Association between B vitamin intake and plasma homocysteine concentration in the general Dutch population aged 20-65 y

BACKGROUND: An elevated plasma total homocysteine (tHcy) concentration is associated with an increased risk of cardiovascular diseases. Folate, riboflavin, vitamin B-6, and vitamin B-12 are essential in homocysteine metabolism. OBJECTIVE: The objective was to describe the association between dietary intakes of folate, riboflavin, vitamin B-6, and vitamin B-12 and the nonfasting plasma tHcy concentration. DESIGN: A random sample of 2435 men and women aged 20-65 y from a population-based Dutch cohort examined in 1993-1996 was analyzed cross-sectionally. RESULTS: Univariately, intakes of all B vitamins were inversely related to the plasma tHcy concentration. In multivariate models, only folate intake remained inversely associated with the plasma tHcy concentration. Mean plasma tHcy concentrations (adjusted for intakes of riboflavin, vitamin B-6, vitamin B-12, and methionine and for age, smoking, and alcohol consumption) in men with low (first quintile: 161 microg/d) and high (fifth quintile: 254 microg/d) folate intakes were 15.4 and 13.2 micromol/L, respectively; in women, plasma tHcy concentrations were 13.7 and 12.4 micromol/L at folate intakes of 160 and 262 microg/d, respectively. In men, the difference in the mean plasma tHcy concentration between men with low and high folate intakes was greater in smokers than in nonsmokers (2.8 compared with 1.6 micromol/L) and greater in nondrinkers than in drinkers of >2 alcoholic drinks/d (3.5 compared with 1.4 micromol/L). In women, the association between folate intake and plasma tHcy was not modified by smoking or alcohol consumption. CONCLUSIONS: In this Dutch population, folate was the only B vitamin independently inversely associated with the plasma tHcy concentration. Changing dietary habits may substantially influence the plasma tHcy concentration in the general population.     

The B-vitamin content of baboon (Papio cynocephalus) milk.

1. The B-vitamins in milk from baboons (Papio cynocephalus) at various stages of lactation were measured microbiologically. 2. Mature milk contained, on average (microgram/ml): thiamin 0.18 riboflavin 0.74, nicotinic acid 3.2, folate 0.03, vitamin B6 0.70 vitamin B12 0.002, pantothenic acid 2.63, biotin 0.0065. 3. Colostrum contained much less vitamin B6 and pantothenic acid than mature milk; otherwise, there were only slight changes in composition as lactation progressed. Neither these changes, nor the absolute values, resembled those for human or cow's milk. 4. The average daily secretion of B-vitamins in milk represented less than 10% of the mother's dietary intake; that of folate was less than 0.5% of the mother's dietary intake. 5. Baboon milk was calculated to provide infants with approximately the following quantities of B-vitamins (/d): thiamin 0.06 mg, riboflavin 0.25 mg, nicotinic acid 1.1 mg, folate 10 microgram, vitamin B6 0.25 mg, vitamin B12 0.7 microgram, pantothenic acid 0.9 mg, biotin 2.2 microgram.     

Relationship between dietary folate intakes,maternal plasma total homocysteine and B-vitamins during pregnancy and fetal growth in Japan

Background Adequate folate status in pregnancy is important for satisfactory pregnancy outcome. Aim of the Study The objective of the present study was to evaluate folate status in healthy pregnant women by assessing dietary folate intakes and measuring changes in folate-related biomarkers including plasma tHcy, serum vitamin B₁₂ (B₁₂), and serum and RBC folate concentrations in each trimester and to examine their relation to fetal growth. Methods From 94 pregnant women, 3-day-dietary records were obtained and blood was collected for plasma total homocysteine (tHcy), serum B₁₂, and serum and red-blood cell (RBC) folate measurements. Infant anthropometric measurements were made immediately after birth. Results Average folate intake was less than 300 μg/day with a mean energy intake of about 1800 kcal. Mean serum and RBC folate concentrations declined significantly during gestation (p < 0.05). Mean serum B₁₂ also significantly decreased (p < 0.01), whereas plasma tHcy increased from 5.1 in the first trimester to 5.9 μmol/l in the third trimester (p < 0.01). Multiple regression analyses, after controlling for maternal age, parity and pre-pregnancy body-mass index indicated that a 1.0 μmol/l increase in plasma tHcy in the third trimester corresponded to a 151 g decrease in birth weight (p < 0.01). Neither B₁₂ nor folate concentrations in all three trimesters showed any significant associations with birthweight. Plasma pyridoxal-5′-phosphate concentrations were markedly low, and were consistent with low intake of vitamin B₆ in our population. Conclusion Our data suggest that higher plasma tHcy in the third trimester is a predictor of lower birth weight. In general, the dietary intake of B-vitamins and energy may be inadequate in our population, suggesting intervention is necessary.     

Changes in predictors and status of homocysteine in young male adults after a dietary intervention with vegetables, fruits and bread

BACKGROUND: Elevated plasma total homocysteine (p-tHcy) is associated with increased risk of cardiovascular disease, and an inverse association has been shown between the dietary intake of B-vitamins, B-vitamin profile and the concentration of p-tHcy. AIM OF THE STUDY: The main objective of this investigation was to study the effect of a dietary intervention focusing on an increased intake of vegetables, fruits and bread. The effect of the dietary intervention was determined by the changes in plasma concentrations of tHcy, cysteine (cys), riboflavin, flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) and serum concentrations of folate and vitamin B(12). METHOD: An intervention study with duration of 5 months, including 541 male recruits from the Norwegian National Guard, Vaernes and a control group, including 209 male recruits from the Norwegian Army, Heggelia. RESULTS: The dietary intervention resulted in decreased concentration of p-tHcy (-10%, P = 0.002), p-cys (-6%, P < 0.001) and FMN (-11%, P = 0.310) and increased concentration of riboflavin (+23%, P < 0.001) and FAD (+10%, P = 0.008) in the intervention group compared with the control group. The change in p-tHcy concentration was positively related to the change in the concentration of p-cys (P < 0.001) and FMN (P = 0.035) and inversely related to the change in concentration of folate (P = 0.021). CONCLUSIONS: A dietary intervention program focusing on an increased intake of vegetables, fruits and bread showed a favourable effect on the concentration of p-tHcy and its metabolites. Our findings suggest that the changes in the concentration of p-cys, folate and FMN seem to be predictors of changes in the p-tHcy concentration.     

B vitamin status and concentrations of homocysteine and methylmalonic acid in elderly German women

BACKGROUND: Prior investigations found that elderly persons are at higher risk than are younger persons for B vitamin deficiency, which leads to elevated plasma total homocysteine (tHcy) concentrations that are associated with an increased risk for certain diseases such as coronary artery disease. To date, published data have shown decreased vitamin status and elevated tHcy among the elderly. OBJECTIVE: We evaluated the dietary intake and the blood status of various B vitamins and tHcy and methylmalonic acid (MMA) concentrations in 178 younger (60-70-y-old) female seniors. DESIGN: Dietary intake was assessed with a 3-d diet record. Thiamine, riboflavin, and vitamin B-6 activity coefficients of erythrocyte transketolase (EC 2.2.1.1), erythrocyte glutathione reductase (EC 1.6.4.2), and erythrocyte alpha-aspartic aminotransferase (EC 2.6.1.1) were used as functional indexes for the status of the 3 vitamins, respectively. Concentrations of serum and red blood cell folate, serum cobalamin and MMA, and plasma tHcy were measured. RESULTS: Indexes of thiamine, pyridoxine, and cobalamin indicated insufficient status in one-third of the women, whereas tHcy and MMA concentrations were elevated in 17.4% and 9.6% of the women, respectively. An association between vitamin intake and vitamin concentration in the blood was found only for folate. The mean tHcy concentration in subjects in the lowest quartile of serum folate concentration was 23% higher than that in subjects in the highest quartile. There was no association between riboflavin and tHcy concentrations. MMA was positively correlated with age and inversely correlated with serum cobalamin concentration. CONCLUSIONS: Even in younger, well-educated, female seniors, the prevalence of low B vitamin status and elevated plasma tHcy concentration is high. Thiamine, pyridoxine, folate, and cobalamin supplementation should be considered.     

Longitudinal change in plasma total homocysteine during pregnancy and postpartum in Brazilian women and its relation with folate status and other factors

Fasting plasma total homocysteine (tHcy) concentration was determined in a cohort of pregnant Brazilian women (n = 46) supplemented with folic acid from the second trimester of pregnancy. Blood samples were obtained in the first and third trimesters from all women, and 30-40 days postpartum from seventeen women. Plasma tHcy decreased during pregnancy from 10.3 to 8.7 micromol/L, and was 11.6 micromol/L in the postpartum. Plasma and erythrocyte folate increased, consistent with use of the folate supplement, but decreased slightly in the postpartum, whereas the opposite occurred for plasma vitamin B12. tHcy was inversely correlated with plasma and erythrocyte folate in the third trimester (r = -0.585 and -0.460, respectively). This relationship occurred despite the fact that all women had attained what could be considered adequate levels of folate indices. Furthermore, the change (third trimester minus first trimester levels) of tHcy was inversely correlated (p < 0.01) with the changes in plasma (r = -0.573) and erythrocyte folate (r = -0.525). tHcy had no correlation in any of the periods tested with plasma vitamin B12, plasma albumin, hematocrit, hemoglobin, iron indices, dietary intakes of folate, vitamins B12 and B6, and levels of folate supplement.     

Frequent consumption of milk, yogurt, cold breakfast cereals, peppers, and cruciferous vegetables and intakes of dietary folate and riboflavin but not vitamins B-12 and B-6 are inversely associated with serum total homocysteine concentrations in the US population

BACKGROUND: Elevated circulating total homocysteine (tHcy) is an independent risk factor for vascular diseases. OBJECTIVE: We investigated the relation between dietary intakes and serum tHcy in the US population. DESIGN: Data from the third National Health and Nutrition Examination Survey (1988-1994) were used to investigate the associations between food consumption frequency and dietary B vitamin intakes and serum tHcy in 5996 persons. RESULTS: Multivariate-adjusted tHcy concentrations were approximately 15.2% higher in subjects who never consumed milk than in those who consumed milk >30 times/mo, approximately 6.4% higher in subjects who never consumed yogurt than in those who consumed yogurt >15 times/mo, approximately 7.4% higher in subjects who never consumed cold breakfast cereals than in those who consumed cold breakfast cereals >30 times/mo, approximately 6.3% higher in subjects who never consumed peppers (includes red, yellow, green, and hot chili peppers) than in those who consumed peppers >30 times/mo, and approximately 16.5% higher in subjects who never consumed cruciferous vegetables than in those who consumed cruciferous vegetables >30 times/mo. Consumption of citrus fruit and juices, cheese, meats, coffee, or tea had no significant association with tHcy. Folate (beta=-0.0017, P for trend=0.004) and riboflavin (beta=-0.2851, P for trend=0.027), but not vitamin B-6 (beta=0.0505, P for trend=0.70) and cobalamin (beta=-0.0035, P for trend=0.58), were inversely related to serum tHcy after adjustment for confounders. CONCLUSIONS: In this population-based study, milk, yogurt, cold breakfast cereals, peppers, and cruciferous vegetables were inversely related to serum tHcy. This association may be explained by increased intakes of folate and riboflavin.     

Long-term consumption of a raw food diet is associated with favorable serum LDL cholesterol and triglycerides but also with elevated plasma homocysteine and low serum HDL cholesterol in humans

High consumption of vegetables and fruits is associated with reduced risk for cardiovascular disease. However, little information is available about diets based predominantly on consumption of fruits and their health consequences. We investigated the effects of an extremely high dietary intake of raw vegetables and fruits (70-100% raw food) on serum lipids and plasma vitamin B-12, folate, and total homocysteine (tHcy). In a cross-sectional study, the lipid, folate, vitamin B-12, and tHcy status of 201 adherents to a raw food diet (94 men and 107 women) were examined. The participants consumed approximately 1500-1800 g raw food of plant origin/d mainly as vegetables or fruits. Of the participants, 14% had high serum LDL cholesterol concentrations, 46% had low serum HDL cholesterol, and none had high triglycerides. Of raw food consumers, 38% were vitamin B-12 deficient, whereas 12% had an increased mean corpuscular volume (MCV). Plasma tHcy concentrations were correlated with plasma vitamin B-12 concentrations (r = -0.450, P < 0.001), but not with plasma folate. Plasma tHcy and MCV concentrations were higher in those in the lowest quintile of consumption of food of animal origin (P(trend) < 0.001). This study indicates that consumption of a strict raw food diet lowers plasma total cholesterol and triglyceride concentrations, but also lowers serum HDL cholesterol and increases tHcy concentrations due to vitamin B-12 deficiency.     

Fluctuations in dietary methionine intake do not alter plasma homocysteine concentration in healthy men

A moderate elevation in plasma total homocysteine (tHcy) has been established as an independent risk factor for vascular disease. An important exogenous source of homocysteine is methionine found in foods rich in animal protein. We investigated the response of tHcy to fluctuations in methionine intake in a cross-over intervention trial (two arms). Healthy men (n = 52; 19-29 y) were screened for habitual methionine intake using a food-frequency questionnaire. Subjects in the top quartile for methionine intake (n = 13), with a baseline fasting tHcy of 7.01 +/- 1.84 micromol/L (mean +/- SD), were randomly assigned to receive either a low-methionine intervention diet for 1 wk followed by a control diet for 1 wk or vice-versa. Simultaneously, those in the bottom quartile for methionine intake (n = 11), with a fasting plasma tHcy of 9.79 +/- 7. 20 micromol/L (mean +/- SD), received either a high methionine intervention diet for 1 wk followed by a control diet or vice-versa. All subjects had serum folate, red-cell folate, serum vitamin B-12 and plasma pyridoxal phosphate (PLP) concentrations within normal ranges. During the intervention, subjects in the top quartile for methionine intake reduced their daily methionine intake 79%, from 1969 +/- 639 to 407 +/- 83 mg/d (P: 相似文献   

Reference range of total serum homocysteine level and dietary indexes in healthy Greek schoolchildren aged 6-15 years

Elevated total serum homocysteine (tHcy) may be a possible risk factor for CVD. A 5 micromol/l increase in tHcy is associated with an approximately 70 % increase in relative risk of CVD in adults. Data for children and adolescents are, however, limited. The purpose of the present study was to provide a reference range for tHcy and investigate any relationship between tHcy and nutritional indexes in a Greek paediatric population. tHcy, folate, vitamin B12 levels and dietary indexes were measured in 520 healthy schoolchildren (274 boys, 246 girls) aged 6-15 years. As in adults, the tHcy distribution skewed to the right, with a geometric mean for both genders of 7.4 (range 3.4-29 micromol/l). Concentrations were lower in young children and increased with age. No statistically significant difference in tHcy level was observed between gender. The 95th percentiles for the three age groups were as follows: 6-9 years, 9.98 micromol/l; 10-12 years, 10.62 micromol/l; 13-15 years, 14.4 micromol/l. Using Pearson's coefficient analysis, tHcy level was correlated with age, serum folate, BMI and systolic blood pressure. Dietary analysis showed that folate, vitamin B12 and fibre intake were inversely related with tHcy; conversely, sugar and fat were positively associated with tHcy. However, in multiple linear regression analysis, only age (odds ratio 0.246, P < 0.05) and folate (odds ratio -0.346, P < 0.05) were significantly and independently associated with tHcy. This study provides age-specific reference data regarding tHcy concentration in a Greek paediatric population. tHcy levels increased as a function of age. Serum folate levels were significantly and independently associated with tHcy levels.     

Correlates of total plasma homocysteine: folic acid, copper, and cervical dysplasia

We examined correlates of total plasma homocysteine (tHcy) in 294 subjects with cervical intraepithelial neoplasia and 170 control subjects. Associations of tHcy with risk factors for cervical intraepithelial neoplasia and 24-h intakes and biochemical indices of nutrients were examined. Plasma and red blood cell folate and plasma B(12) were strong inverse correlates of tHcy (r = -0.35, -0. 31, and -0.27, respectively). Plasma copper and severity of dysplasia were positively correlated with tHcy (r = 0.14 and 0.21, respectively). A stepwise regression model that included red blood cell folate, plasma copper, grade of dysplasia, ethnicity, intake of polyunsaturated fatty acids, plasma vitamin B(12), intake of fat, and oral contraceptive use explained 29% of the variation in tHcy. Two hundred thirty-five subjects with cervical intraepithelial neoplasia were randomized to receive folic acid (10 mg/d) or placebo for 6 mo. After 2, 4, and 6 mo, mean tHcy in the folate-supplemented group (7.2 +/- 1.8, 7.0 +/- 1.9, and 7.0 +/- 2.3 micromol/L, respectively) was significantly lower than baseline and the placebo group at 2, 4, and 6 mo (8.9 +/- 3.1, 8.4 +/- 3.0, and 8.9 +/- 3.1 micromol/L, respectively). Supplementation lowered tHcy even in subjects in the highest quintile of baseline folate. Folate, vitamin B(12), copper, and severity of dysplasia are associated with tHcy. Folate supplementation significantly lowers tHcy even in folate-replete subjects.     

Folate intake, lifestyle factors, and homocysteine concentrations in younger and older women

BACKGROUND: An elevated total homocysteine (tHcy) concentration is considered to be an independent risk factor for cardiovascular diseases and has also been associated with an increased risk of neural tube defects. OBJECTIVE: The objective of this study was to investigate folate intake, folate status, and the association between folate intake, other dietary and lifestyle factors, and tHcy concentrations in young and older women. DESIGN: tHcy concentrations were measured in 290 young women aged 25-30 y and in 288 older women aged 60-65 y. All participants completed questionnaires about factors including lifestyle, health, and use of vitamin supplements. Red blood cell folate was measured in 204 of the participants. A subgroup of 258 participants completed dietary records. RESULTS: Median tHcy was 7.6 micromol/L (range: 6.5-8.9) in the younger women and 9.4 micromol/L (7.7-11.1) in the older women. Folate intake from diet was 283 (224-348) and 268 (210-326) microg/d, respectively, in the 2 age groups. Folic acid intake from supplements (P: < 0.001 for the younger women and P: = 0.026 for the older women) and total folate intake (P: = 0.024 and P: = 0.079) were inversely associated with log tHcy in multiple linear regression analyses. Smoking status, coffee consumption, systolic blood pressure, and body mass index were positively associated and estrogen replacement therapy and tea consumption were inversely associated with log tHcy in some of the models. CONCLUSIONS: According to the criteria used, between 1% and 36% of the women had suboptimal folate intake. Folic acid is a strong predictor of tHcy concentration; however, several dietary and other lifestyle factors seem to be important as well.     

Vegetables, fruits, and related nutrients and risk of breast cancer: a case-control study in Uruguay

To evaluate whether the protective effect associated with vegetables and fruits in breast cancer could be explained by nutrients and bioactive substances present in these plant foods, we carried out a case-control study in Uruguay including 400 cases and 405 controls. The intake of vegetables, fruits, and related nutrients was estimated with a food frequency questionnaire on 64 food items. This questionnaire allowed the calculation of total energy intake, and nutrients were calorie adjusted by the residuals method. Odds ratios for study variables were estimated by unconditional multiple logistic regression. Total vegetable, total fruit, dietary fiber, vitamin C, vitamin E, lycopene, folate, and total phytosterol intakes were inversely associated with breast cancer risk [4th quartile odds ratio for total vegetable intake = 0.41, 95% confidence interval = 0.26-0.65, p (for trend) = 0.004]. The association with total vegetable intake was not independent of lycopene intake. The results related to vegetable and nutrient intakes are consistent with antioxidant and antiestrogenic effects. This could be mediated, among other nutrients, by dietary fiber and lycopene intake. The role of other unmeasured phytochemicals, correlated with dietary fiber and lycopene intakes, cannot be ruled out.     

Serum homocysteine concentration as a marker of nutritional status of healthy subjects in Crete, Greece

BACKGROUND: Dietary habits are an important determinant of serum homocysteine (tHcy), which may be a marker rather than a cause of progression of the atherosclerotic process. The aim of the present study was to evaluate the nutritional status, and to determine the serum tHcy concentrations in healthy subjects who live in rural areas of Crete, and who theoretically follow a contemporary Mediterranean-style diet. METHODS: Serum tHcy, folate, vitamin B(12), creatinine, glucose, and the lipid profile, were measured in 203 (141 men and 62 women) healthy subjects, aged 33-78 years. The major risk factors for cardiovascular disease such as age, gender, cigarette smoking, obesity were recorded and dietary data were assessed using a 3-day weighed food intake record. RESULTS: Our population had high serum tHcy, low serum folate concentrations and lower than the traditional Cretan dietary folate intake [median (range): 12.0 (3.6-44.7) micromol L(-1), 7.9 (1.9-15.5) ng mL(-1) and 241 (68-1106) microg, respectively]. Dietary intake of fibre, omega-3, and mono- or/ polyunsaturated fatty acids was also low. An inverse relation was observed between serum tHcy concentrations and serum folate (r = -0.28; P < 0.01) and vitamin B(12) levels (r = -0.33; P < 0.001). CONCLUSIONS: Nowadays, the Cretan diet has changed towards a more westernized eating pattern. Given the analytic difficulties in determining the amount of folate in food and the inverse correlation between serum tHcy and folate levels, serum tHcy concentrations may be a useful marker for nutritional status, especially folate deficiency, in healthy subjects.     

Plasma total homocysteine,folate, and vitamin B12 status in Korean adults

Elevated plasma total homocysteine (tHcy) levels have been established as a risk factor for occlusive cardiovascular disease. Also known is that plasma folate and vitamin B12 influence homocysteine metabolism as cosubstrate and cofactor, respectively. However, not much information is available describing plasma tHcy levels and their relationship to plasma folate and vitamin B12 status in Koreans. We measured the plasma levels of tHcy, folate, and vitamin B12 in 195 adults (99 males, 96 females; 23-72 y old in the lower middle class). The mean plasma tHcy levels of males, 11.18 +/- 3.88 micromol/L, was significantly higher (p < 0.001) than that of females, 9.20 +/- 2.65 micromol/L. The distribution of tHcy levels of males showed a wide range, 3-50 micromol/L, with a long tail toward higher values. Thus the incidence of hyperhomocysteinemia (> or = 5 micromol/L) in males, 10.1%, was significantly higher (< 0.02) than the 2.1% in females. As age increased, plasma tHcy levels tended to be higher in females. Therefore, sex differences in plasma tHcy levels disappeared in subjects over fifty. On the other hand, both plasma folate (6.47 +/- 3.06 vs 7.96 +/- 3.55 ng/mL, p < 0.01) and vitamin B12 levels (537.0 +/- 222.0 vs. 664.1 +/- 309.8 ng/mL, p < 0.01) were significantly lower in males than in females. A plasma folate deficiency (< 3.0 ng/mL) was found in 6.1% of males and 2.1% of females. And a vitamin B12 deficiency (< 150 pg/mL) was detected in 2.0% and 1.0%, respectively. Plasma tHcy levels were related with inversely plasma concentrations of folate (r = -0.37249, p < 0.001) as well as vitamin B12 (r = -0.22560, p < 0.01) in both sexes. Plasma levels of tHcy and the prevalence of hyperhomocysteinemia in Korean adults are similar to findings in the West. Our results indicate that male adults may be in worse condition for cardiovascular disease (CVD) than females. And improving folate and vitamin B12 status may reduce plasma tHcy level, which may be more important in males.     

Plasma homocysteine concentrations in Greek children are influenced by an interaction between the methylenetetrahydrofolate reductase C677T genotype and folate status

Risk factors established at young ages may set the stage for later cardiovascular disease (CVD). Elevated total homocysteine (tHcy) in blood is an emerging risk factor for CVD, yet few studies have been conducted in children, especially in the Mediterranean. We described plasma tHcy concentrations in a group of healthy Greek children and examined its relation with physiologic, metabolic, and genetic variables. Fasting blood samples were collected from 186 students, 11.6 +/- 0.4 years old, and tHcy, folate, vitamin B-12, and routine biochemistry variables in plasma were measured. The methylenetetrahydrolate reductase (MTHFR) C677T genotype was determined and anthropometric and dietary data were obtained. The distribution of tHcy was positively skewed with a median of 7.9 micromol/L (mean: 8.2 +/- 2.3 micromol/L; range: 4.4-22.2 micromol/L). tHcy was inversely related to plasma folate (r = -0.34, P < 0.0001), vitamin B-12 (r = -0.20, P = 0.008), and glucose (r = -0.15, P = 0.045). An interaction between the MTHFR genotype and plasma folate on tHcy was detected (P = 0.047). Specifically, the homozygous mutant TT genotype was associated with higher tHcy only in children with lower plasma folate (< 19.9 nmol/L), (P = 0.012). In our sample of healthy Greek children, plasma tHcy concentrations were higher than values reported in children of Northern European descent and were associated with folate, vitamin B-12, and glucose in plasma. The results also show that, similar to adults, plasma folate concentration is important in determining the contribution of the MTHFR C677T mutation to tHcy concentrations in children.     

Effect of a voluntary food fortification policy on folate, related B vitamin status, and homocysteine in healthy adults

BACKGROUND: Mandatory folic acid fortification of food is effective in reducing neural tube defects and may even reduce stroke-related mortality, but it remains controversial because of concerns about potential adverse effects. Thus, it is virtually nonexistent in Europe, albeit many countries allow food fortification on a voluntary basis. OBJECTIVE: The objective of the study was to examine the effect of a voluntary but liberal food fortification policy on dietary intake and biomarker status of folate and other homocysteine-related B vitamins in a healthy population. DESIGN: The study was a cross-sectional study. From a convenience sample of 662 adults in Northern Ireland, those who provided a fasting blood sample and dietary intake data were examined (n = 441, aged 18-92 y). Intakes of both natural food folate and folic acid from fortified foods were estimated; we used the latter to categorize participants by fortified food intake. RESULTS: Fortified foods were associated with significantly higher dietary intakes and biomarker status of folate, vitamin B-12, vitamin B-6, and riboflavin than were unfortified foods. There was no difference in natural food folate intake (range: 179-197 microg/d) between the fortified food categories. Red blood cell folate concentrations were 387 nmol/L higher and plasma total homocysteine concentrations were 2 micromol/L lower in the group with the highest fortified food intake (median intake: 208 microg/d folic acid) than in the nonconsumers of fortified foods (0 microg/d folic acid). CONCLUSIONS: These results show that voluntary food fortification is associated with a substantial increase in dietary intake and biomarker status of folate and metabolically related B vitamins with potential beneficial effects on health. However, those who do not consume fortified foods regularly may have insufficient B vitamin status to achieve the known and potential health benefits.     

Determinants of plasma total homocysteine concentration in the Framingham Offspring cohort

BACKGROUND: Established determinants of fasting total homocysteine (tHcy) concentration include folate and vitamin B-12 status, serum creatinine concentration, and renal function. OBJECTIVE: Our objective was to examine the relation between known and suspected determinants of fasting plasma tHcy in a population-based cohort. DESIGN: We examined the relations between fasting plasma tHcy concentrations and nutritional and other health factors in 1960 men and women, aged 28-82 y, from the fifth examination cycle of the Framingham Offspring Study between 1991 and 1994, before the implementation of folic acid fortification. RESULTS: Geometric mean tHcy was 11% higher in men than in women and 23% higher in persons aged > or = 65 y than in persons aged < 45 y (P < 0.001). tHcy was associated with plasma folate, vitamin B-12, and pyridoxal phosphate (P for trend < 0.001). Dietary folate, vitamin B-6, and riboflavin were associated with tHcy among non-supplement users (P for trend < 0.01). The tHcy concentrations of persons who used vitamin B supplements were 18% lower than those of persons who did not (P < 0.001). tHcy was positively associated with alcohol intake (P for trend = 0.004), caffeine intake (P for trend < 0.001), serum creatinine (P for trend < 0.001), number of cigarettes smoked (P for trend < 0.001), and antihypertensive medication use (P < 0.001). CONCLUSIONS: Our study confirmed, in a population-based setting, the importance of the known determinants of fasting tHcy and suggested that other dietary and lifestyle factors, including vitamin B-6, riboflavin, alcohol, and caffeine intakes as well as smoking and hypertension, influence circulating tHcy concentrations.     

Dietary pattern is associated with homocysteine and B vitamin status in an urban Chinese population

To identify existing dietary patterns and examine associations between these patterns and plasma homocysteine and B vitamin concentrations in an urban Chinese population living in Beijing (n = 119), dietary information was collected with a food frequency questionnaire designed for this population. Plasma homocysteine and B vitamin concentrations were examined. Food group variables, expressed as percentages of total energy intake, were entered into cluster analysis to define three distinct dietary pattern groups. The prevalence of high homocysteine (>11 micromol/L for women and 12 micromol/L for men), was 31.9%; of low folate (<6.8 nmol/L), 36.2%; of low vitamin B-12 (<221 pmol/L), 36.9%; and of low vitamin B-6 (<30 nmol/L), 16.0%. The three dietary patterns derived were defined by relatively greater intake of 1) fruit and milk, 2) red meat and 3) refined cereals. More than 40% of subjects in the refined cereals group had high plasma homocysteine and low plasma folate concentrations, and 67% had low plasma vitamin B-12 concentrations. Those following the refined cereals pattern were 4 and 5.2 times more likely to have high homocysteine and low vitamin B-12 concentrations, respectively, relative to the fruit and milk dietary pattern group (P < 0.01), after adjustment for potential confounders. High intake of refined cereals was associated with low B vitamin and high homocysteine concentrations, whereas the pattern high in fruit and milk was associated with the lowest homocysteine. Dietary patterns appear to play an important role in the micronutrient and homocysteine status of these Chinese adults.     

Plasma homocysteine concentration is decreased by dietary intervention

High plasma total homocysteine (tHcy) concentration is reported to be a risk factor for vascular diseases. We investigated the extent to which serum folate and plasma tHcy respond to a high intake of natural folate from food. Thirty-seven healthy females volunteered t o participate in a crossover dietary intervention. The study included a baseline period and two 5-week diet periods (low- and high-folate diets) with a 3-week washout in between. The low-folate diet contained one serving of both vegetables and fruit/d, while during the high-folate diet the subjects ate at least seven servings of vegetables, berries, and citrus fruit/d. Serum and erythrocyte (RBC) folate, serum vitamin B (12), and plasma tHcy concentrations were measured at the base-line and at the end of each diet period. The mean concentrations of serum and RBC folate were 11.0 (SD 3.0) nmol/l and 412 (SD 120) nmol/l at the end of the low-folate diet and 78 (95 % CI 62, 94) % and 14 (95 % CI 8, 20) % higher in response to the high-folate diet (P< 0.001). The serum concentration of vitamin B12 remained unchanged during the intervention. The mean plasma tHcy concentration was 8.0 pmol/ at the end of the low-folate diet and decreased by 13 (95% CI 9, 18) % in response to the high-folate diet (P<0.001). In conclusion, a diet high in fresh berries, citrus fruit, and vegetables effectively increases serum and RBC folate and decreases plasma homocysteine.