in CVD patients at Sétif of the North East of Algeria.…”