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Using homocysteine as a functional marker, we determined optimal folic acid, vitamin B(12), and vitamin B(6) dosages in 21 pediatric sickle cell disease (SCD) patients (11 HbSS, 10 HbSC; 7-16 years). Daily supplements of folic acid (400, 700, or 1,000 microg), vitamin B(12) (1, 3, or 5 U.S. 1989 RDA), and vitamin B(6) (1 or 3 U.S. 1989 RDA) were gradually increased in an 82-week dose-escalation study. Blood was taken at 9 occasions for measurements of erythrocyte (RBC) and serum folate, plasma vitamin B(12), whole-blood vitamin B(6), and plasma homocysteine. Augmentation of folic acid from 700 to 1,000 microg and vitamin B(12) from 3 to 5 RDA did not further decrease homocysteine. Percentages of patients exhibiting significant individual homocysteine decreases amounted to 43% (folic acid from 0 to 400 microg, vitamins B(12) and B(6) from 0 to 1 RDA), 14% (folic acid from 400 to 700 microg), 24% (vitamin B(12) from 1 to 3 RDA), and 18% (vitamin B(6) from 1 to 3 RDA ). The lowest plasma homocysteine at 82 weeks was 5.9 +/- 2.2 micromol/L. Patients with HbSS had higher RBC folate than HbSC. The entire group exhibited an inverse relation between RBC folate and hemoglobin. We conclude that RBC folate is less valuable for folate status assessment in SCD patients. Optimal dosages are as follows: 700 microg folic acid (3.5-7 U.S. 1989 RDA), 3 U.S. 1989 RDA vitamin B(12) (4.2-6.0 microg), and 3 U.S. 1989 RDA vitamin B(6) (4.2-6.0 mg). A practical daily combination is 1 mg folic acid (4.3-8.5 U.S. 1998 RDA when taken with meals), 6 microg vitamin B(12) (2.5-5 U.S. 1998 RDA), and 6 mg vitamin B(6) (4.6-10 U.S. 1998 RDA). This combination may by simple and relatively inexpensive means reduce these patients' inherently high risk of endothelial damage., (Copyright 2002 Wiley-Liss, Inc.)

Unlabelled: Homocysteine is an intermediate in the folate cycle and methionine metabolism. This study investigated whether formula-fed infants have different plasma total homocysteine to their breastfed counterparts, and during what period any difference developed. Plasma total homocysteine was determined in 53 formula-fed and 15 breastfed healthy low-birthweight babies (< or = 2500 g) around days 10, 20 and 40. Total homocysteine was also measured in human milk. Mean +/- SD plasma total homocysteine levels (micromol l(-1)) at days 10, 20 and 40 were 6.4 +/- 2.6, 6.7 +/- 2.4 and 9.1 +/- 2.4 (breastfed), and 7.5 +/- 3.2, 7.3 +/- 2.1 and 7.4 +/- 1.6 (formula-fed). Homocysteine of breastfed babies at day 40 was higher than that of breastfed babies at day 20 (p < 0.0001), and that of formula-fed counterparts at day 40 (p = 0.002). Homocysteine correlated negatively with formula (day 10) and breast milk (day 40) volume intakes. Median (range) homocysteine in 12 mature human milk samples was 0.30 (not detectable to 0.7) micromol l(-1)., Conclusion: Increasing plasma total homocysteine in breastfed babies to higher levels compared with formula-fed babies may be caused by a gradually developing suboptimal B-vitamin status in lactating women.

Background: Hyperhomocysteinemia is a cardiovascular disease (CVD) risk factor. We determined plasma homocysteine (Hcy) reference values at optimized vitamin status and investigated their influence on the prevalence of hyperhomocysteinemia in healthy adults. Results were compared with those obtained using European Concerted Action Project (ECAP) cutoff values., Methods: Healthy adults (n = 101) received folic acid (5 mg/day) and vitamin B(12) (1 mg/day) for 2 weeks and the same dosages of folic acid and vitamin B(12) plus vitamin B(6) (1 mg. kg(-1). day(-1)) during the following 2 weeks. Hcy concentrations, both fasting and 6-h post-methionine load, were determined at baseline and after 4 weeks., Results: Baseline (4 weeks) fasting and 6-h postload Hcy reference values were 4.7-14.6 (4.1-9.3) and 18.8-49.7 (12.9-35.1) micromol/L, respectively. Mean fasting and 6-h postload Hcy decreased after 4 weeks of vitamin supplementation by 3.5 micromol/L (33.5%) and 8.5 micromol/L (26.3%), respectively. The percentages of subjects exhibiting significant decreases in fasting Hcy following vitamin supplementation were 88% (all subjects), 92% (non-vitamin users), and 72% (vitamin users). The prevalences of hyperhomocysteinemia with use of ECAP cutoff values were 29% for all groups, 29% for men, 27% for premenopausal women, and 53% for postmenopausal women. With vitamin-optimized cutoff values, prevalences were 58%, 58%, 76%, and 89%, respectively. Use of vitamin-optimized cutoff values increased the diagnostic value of fasting Hcy and decreased that of a 6-h postload Hcy compared with use of ECAP cutoff values., Conclusions: Use of vitamin-optimized cutoff values gives rise to high hyperhomocysteinemia pretest probabilities in the general population and, therefore, precludes any meaningful role for Hcy testing. Future demonstration of a beneficial effect of decreasing Hcy on CVD risk would justify use of vitamin-optimized cutoff values for assessment of CVD risk.