Riboflavin is a determinant of total homocysteine plasma concentrations in end-stage renal disease patients

The effect of thiamine (vitamin B(1)) or riboflavin (vitamin B(2)) availability on fasting total homocysteine (tHcy) plasma levels in end-stage renal disease patients is unknown. A cross-sectional study was performed in a population of non-vitamin supplemented patients maintained on continuous ambulatory peritoneal dialysis. Red blood cell availability of thiamine (alpha-ETK) and of riboflavin (alpha-EGR), along with other predictors of tHcy plasma levels, was considered in the analysis. There was a linear association of alpha-EGR with tHcy plasma concentrations (P = 0.009), which was not observed for alpha-ETK. Among red blood cell vitamins, alpha-EGR was the only predictor of tHcy levels (P = 0.035), whereas alpha-ETK, red blood cell pyridoxal-5-phosphate supply (alpha-EGOT) and red blood cell folate levels had no effect. The risk for having a high tHcy plasma levels within the fourth quartile (plasma tHcy >38.3 micromol/L) was increased by an alpha-EGR > median (odds ratio, 4.706; 95% confidence interval, 1.124 to 19.704; P = 0.026). By way of contrast, alpha-ETK had no effect in these analyses. Independent predictors of tHcy plasma levels were serum albumin, alpha-EGR, red blood cell folate, and certain MTHFR genotypes. A logistic regression analysis showed that the MTHFR genotype is a predictor for having a tHcy plasma concentration within the fourth quartile. In summary, riboflavin availability, as measured by alpha-EGR, is a determinant of fasting tHcy plasma levels in peritoneal dialysis patients. This finding may have implications for tHcy lowering therapy in individuals with end-stage renal disease.

The relationship between riboflavin and plasma total homocysteine in the Framingham Offspring cohort is influenced by folate status and the C677T transition in the methylenetetrahydrofolate reductase gene

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate, the methyl donor for remethylation of homocysteine to methionine. The C677T MTHFR polymorphism is associated with mild hyperhomocysteinemia, but only in the presence of low folate status. Because MTHFR contains flavin adenine dinucleotide (FAD) as a prosthetic group, riboflavin status may also influence homocysteine metabolism. The objective of this study was to examine the association between riboflavin status and fasting plasma total homocysteine (tHcy) concentration while also considering MTHFR C677T genotype and folate status. The study was conducted using fasting plasma samples (n = 450) from the fifth examination of the Framingham Offspring Study cohort. All persons with the TT genotype and age- and sex-matched sets of individuals with the CT and CC genotypes were selected for determination of plasma riboflavin and flavin mono- and dinucleotide levels. Plasma riboflavin was associated with tHcy concentrations, but the association was largely confined to persons with plasma folate <12.5 nmol/L and TT genotype. In these persons, the mean tHcy among individuals with riboflavin levels <6.89 nmol/L was 14.5 micromol/L, whereas the mean tHcy for those with riboflavin > or = 11 nmol/L was 11.6 micromol/L (P-trend <0.03). Plasma flavin nucleotides were unrelated to tHcy concentrations. Our data suggest that riboflavin status may affect homocysteine metabolism, but only in a small segment of the population who have both low folate status and are homozygotes for the MTHFR C677T mutation.

Dietary sugars and micronutrient dilution in normal adults aged 65 years and over

OBJECTIVE

To examine the relationship between non-milk extrinsic sugars (NMES) concentration and micronutrient intakes and status in free-living older people.

DESIGN

The National Diet and Nutrition Survey of people aged 65 years and over; a cross-sectional study in Britain in 1994/5.

SUBJECTS AND METHODS

Eight hundred and six men and women living in private households who were not on medication for nutritional disorders. Subjects were classified into four groups (Q1 to Q4), using cut-off points corresponding to quartiles of energy from NMES. Relationships were examined between dietary NMES concentration and intakes of calcium, iron, riboflavin, folate, vitamin C and vitamin D. Status indices were also assessed in each group.

RESULTS

Overall, a small proportion of men and women had intakes below the Lower Reference Nutrient Intake (LRNI) for calcium, iron, folate, riboflavin or vitamin C, while vitamin D intakes were universally low. Intakes of micronutrients tended to be highest at moderate levels of NMES in the diet (Q2 and Q3, equivalent to 8-15% of energy from NMES). Micronutrient status was low for riboflavin in 38% of the sample, while 15% had low vitamin C status and more than 10% were anaemic. There was little evidence that poorer nutrient status was associated with higher levels of dietary NMES. Although some indices of folate status were lower in Q4, this is most likely to reflect confounding by smoking. Energy intake accounted for 20-40% of the variance in micronutrient intakes, compared with less than 5% for NMES concentration.

CONCLUSIONS

A diet moderately high in NMES (up to around 15% of energy) is unlikely to have a detrimental impact on micronutrient intake or status in this age group. Energy intake is the major determinant of micronutrient adequacy.

[Effects of biologically active supplements on the antioxidant and vitamin status of patients with hypertension and ischemic heart disease]

Biologically active additives in integrated therapy of patients with cardiovascular diseases against a background body overweight. The influence of antiaterosclerotic diet with including some biologically active additives, which contain vitamins C, E, B2, B6, beta-carotene, Zn, Mg, Na, K, Ca, I was studied in 91 patients with ischemic heart disease, hypertension disease. The usage of biologically active additives during 4 weeks has promoted positive changes of clinical symptoms of diseases against a background of lowering of serum cholesterol, triglycerides and increasing of vitamins A, E, C, B2, B6.

Thiamine, riboflavin, pyridoxine, and vitamin C status in premature infants receiving parenteral and enteral nutrition

BACKGROUND

There is a paucity of data about water soluble vitamin status in low birthweight infants. Therefore, the authors' objective was to assess current feeding protocols.

METHODS

The authors measured serum concentrations for riboflavin, pyridoxine, and vitamin C and functional assays for thiamine and riboflavin longitudinally in 16 premature infants (birthweight, 1,336 +/- 351 g; gestational age, 30 +/- 2.5 weeks) before receiving nutrition (time 1, 2 +/- 1 days), during supplemental or parenteral nutrition (time 2, 16 +/- 10 days) and while receiving full oral feedings (time 3, 32 +/- 15 days). In plasma, vitamin C was measured colorimetrically, and riboflavin and pyridoxine were measured using high-performance liquid chromatography. The erythrocyte transketolase test as a functional evaluation of thiamine and the erythrocyte glutathione reductase test for riboflavin were measured colorimetrically.

RESULTS

At time 1, nutrient intake of vitamins were negligible because infants were receiving intravenous glucose and electrolytes only. Intakes differed between time 2 and time 3 for thiamine (510 +/- 280 and 254 +/- 115 microg. kg-1. d-1, respectively), riboflavin (624 +/- 305 and 371 +/- 193 microg. kg-1. d-1, respectively), and pyridoxine (394 +/- 243 and 173 +/- 85 microg/100 kcal, respectively), but not for vitamin C (32 +/- 17 and 28 +/- 12 mg. kg-1. d-1, respectively). Blood levels at times 1, 2, and 3 were for thiamine (4.9 +/- 2.7%, 3.3 +/- 6.6%, and 4.1 +/- 9% erythrocyte transketolase test, respectively), riboflavin (0.91 +/- 0.31, 0.7 +/- 0.3, 0.91 +/- 0.18 erythrocyte glutathione reductase test, respectively), riboflavin (19.5 +/- 17, 23.3 +/- 8.6, 17.6 +/- 10 ng/mL, respectively), pyridoxine (32 +/- 25, 40 +/- 16, 37 +/- 26 ng/mL, respectively), and vitamin C (5.2 +/- 3, 5 +/- 2.2, 10 +/- 5 microg/mL, respectively) and did not differ at those times.

CONCLUSIONS

Current intakes of these vitamins, except for possibly vitamin C, during parenteral and enteral nutrition seem to result in adequate plasma concentrations and normal functional indices.

[Dietary and biochemical riboflavin status in a cohort of young people in the community of Madrid]

Riboflavin status was measured in 228 young people (101 women and 127 men) between 18 and 35 years of age, resident in the Comunidad Autónoma de Madrid. A dietetic study was undertaken using a three day food record (which included one non-working day). Also, biochemical levels of riboflavin were investigated via the determination of the activation coefficient of erythrocyte glutathione reductase (alpha-EGR). Although the mean intake of riboflavin was acceptable (107.1 +/- 29.1 of recommended intakes), 46.9 of subjects showed intakes below recommended. At the biochemical level, 14.9% of subjects showed a moderate risk of vitamin B2 deficiency (alpha-EGR: 1.2-1.4) whilst 1.3% were at high risk (alpha-EGR > 1.4). Male subjects showed higher alpha-EGR levels than did females, which coincides with their greater intake of vitamin B2. Milk products provided some 40.4% of the vitamin, meats 19.9%, cereals 8%, vegetables 7.2%, eggs 6.3%. Other foods provided lesser amounts. Therefore, although riboflavin is available across the food groups, it Would seem that milk products are its most important source. Indeed, subjects with high milk product intakes (more than one ration per day) showed the highest riboflavin levels and the most adequate alpha-EGR levels. This study shows that riboflavin status can be improved, especially amongst those with low milk product intakes. An increase in the consumption of these foods to recommended levels (2-3 rations per day) might improve this situation at both dietetic and biochemical levels.

Low-dose vitamin B-6 effectively lowers fasting plasma homocysteine in healthy elderly persons who are folate and riboflavin replete

BACKGROUND

Current data suggest that physiologic doses of vitamin B-6 have no significant homocysteine-lowering effect. It is possible that an effect of vitamin B-6 was missed in previous trials because of a much greater effect of folic acid, vitamin B-12, or both.

OBJECTIVE

The aim of this study was to investigate the effect of low-dose vitamin B-6 supplementation on fasting total homocysteine (tHcy) concentrations in healthy elderly persons who were made replete with folate and riboflavin.

DESIGN

Twenty-two healthy elderly persons aged 63-80 y were supplemented with a low dose of vitamin B-6 (1.6 mg/d) for 12 wk in a randomized, double-blind, placebo-controlled trial after repletion with folic acid (400 microg/d for 6 wk) and riboflavin (1.6 mg/d for 18 wk); none of the subjects had a vitamin B-12 deficiency.

RESULTS

Folic acid supplementation lowered fasting tHcy by 19.6% (P < 0.001). After folic acid supplementation, baseline tHcy concentrations ranged from 6.22 to 23.52 micromol/L and 10 subjects had suboptimal vitamin B-6 status (plasma pyridoxal-P < 20 nmol/L). Two-way analysis of variance showed that the significant improvement in vitamin B-6 status in response to vitamin B-6 supplementation (on the basis of both pyridoxal-P: and the erythrocyte aspartate aminotransferase activation coefficient) was reflected in a significant reduction in plasma tHcy of 7.5%.

CONCLUSIONS

Low-dose vitamin B-6 effectively lowers fasting plasma tHcy in healthy subjects who are both folate and riboflavin replete. This suggests that any program aimed at the treatment or prevention of hyperhomocysteinemia should include vitamin B-6 supplementation.

Serum levels assessment of vitamin A, E, C, B2 and carotenoids in malnourished and non-malnourished hospitalized elderly patients

AIMS & METHODS

Serum levels of vitamins A, E, C, B2 and carotenoids were determined in protein-energy malnourished (PEM, with body mass index, BMI<18.5 kg/m2) and non-PEM (BMI+/-18.5 kg/m2) hospitalized elderly (age > or = 65 years) patients, in the University Hospital of Faculty of Medicine of Ribeirão Preto, São Paulo University.

RESULTS

PEM (n=21) and non-PEM (n=106) patients were paired for age (73.6+/-7.3 vs. 71.6+/-5.6 years) and male percentage (65.1 vs. 52.4%). As expected, PEM elderly showed lower (P<0.05) body weight (median 43.1; range: 29.9-51.4 vs. 58.1; range: 45.7-143.5 kg), triceps skinfold (5.2+/-3.1 vs. 10.1+/-4.9 mm), and mid-arm muscle circumference (20.3+/-2.5 vs. 23.1+/-3.4 cm). Serum albumin (4.0+/-0.9 vs. 4.1+/-0.7 g/dl) and total lymphocytes count (1918.3+/-919 vs. 1842.7+/-862 mm(3)) were similar, respectively, among PEM and non-PEM patients. The percentage of biochemical riboflavin deficiency (58.8 vs. 56.2), low serum levels of vitamin A (28.6 vs. 29.6) and vitamin E (18.7 vs. 25) were similar, respectively, between PEM and non-PEM groups. The prevalence of low serum levels of water soluble vitamins was higher (P<0.01) in malnourished elderly than in the non-PEM group (ascorbic acid, 80.9 vs. 56.7%, and carotenoids, 14.3 vs. 3%, respectively).

CONCLUSIONS

These results suggest that hospitalized malnourished elderly show high percentage of low water soluble vitamin serum levels, a phenomenon possibly linked to decreased food intake, especially fruits and vegetables.

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.

[Effects of biologically active food additives with different contents of vitamins on the vitamin status in humans]

The comparative study of influence of two biologically active food additives with the different contents of vitamins is carried out: a drink "Zolotoi Shar", the dose of vitamins in which makes 50-90% from recommended daily consumption, and "Vitabalance 2000", the contents of vitamins in which at 2-17 of time exceeds need of organism. The use of both additives within 3 weeks resulted in increase of levels of vitamins C, A, E, B2, B6 and carotenoids in blood serum. However if in case of consumption of a drink an authentic level was reached only for vitamin C and beta-carotene, in a case "Vitabalance 2000" for all investigated vitamins except vitamin A. Thus, if the consumption of a drink has lowered frequency of deficiency of 3-4 vitamins, but has not allowed to liquidate it completely, in case of "Vitabalance 2000" consumption the simultaneous deficiency 3-4 vitamins. The received data allow to believe the biologically active food additives containing vitamins in amounts exceeding recommended consumption, are convenient for fast liquidation of hypovitaminoses, and the preparations containing vitamins in doses making 30-50% from need of organism, are acceptable for daily filling of insufficient consumption of vitamins with a usual diet for a long time.

Water-soluble vitamin levels in patients undergoing high-flux hemodialysis and receiving long-term oral postdialysis vitamin supplementation

The prescription of multivitamin supplements for dialysis patients is routine practice, but the doses prescribed differ greatly from one dialysis center to another. Few data are available concerning long-term vitamin supplementation and its effects on patients either on high-flux hemodialysis or receiving postdialysis supplementation. For several years, we have systematically prescribed to our patients an oral postdialysis multivitamin supplement containing thiamine hydrochloride 100 mg, riboflavin 20 mg, pyridoxine hydrochloride 50 mg, folic acid 6 mg, and ascorbic acid 500 mg. The aim of this study was to perform a cross-sectional long-term evaluation of the vitamin levels in patients who received this vitamin supplement for at least 12 months. We also were interested in investigating the plasma oxalic acid and total homocysteine levels associated with the long-term prescription of these vitamin supplements. Thirty-three patients on high-flux dialysis were studied. Vitamin levels and/or vitamin-dependent enzymatic activities were within the normal range (N) in all patients. The mean results (+/-SD) were plasma ascorbic acid 13.6 +/- 6.4 mg/L (N > 4), plasma folate 14.1 +/- 1.1 microg/L (N > 3), for vitamin B1, alpha-ETK 1.02 +/- 0.02 (N < 1.18) and ETKo 100 +/- 13 U/L (N > 70), for vitamin B2, alpha-EGR 1.00 +/- 0.07 (N < 1.52) and EGRo 1282 +/- 213 U/L (N > 672), and for vitamin B6, alpha-EGOT 1.34 +/- 0.10 (N < 1.8) and EGOTo 380 +/- 84 U/L (N > 228). Plasma oxalic acid was higher than normal in all patients (mean = 61 +/- 15 micromol/L, N < 33). However, all patients had oxalic acid levels within the range reported in the literature for patients not taking extra ascorbic acid. Mean total homocysteine was 24 +/- 8 micromol/L with only 4 patients (12%) having normal levels (N < 15). In conclusion, the postdialysis supplement given provides adequate vitamin levels in almost all patients in the long term. Postdialysis prescription allows an optimal compliance with the treatment, is well accepted by the patients, and is cost-effective.

Riboflavin as a determinant of plasma total homocysteine: effect modification by the methylenetetrahydrofolate reductase C677T polymorphism

BACKGROUND

Plasma total homocysteine (tHcy) is a risk factor for cardiovascular disease. tHcy concentrations are partly determined by folate, cobalamin, and vitamin B(6) status, and methylenetetrahydrofolate reductase (MTHFR) and other flavoenzymes are important for the biotransformation of these vitamins. This motivates the investigation of the possible relationship between riboflavin status and tHcy.

METHODS

The study had a cross-sectional design and included 423 healthy blood donors, ages 19-69 years. We determined plasma tHcy, serum folate, serum cobalamin, serum creatinine, and MTHFR C677T genotype. In addition, we measured riboflavin and its two coenzyme forms, flavin mononucleotide and flavin adenine dinucleotide, in EDTA plasma by capillary electrophoresis and laser-induced fluorescence detection.

RESULTS

Riboflavin determined tHcy independently in a multiple linear regression model with adjustment for sex, age, folate, cobalamin, creatinine, and MTHFR genotype (P = 0.008). tHcy was 1.4 micromol/L higher in the lowest compared with the highest riboflavin quartile. The riboflavin-tHcy relationship was modified by genotype (P = 0.004) and was essentially confined to subjects with the C677T transition of the MTHFR gene.

CONCLUSIONS

Plasma riboflavin is an independent determinant of plasma tHcy. Studies on deficient populations are needed to evaluate the utility of riboflavin supplementation in hyperhomocysteinemia.

Plasma and urine riboflavin during riboflavin-free nutrition in very-low-birth-weight infants

BACKGROUND

Very-low-birth-weight (VLBW; birth weight <1500 g) infants receive enteral and parenteral nutriture that provides greater daily riboflavin (vitamin B2) than does term infant nutriture, and elevated plasma riboflavin develops in these infants after birth. The purpose of this study was to measure plasma and urine riboflavin concentrations in VLBW infants during riboflavin-free nutrition. Our hypothesis was that elevated plasma riboflavin develops in VLBW infants because of high daily intake and immature renal riboflavin elimination.

METHODS

Eighteen clinically healthy VLBW infants received parenteral nutrition and preterm infant formula during the first postnatal month. On postnatal days 10 and 28, the infants received specially prepared riboflavin-free enteral and parenteral nutrition for the 24-hour study period. Serial collections of plasma were made at time 0 and at 12 and 24 hours. Urine was collected continuously for the 24-hour period in 4-hour aliquots. Samples were analyzed for riboflavin concentration.

RESULTS

During the 24-hour riboflavin-free study period on postnatal day 10, plasma riboflavin decreased 56% from 185 +/- 37 ng/mL (mean +/- SEM), and urine riboflavin decreased 75% from 3112 +/- 960 mg/mL. Similarly, on postnatal day 28, plasma riboflavin decreased 79% from 184 +/- 32 ng/mL, and urine riboflavin concentration decreased 91% from 5092 +/- 743 ng/mL during the 24-hour riboflavin-free study period. Riboflavin half-life (t(1/2)) was 18.5 hours on postnatal day 10 and decreased 48% by postnatal day 28. Riboflavin elimination was 145.1 +/- 20.6 mg/kg per day on postnatal day 10 and increased 40% by postnatal day 28.

CONCLUSION

The VLBW infants who received parenteral nutrition and preterm infant formula had elevated plasma riboflavin on postnatal days 10 and 28. Plasma riboflavin t(1,2) was shorter and renal riboflavin elimination was greater on postnatal day 28 than on postnatal day 10. Plasma riboflavin was normal after 24 hours of riboflavin-free nutrition. The pattern of plasma and urine riboflavin in VLBW infants suggests a lower daily intake would maintain plasma riboflavin close to normal.

Concentrations of riboflavin and related organic acids in children with protein-energy malnutrition

BACKGROUND

Riboflavin, flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD) concentrations have been little studied in cases of malnutrition.

OBJECTIVE

Our objective was to investigate the effects of malnutrition on riboflavin status and riboflavin's relation with thyroid hormones and concentrations of urinary organic acids.

DESIGN

Malnourished children from the savannah in Benin (group S, n = 30) and the coast in Togo (group C, n = 30), as well as 24 control subjects from both regions, were studied. Blood riboflavin, FMN, and FAD were analyzed by HPLC; urinary organic acids were analyzed by gas chromatography-mass spectrometry.

RESULTS

Children in group S were more severely malnourished than children in group C. Triiodothyronine concentrations were lower in group S than in group C or the control group (1.12 +/- 0.24 compared with 1.74 +/- 0.18 and 2.92 +/- 0.19 nmol/L, respectively; P < 0.0001). Plasma riboflavin concentrations in group S were higher than those in group C or the control group (66.90 +/- 12.75 compared with 28.09 +/- 9.12 and 20.08 +/- 3.03 nmol/L, respectively; P < 0.001). Plasma FAD concentrations in group S were lower than those in group C or the control group (31.57 +/- 10.19 compared with 59.02 +/- 5.60 and 65.35 +/- 5.23 nmol/L, respectively; P < 0.0001). Dicarboxylic aciduria was higher in group C than in group S or the control subjects.

CONCLUSIONS

Children in group S had low triiodothyronine concentrations and low conversion of plasma riboflavin into its cofactors, leading to a plasma FAD deficiency. Plasma FAD was not correlated with urinary dicarboxylic acid concentrations.

Changes in thiamin, riboflavin, niacin, beta-carotene, vitamins, C, A, D and E status of French Elderly Subjects during the first year of institutionalization

Vitamin status was assessed in 26 recently institutionalized elderly subjects by combining dietary and biochemical measurements of thiamin, riboflavin, niacin, beta-carotene, vitamins C, A, D and E at admission (P1), and 1.5 (P2), 3.0 (P3), 4.5 (P4), 6.0 (P5), 12 (P6) months later. At admission, except for vitamin A, mean vitamin intakes were lower than the 1992 French Recommended Dietary Allowance. Thiamin, vitamins C, A and E status seemed nearly satisfactory as less than one-fourth of the population sample had blood values lower than the cut-off point for thiamin (erythrocyte thiamin pyrophosphate < 0.17 mumol/l), vitamin A (serum retinol < 1.05 mumol/l), vitamin C (serum vitamin C < 11.3 mumol/l) and vitamin E (serum alpha-tocopherol < 9.3 mumol/l) or higher than the cut-off point for thiamin (erythrocyte transketolase activity coefficient > 1.19). Almost half of the subjects for riboflavin, and almost all non supplemented subjects for vitamin D were in risk of vitamin deficiency (46% had an erythrocyte glutathione reductase activity coefficient > 1.19 and 72% had a plasma 25(OH)D3 < 25 nmol/l). During the study, vitamins status remained unchanged for riboflavin, niacin, vitamins A, D and E, improved for vitamin C (P = 0.004) or impaired for thiamin (P = 0.008). Thus, institutionalization seemed to have no effect on riboflavin, niacin, vitamins A, D and E status and a slight effect on thiamin and vitamin C status.

Analysis of riboflavin and riboflavin cofactor levels in plasma by high-performance liquid chromatography

We describe an assay which determines simultaneously riboflavin (RF), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) in plasma, using galactoflavin (GF) as an internal standard. The flavins were extracted on a C18 Sep-Pack cartridge after protein precipitation with 10% trichloroacetic acid, and were analyzed on a C18 RP-HPLC with 85% phosphate-magnesium acetate buffer (pH 3.4) and 15% acetonitrile. FAD, FMN, GF and RF extraction recoveries were 101.0-5.6, 97.0-6.5, 97.0-2.0 and 95.0-4.1%, and reproducibilities were 5.9, 6.8, 2.1 and 4.3%, respectively. FAD, FMN and RF values in infant and adolescent plasma were in the range 53.5-108.2, 9.0-25.1 and 12.7-53.4 nM, and 36.5-157.20, 7.1-24.6 and 8.2-57.8 nM, respectively. Using GF as an internal standard improved the quantification of these B2 vitamers.

Predictors of micronutrient status among six- to twelve-month-old breast-fed Ghanaian infants

This study describes the factors associated with hemoglobin and plasma ferritin, zinc and retinol concentrations and erythrocyte riboflavin status among 208 Ghanaian infants who participated in a complementary feeding intervention trial from 6 to 12 mo of age. Anthropometric, morbidity and dietary data were collected regularly from 1 to 12 mo; blood samples were collected at 6 and 12 mo. The prevalence of low micronutrient status at 6 and 12 mo, respectively, was as follows: hemoglobin <100 g/L, 30 and 34%; plasma ferritin <12 microg/L, 17 and 43%; plasma zinc <10.7 micromol/L, 4 and 6%; plasma retinol <0.7 micromol/L, 26 and 26%; erythrocyte riboflavin <200 umol/L of packed red cells, 14 and 10%. Multiple regression was used to identify factors significantly associated with micronutrient status. From 6 to 12 mo, fever prevalence was associated with a decrease in hemoglobin, but an increase in erythrocyte riboflavin concentrations, and diarrhea prevalence was related to a decrease in plasma retinol. Seasonal differences were evident for most of the indicators of micronutrient status, and elevated C-reactive protein levels (indicative of recent infection) were related to lower hemoglobin, retinol and zinc concentrations but higher ferritin and erythrocyte riboflavin concentrations. Weight at birth or at 1 mo of age was positively related to iron, zinc and vitamin A status, but a more rapid weight gain was associated with depletion of iron stores. Socioeconomic status was related to higher hemoglobin, riboflavin and zinc concentrations. The feeding of a micronutrient-fortified food was positively associated with plasma ferritin and retinol concentrations at 12 mo. These results suggest that prenatal factors, socioeconomic status, dietary intake and morbidity all influence infant micronutrient status, and that fortification of complementary foods is one potential avenue for preventing deficiencies.

Predictors of growth from 1 to 18 months among breast-fed Ghanaian infants

OBJECTIVE

To examine factors associated with the physical growth of breast-fed Ghanaian infants during the first 18 months of life.

DESIGN

A community-based longitudinal study.

SETTING

The study was carried out in Techiman, a district capital and major food trading center in the Brong Ahafo region of Ghana.

SUBJECTS

One-month old infants (n=216) with birth weight >/= 2.5 kg were recruited from Maternal and Child Health Centers.

METHOD

From 6 to 12 months, infants were provided with one of four types of nutritionally enhanced complementary foods. Anthropometric assessments were completed monthly from 1 to 12 months and every other month from 12 to 18 months. Information was collected on household characteristics, morbidity from common infections and dietary intakes. Blood samples were collected at 6 and 12 months to assess iron, zinc, riboflavin and vitamin A status. Multiple regression analysis was used to examine factors associated with growth during the age intervals of 1-6, 4-6, 6-12 and 12-18 months as well as size attained at 12 and 18 months.

RESULTS

Prevalence of diarrhea and fever were negatively associated with growth during the first year of life. No significant relationship was found between respiratory illness (defined as cough or purulent nasal discharge) and growth. With the exception of dietary zinc intake, dietary variables were generally not significantly associated with growth. Maternal education was positively associated with growth during most of the age intervals.

CONCLUSION

These findings suggest that interventions to reduce morbidity and improve the education of girls may benefit children's growth in this population.

SPONSORSHIP

Nestle Foundation; Rockefeller Foundation African Dissertation Internship Award; Fulbright Scholarship. European Journal of Clinical Nutrition (2000) 54, 41-49

Tissue distribution and turnover of [3H]riboflavin during respiratory infection in mice

Studies in children and mice suggest that respiratory infections cause a mobilization of riboflavin from the tissues to the blood, resulting in increased urinary loss of this vitamin. To verify this observation, the tissue distribution and turnover of [3H]riboflavin were investigated in control and low-riboflavin-fed mice infected with Klebsiella pneumoniae. Infection significantly reduced [3H]riboflavin levels in the liver and kidney of low-riboflavin-fed mice and in the liver of control mice. Such changes were not observed in tissues such as muscle, small intestine, and brain. Urinary excretion of [3H]riboflavin increased significantly during the acute phase of infection and the biological half-life of [3H]riboflavin was shorter in the low-riboflavin-fed group. The results confirm that the mobilization of riboflavin from tissues to blood during infection results in a deterioration of riboflavin status. Thus, the study supports the hypothesis that respiratory infection is a nondietary factor contributing to the high prevalence of subclinical riboflavin deficiency in children of developing countries like India.

Riboflavin levels in maternal milk: the influence of vitamin B2 status during the third trimester of pregnancy

OBJECTIVE

The aim of the present investigation was to study the relationship between riboflavin status during the third trimester of pregnancy and levels of this vitamin in transition milk (days 13 to 14 of lactation) and mature milk (day 40 of lactation).

METHODS

The pregnancies and lactation periods of 57 healthy women between 18 and 35 years of age (27+/-3.7 years) were monitored, vitamin intake during the third trimester was determined by recording the consumption of foods over five days and by registering the quantities provided by dietary supplements. Riboflavin status during this stage of pregnancy was determined via the measurement of the activation of erythrocyte glutathione reductase (EGR) by flavine adenine dinucleotide (FAD). Milk riboflavin levels were determined by fluorometry.

RESULTS

Those subjects with riboflavin intakes below recommended (1.6 mg/day) (Group L) showed lower consumption of milk products (305.2+/-88.5 g/day) than did those with greater intakes (Group H) (507.9+/-137.2 g/day). The consumption of riboflavin containing supplements was very low and was seen only in two H subjects. Transition and mature milk riboflavin levels were significantly higher in H subjects (948.1+/-700.1 nmol/L for transition milk and 993.8+/-436.6 nmol/L for mature milk) than L subjects (574.9+/-258.7 nmol/L for transition milk and 725.4+/-254.3 nmol/L for mature milk). Subjects with alpha-EGR coefficients over 1.2 in the third trimester showed significantly lower mature milk riboflavin levels (704.1+/-241.8 nmol/L) than did subjects with more satisfactory alpha-EGR coefficients (996.4+/-302.9 nmol/L).

CONCLUSION

The influence of maternal vitamin B2 status during pregnancy on breast milk riboflavin levels was confirmed.

Quantification of riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma by capillary electrophoresis and laser-induced fluorescence detection

BACKGROUND

Riboflavin is the precursor of flavin mononucleotide (FMN) and FAD, which serve as cofactors for several redox enzymes. We have developed a capillary electrophoresis method for the determination of riboflavin and its two coenzyme forms in human plasma.

METHODS

Trichloroacetic acid-treated plasma was subjected to solid-phase extraction on reversed-phase columns. The analytes were separated by micellar electrokinetic capillary chromatography in uncoated fused- silica capillaries filled with borate buffer containing 50 mmol/L sodium dodecyl sulfate, methanol, and N-methylformamide. Native fluorescence was monitored at 530 nm, using an argon laser operating at 488 nm as excitation source.

RESULTS

The assay was linear over a concentration range of two orders of magnitude, and the limit of detection was far below physiological concentrations for all vitamers. The within-day and between-day coefficients of variation were 4-9% and 6-12%, respectively. The reference values (median, 5-95 percentiles) obtained by analyzing plasma from 63 healthy subjects were 8.6 nmol/L (2.7-42.5 nmol/L) for riboflavin, 7.0 nmol/L (3.5-13.3 nmol/L) for FMN, and 57.9 nmol/L (44.5-78.1 nmol/L) for FAD.

CONCLUSIONS

Capillary electrophoresis with laser-induced fluorescence detection allows determination of all riboflavin vitamers far below physiological concentrations. The method may become a useful tool for the assessment of riboflavin status in humans.

The thiamin, riboflavin and pyridoxine status of patients on emergency admission to hospital

The aim of this study was to assess the prevalence of thiamin, riboflavin and pyridoxine deficiencies at admission to an acute hospital. One hundred and twenty adult patients were selected at random from those admitted via the Accident and Emergency department over 3 days. Comparisons were made with a group of 80 healthy blood donors sequentially attending a local transfusion centre. The alcohol intake of 500 patients admitted sequentially via the same Accident and Emergency department was also assessed. Erythrocyte transketolase (ETK), glutathione reductase (EGR) and aspartate aminotransferase (EAA) coenzyme activation assays were used to determine thiamin, riboflavin and pyridoxine deficiencies. The prevalences of deficiency states in the inpatient group were 21, 2.7 and 32% for thiamin, riboflavin and pyridoxine deficiencies respectively with 49.2% being deficient in one or more vitamin. The mean alcohol intake in the group of patients in whom this was assessed was 9.7 units per week compared with 10 units per week amongst blood donors.

Riboflavin and riboflavin-derived cofactors in adolescent girls with anorexia nervosa

BACKGROUND

Thyroid hormones, riboflavin, riboflavin cofactors, and organic acids were assessed in girls with anorexia nervosa.

OBJECTIVE

The objective was to examine the effect of malnutrition and low thyroid hormone concentrations on erythrocyte and plasma riboflavin metabolism and their relation with urinary organic acid excretion.

DESIGN

Seventeen adolescent girls with anorexia nervosa [body mass index (BMI; in kg/m2): 14.8 +/- 2.2] and 17 age-matched, healthy girls (control subjects; BMI: 20.5 +/- 2.2) took part in the feeding study. Erythrocyte and plasma riboflavin as well as riboflavin cofactors (flavin mononucleotide and flavin adenine dinucleotide) were assessed by HPLC, whereas urinary organic acids were assessed by gas chromatography-mass spectrometry.

RESULTS

Anorectic patients who began a feeding program had higher erythrocyte riboflavin (3.5 +/- 2.2 compared with <0.1 nmol/mol hemoglobin; P < 0.001), lower plasma flavin adenine dinucleotide (57.8 +/- 18.5 compared with 78.5 +/- 54.3 nmol/L; P < 0.05), and higher urinary ethylmalonic acid (7.12 +/- 4.39 compared with 1.3 +/- 2.8 micromol/mmol creatinine; P < 0.001) and isovalerylglycine (7.65 +/- 4.78 compared with 3.8 +/- 0.9 micromol/mmol creatinine; P < 0.05) concentrations than did control subjects. Triiodothyronine concentrations were low and negatively correlated with plasma riboflavin concentrations (r = -0.69, P < 0.01). Not all patients showed improvements in these biochemical indexes after 30 d of refeeding.

CONCLUSIONS

The low triiodothyronine concentrations observed in anorexia nervosa could alter the extent of riboflavin conversion into cofactors, thus leading to high erythrocyte riboflavin concentrations, low plasma flavin adenine dinucleotide concentrations, and high rates of ethylmalonic acid and isovalerylglycine excretion.