Assessment of thiamin (vitamin B1) and riboflavin (vitamin B2) status in an adult Mediterranean population

Investigation of Whole Blood Thiamine Concentration in Independently Ambulatory Residents of a Provincial Town in Japan: A Cross-Sectional Study

Background Thiamine deficiency (TD) is an important public health problem in nutrition, occurring in 2-6% of the population in Europe and the US, whereas thiamine levels are reported to be significantly reduced by 36.6-40% in some populations of East Asia. However, there is little information available at present, regarding factors such as age, despite the continued aging of society. Further, studies such as those mentioned above have not yet been undertaken in Japan, the country in which population aging is most advanced. Objective To investigate TD in the Japanese community-dwelling individuals who are independently ambulatory. Methods We undertook an examination of TD in blood samples obtained from 270 citizens in a provincial town, aged 25-97 years, who were able to walk to the venue and provide informed consent for inclusion in this research and of whom 8.9% had a history of cancer. We summarized the demographic characteristics of the subjects. The whole-blood thiamine concentrations were measured using the high-performance liquid chromatography method. A value of 21.3 ng/ml or less was taken as low and a borderline value was set as less than 28 ng/ml. Results The mean (±SD) whole blood thiamine concentration was 47.6 ± 8.7 ng/ml. No TD was observed to exist participating in this study, with no subjects even showing show borderline values. Further, there was no significant difference in thiamine level between those aged 65 or older and those aged less than 65. Conclusions No cases of TD were observed among the subjects in this study, nor was the concentration of thiamine found to be related to age. It is possible that the frequency of TD might be very low in citizens who have a certain level of activity. In the future, it is necessary to expand the prevalence of TD to a wider range of subjects.

Water-Soluble Vitamins Status in Patients Undergoing Maintenance Hemodialysis

The concentration of water-soluble vitamins (except folic acid and vitamin B12) is not routinely measured, which may lead to undiagnosed deficiencies among hemodialysis (HD) patients. The aim of the study was to assess the blood concentration of water-soluble vitamins in HD patients in comparison with healthy subjects and to assess the impact of diabetes mellitus (DM) coexistence on the concentration of these vitamins. The two-center study included 142 HD patients and a control group of 31 healthy subjects. Vitamins concentration was determined using high-performance liquid chromatography (HPLC). Vitamin B1, B6, and B12 levels were significantly lower in the HD group than in the control group (p < 0.001). Vitamin B1 and B2 were negatively correlated with blood urea nitrogen (BUN) levels before HD (R = −0.39, R = −0.38; p < 0.05). Vitamin B3, B12, and C were positively correlated with the albumin concentration (R = 0.26, R = 0.27, R = 0.28; p < 0.05). Among diabetic patients, only the concentration of vitamin B1 was lower than among non-diabetic patients. The concentration of water-soluble vitamins may be related to the adequacy of dialysis, the time of laboratory determination since the last dialysis, diet, coexistence of other diseases, use of drugs, and dietary supplements in individual patients.

Riboflavin intake and status and relationship to anemia

Riboflavin in its coenzyme forms, flavin mononucleotide and flavin adenine dinucleotide, is essential for multiple redox reactions necessary for energy production, antioxidant protection, and metabolism of other B vitamins, such as niacin, pyridoxine, and folate. Erythrocyte glutathione reductase activity coefficient (EGRac) is a biomarker of riboflavin status; ratios ≥1.40 are commonly interpreted as indicating biochemical deficiency. Most research on riboflavin status comes from low-income countries and rural settings, which reported high rates of riboflavin deficiency and inadequate intake. However, some studies suggest that riboflavin deficiency, based on the functional indicator EGRac, is also of concern in middle- and high-income countries. Biochemical riboflavin deficiency that does not cause clinical symptoms may contribute to anemia, particularly among women and children. Riboflavin enhances iron absorption, and riboflavin deficiency decreases iron mobilization from stores. The current knowledge on riboflavin's role in metabolic processes and its biochemical status is summarized in this review, and the available evidence on the role of riboflavin in anemia among different populations is discussed.

The Effect of a Single Bout of Exercise on Vitamin B2 Status Is Not Different between High- and Low-Fit Females

High-fitness individuals have been suggested to be at risk of a poor vitamin B2 (riboflavin) status due to a potentially higher vitamin B2 demand, as measured by the erythrocyte glutathione reductase (EGR) activation coefficient (EGRAC). Longer-term exercise interventions have been shown to result in a lower vitamin B2 status, but studies are contradictory. Short-term exercise effects potentially contribute to discrepancies between studies but have only been tested in limited study populations. This study investigated if vitamin B2 status, measured by EGRAC, is affected by a single exercise bout in females who differ in fitness levels, and that represents long-term physical activity. At baseline and overnight after a 60-min cycling bout at 70% V·O₂peak, EGR activity and EGRAC were measured in 31 young female adults, divided into a high-fit (V·O₂peak ≥ 47 mL/kg/min, N = 15) and low-fit (V·O₂peak ≤ 37 mL/kg/min, N = 16) group. A single exercise bout significantly increased EGR activity in high-fit and low-fit females (P_time = 0.006). This response was not affected by fitness level (P_time*group = 0.256). The effect of exercise on EGRAC was not significant (P_time = 0.079) and not influenced by EGR activity. The exercise response of EGRAC was not significantly different between high-fit and low-fit females (P_time*group = 0.141). Thus, a single exercise bout increased EGR activity, but did not affect EGRAC, indicating that vitamin B2 status was not affected. The exercise response on EGRAC and EGR did not differ between high-fit and low-fit females.

Probiotic Potential of a Novel Vitamin B2-Overproducing Lactobacillus plantarum Strain, HY7715, Isolated from Kimchi

Vitamin B2, also known as riboflavin, is essential for maintaining human health. The purpose of this study was to isolate novel lactic acid bacteria that overproduce vitamin B2 and to validate their potential as probiotics. In this study, Lactobacillus plantarum HY7715 (HY7715) was selected among lactic acid bacteria isolated from Kimchi. HY7715 showed a very high riboflavin-producing ability compared to the control strain due to the high expression of ribA, ribB, ribC, ribH, and ribG genes. HY7715 produced 34.5 ± 2.41 mg/L of riboflavin for 24 h without consuming riboflavin in the medium under optimal growth conditions. It was able to produce riboflavin in an in vitro model of the intestinal environment. In addition, when riboflavin deficiency was induced in mice through nutritional restriction, higher levels of riboflavin were detected in plasma and urine in the HY7715 administration group than in the control group. HY7715 showed high survival rate in simulated gastrointestinal conditions and had antibiotic resistance below the cutoff MIC value suggested by the European Food Safety Authority; moreover, it did not cause hemolysis. In conclusion, HY7715 could be considered a beneficial probiotic strain for human and animal applications, suggesting that it could be a new alternative to address riboflavin deficiency.

Dietary Riboflavin Intake and Riboflavin Status in Young Adult Women Living in Metro Vancouver, Canada

BACKGROUND

Nutrition surveys suggest that <10% of Canadian adults have inadequate riboflavin intakes. However, biochemical riboflavin deficiency [erythrocyte glutathione reductase activity coefficient (EGRac) ≥1.40] has been reported in 41% of young adult women living in Metro Vancouver. Canadian Chinese ethnicity comprise >25% of Vancouver's population and are postulated to have poorer riboflavin status than those of European ethnicity because they could be less likely to consume dairy products and fortified wheat.

OBJECTIVES

The objectives of this study were to determine dietary riboflavin intake and food sources, and to assess the association between riboflavin intake and status in young women of European (n = 107) and Chinese (n = 91) ethnicities living in Metro Vancouver, Canada.

METHODS

This was a cross-sectional study conducted in women (aged 19-45 y). Women were healthy, not pregnant or breastfeeding, of European or Chinese ethnicities, and not taking riboflavin-containing supplements for the past 4 mo. Dietary riboflavin intake was assessed using the past-year Diet History Questionnaire II, and riboflavin status (EGRac) was measured in fasting venous blood samples.

RESULTS

Only 7% of participants had dietary riboflavin intakes below the Estimated Average Requirement (0.9 mg/d), but 40% of women had biochemical riboflavin deficiency (EGRac ≥1.40). Although more Canadian women of European ethnicity than Chinese ethnicity had biochemical riboflavin deficiency (46% and 34%; P < 0.001), median dietary riboflavin intake did not differ (1.73 and 1.82 mg/d; P = 0.587). Dairy products and vegetables contributed the most to riboflavin intake. Energy-adjusted dietary riboflavin intake was inversely associated with EGRac (B = -0.04, 95% CI: -0.07, -0.01). However, after further adjustment the relation was not significant.

CONCLUSIONS

Overall, women of reproductive age living in Metro Vancouver, Canada, had a low prevalence of inadequate dietary riboflavin intake despite the high prevalence of apparent biochemical riboflavin deficiency.

Dietary riboflavin deficiency induces ariboflavinosis and esophageal epithelial atrophy in association with modification of gut microbiota in rats

PURPOSE

Riboflavin deficiency causes ariboflavinosis, a common nutritional deficiency disease. The purpose of this study is to investigate the effects of riboflavin deficiency on the important internal organs and its potential mechanisms.

METHODS

Experiment 1, male F344 rats were randomly assigned to R₆ (normal riboflavin, 6 mg/kg) and R₀ (riboflavin-deficient, 0 mg/kg) groups. Experiment 2 rats were assigned to R₆, R_0.6 (0.6 mg/kg) and R_0.06 (0.06 mg/kg) groups. Experiment 3 rats were assigned to R₆ and R₀ → R₆ (riboflavin replenishment) groups. Bacterial communities were analyzed based on 16S rRNA gene sequencing.

RESULTS

Riboflavin deficiency induced ariboflavinosis (R_0.06 46.7%; R₀ 72%) and esophageal epithelial atrophy (R_0.06 40%; R₀ 44%) in rats, while the R₆ group did not display symptoms (P < 0.001, respectively). Esophageal epithelial atrophy occurred simultaneously (R_0.06 66.7%; R₀ 63.6%) with ariboflavinosis or appeared alone (R_0.06 33.3%; R₀ 36.4%). Esophagus is the most vulnerable internal organ. Riboflavin deficiency followed by replenishment (R₀ → R₆) was effective in treating ariboflavinosis (83.3% vs. 0%, P < 0.001) and esophageal epithelial atrophy (66.7% vs. 20%, P = 0.17). Riboflavin deficiency modulated gut microbiota composition. The several key genera (Romboutsia, Turicibacter and Clostridium sensu stricto 1) were strongly correlated with ariboflavinosis and esophageal epithelial atrophy (P < 0.01 or P < 0.05). The potential mechanism is that gut microbiota affects body's xenobiotic biodegradation and metabolism, and genomic instability.

CONCLUSIONS

Riboflavin deficiency induces ariboflavinosis and esophageal epithelial atrophy by modulating the gut microbiota, and offers new Queryinsight into riboflavin deficiency and esophageal lesions.

Suboptimal Biochemical Riboflavin Status Is Associated with Lower Hemoglobin and Higher Rates of Anemia in a Sample of Canadian and Malaysian Women of Reproductive Age

BACKGROUND

Riboflavin is required for several redox reactions. Clinical riboflavin deficiency occurs mainly in low-income countries, where it is associated with anemia. The functional significance of suboptimal riboflavin status in different populations and its role in anemia is not well understood.

OBJECTIVES

We assessed the biomarker status of riboflavin and its association with hemoglobin concentration and anemia in women living in Vancouver, Canada, and Kuala Lumpur, Malaysia.

METHODS

Healthy nonpregnant, nonbreastfeeding women (19-45 y) were recruited from Canada ( n = 206) and Malaysia (n = 210) via convenience sampling. Fasting blood was collected to assess riboflavin status [erythrocyte glutathione reductase activity coefficient (EGRac)], hematological indicators, soluble transferrin receptor (sTfR), ferritin, vitamin A, folate, and vitamin B-12 concentrations. Linear and logistic regression models were used to assess the association of riboflavin status with hemoglobin concentration and anemia.

RESULTS

EGRac (mean ± SD) values were higher, indicating poorer riboflavin status, in Malaysian compared with Canadian women (1.49 ± 0.17 compared with 1.38 ± 0.11). Likewise, riboflavin biomarker deficiency (EGRac ≥1.40) was significantly more prevalent among Malaysians than Canadians (71% compared with 40%). More Malaysian than Canadian women were anemic (hemoglobin <120 g/L; 18% compared with 7%). With use of linear regression (pooled sample; n = 416), EGRac values were negatively associated with hemoglobin concentration (r = -0.18; P < 0.001). This relation remained significant (P = 0.029) after adjusting for age, parity, ethnicity, vitamin B-12, folate, sTfR, ferritin, and vitamin A. Women with riboflavin deficiency (EGRac ≥1.40) were twice as likely to present with anemia (adjusted OR: 2.38; 95% CI: 1.08, 5.27) compared with women with EGRac <1.40.

CONCLUSIONS

Biochemical riboflavin deficiency was observed in Canadian and Malaysian women, with higher rates of deficiency among Malaysian women. Deficient biomarker status of riboflavin was a weak but significant predictor of hemoglobin and anemia, suggesting that the correction of riboflavin deficiency may potentially play a small protective role in anemia, but this requires further investigation.

Prevalent Low Thiamine Status Among Adults Living in Seoul Metropolitan Area (South Korea)

The thiamine status of South Korean people has not been recently reported. Therefore, the aim of this study was to determine thiamine intake and status of Korean adults based on a biochemical index. Three consecutive 24-h food recalls and morning first-urine samples were obtained from 143 healthy adults (65 men and 78 women), aged 20-64 years, living in Seoul metropolitan area, Korea. Daily dietary thiamine intake of men and women was 1.42 ± 0.37 mg and 1.18 ± 0.24 mg, respectively. Only 9.1% of the subjects consumed less total thiamine (dietary plus supplemental thiamine) than the estimated average requirement for Koreans. The top 10 major dietary thiamine sources were pork, polished rice, ramyeon (Korean instant noodles), baechukimchi (Chinese cabbage), mandarin oranges, chicken, cow's milk, bread, beef, and potatoes. Those top 10 foods provided 57.85% of the subjects' dietary thiamine intake and the top 30 food sources provided 77.23% of their dietary thiamine intake. Urinary thiamine excretions for men and women were 37.20 ± 26.54 and 39.09 ± 28.80 μg/g creatinine, respectively. Urinary thiamine excretion was positively correlated with total thiamine intake (r = 0.3349, p < 0.0001). Approximately 40% of the subjects had urinary thiamine excretion < 27 μg/g creatinine, indicating thiamine deficiency. In conclusion, thiamine intake among Korean adults in this study was generally adequate, but there was a high prevalence of a low thiamine status. Further study is required to explain the incongruity of adequate intake and low thiamine status thiamine in the South Korean population.

Riboflavin status, MTHFR genotype and blood pressure: current evidence and implications for personalised nutrition

Clinical deficiency of the B-vitamin riboflavin (vitamin B2) is largely confined to developing countries; however accumulating evidence indicates that suboptimal riboflavin status is a widespread problem across the developed world. Few international data are available on riboflavin status as measured by the functional biomarker, erythrocyte glutathione reductase activation coefficient, considered to be the gold standard index. One important role of riboflavin in the form of flavin dinucleotide is as a co-factor for the folate-metabolising enzyme methylenetetrahydrofolate reductase (MTHFR). Homozygosity for the common C677T polymorphism in MTHFR, affecting over 10 % of the UK and Irish populations and up to 32 % of other populations worldwide, has been associated with an increased risk of CVD, and more recently with hypertension. This review will explore available studies reporting riboflavin status worldwide, the interaction of riboflavin with the MTHFR C677T polymorphism and the potential role of riboflavin in personalised nutrition. Evidence is accumulating for a novel role of riboflavin as an important modulator of blood pressure (BP) specifically in individuals with the MTHFR 677TT genotype, with results from a number of recent randomised controlled trials demonstrating that riboflavin supplementation can significantly reduce systolic BP by 5-13 mmHg in these genetically at risk adults. Studies are however required to investigate the BP-lowering effect of riboflavin in different populations and in response to doses higher than 1·6 mg/d. Furthermore, work focusing on the translation of this research to health professionals and patients is also required.

Plasma riboflavin is a useful marker for studying riboflavin requirement in Chinese male adults

Urinary riboflavin excretion and erythrocyte glutathione reductase activation coefficient are frequently applied in determining riboflavin requirement. Previously, we found that plasma riboflavin is a sensitive marker in the assessment of riboflavin status in rat models. Here, we hypothesize that plasma riboflavin is a useful maker in studying riboflavin requirement. This study examines the changes of fasting plasma riboflavin and urinary riboflavin excretion in response to different riboflavin intake levels in Chinese male adults. The estimated average requirement (EAR) of riboflavin was extrapolated. Seventy-eight participants were randomly divided into the control and 5 riboflavin-supplemented groups. A 6-week riboflavin supplementation was performed at the doses of 0, 0.2, 0.4, 0.6, 0.8, or 1.0 mg daily. The energy expenditure was 15.4 ± 1.9 MJ/d, as estimated by the 24-hour physical activity recording method. Dietary riboflavin intake was 1.0 ± 0.2 mg/d, based on chemical analysis. The fasting plasma riboflavin was increased significantly in a dose-dependent manner when the supplemented riboflavin exceeded 0.4 mg/d and the EAR of riboflavin was suggested to be between 1.3 and 1.5 mg/d. In addition, we found a significant increase in fasting urinary riboflavin excretion when the supplemented riboflavin exceeded 0.6 mg/d. The critical point was calculated as 1.4 mg/d, based on the intersecting point of the 2 regression lines at lower and higher riboflavin intakes. These findings demonstrate that plasma riboflavin is a sensitive marker for riboflavin status, and the EAR of riboflavin for Chinese male adults is 1.4 mg.

Poor thiamin and riboflavin status is common among women of childbearing age in rural and urban Cambodia

BACKGROUND

Thiamin deficiency in infancy is the underlying cause of beriberi, which can be fatal without rapid treatment. Reports of thiamin deficiency are common in Cambodia; however, population representative data are unavailable. Because B-complex vitamin deficiencies commonly occur in combination, riboflavin was also investigated.

OBJECTIVE

We determined the biomarker status of thiamin and riboflavin in women of childbearing age in rural and urban Cambodia.

METHODS

We measured thiamin (erythrocyte thiamin diphosphate; TDP) and riboflavin (erythrocyte glutathione reductase activity coefficient; EGRac) status in a representative sample of Cambodian women (aged 20-45 y) in urban Phnom Penh (n = 146) and rural Prey Veng (n = 156), Cambodia, and, for comparison purposes, in a convenience sample of women in urban Vancouver, British Columbia, Canada (n = 49).

RESULTS

Thiamin insufficiency (TDP ≤ 90 nmol/L) was common among both urban (39%) and rural (59%) Cambodian women (P < 0.001), whereas <20% of Vancouver women were thiamin insufficient (P < 0.001). The prevalence of suboptimal and deficient riboflavin status (EGRac ≥ 1.3) was 89%, 92%, and 70% among women in Phnom Penh, Prey Veng, and Vancouver, respectively (P < 0.001).

CONCLUSIONS

Suboptimal status of both thiamin and riboflavin were common in Cambodian women, with substantially higher rates among women living in rural Prey Veng than in urban Phnom Penh. Strategies may be needed to improve the thiamin and riboflavin status of women in Cambodia. The unexpected finding of high riboflavin inadequacy status in Vancouver women warrants further investigation.

Evaluation of riboflavin intakes and status of 20-64-year-old adults in South Korea

A recent Korea National Health and Nutrition Survey indicated inadequate riboflavin intake in Koreans, but there is limited research regarding riboflavin status in South Korea. The purpose of this study was to determine riboflavin intake and status of Korean adults. Three consecutive 24-h food recalls were collected from 412 (145 men and 267 women) healthy adults, aged 20–64 years, living in South Korea and urine samples were collected from 149 subjects of all subjects. The dietary and total (dietary plus supplemental) riboflavin intake was 1.33 ± 0.34 and 2.87 ± 6.29 mg/day, respectively. Approximately 28% of the subjects consumed total riboflavin less than the Estimated Average Requirement. Urinary riboflavin excretion was 205.1 ± 190.1 μg/g creatinine. Total riboflavin intake was significantly positively correlated to the urinary riboflavin excretion. (r = 0.17171, p = 0.0363). About 11% of the Korean adults had urinary riboflavin <27 μg/g creatinine indicating a riboflavin deficiency and 21% had low status of riboflavin (27 μg/g creatinine ≤ urinary riboflavin < 80 μg/g creatinine). Thus, one-third of Korean adults in this study had inadequate riboflavin status. In some adults in Korea, consumption of riboflavin-rich food sources should be encouraged.

Comparison of blood levels of riboflavin and folate with dietary correlates estimated from a semi-quantitative food-frequency questionnaire in older persons in Portugal

Since information regarding biochemical parameters of riboflavin and folate status is limited in some populations of older adults, a food-frequency questionnaire is often used to estimate riboflavin and folate status. However, the performance of this type of questionnaire among this age group has not been comprehensively evaluated. Thus, we sought to assess riboflavin and folate status in older adults living in Portugal and to validate findings from a semiquantitative food-frequency questionnaire (FFQ), by comparison to these blood measures. We used a cross-sectional study to investigate riboflavin in red blood cells (as Glutathione Reductase Activity Coefficient; EGRAC) and folate in the serum of 88 older persons (66.7% female), aged between 60 and 94 years, recruited from seven adult day care community centers in Porto, Portugal. Forty-six subjects had low EGRAC levels (<1.2), with a group mean concentration of 1.17 and median of 1.10 (range 1.00-2.10). For daily riboflavin dietary intakes from FFQ, the mean was 3.34 mg, the median 3.37 mg, and range 0.66-4.81 mg. The Spearman correlation between these two measures was r = 0.073, (P = 0.497) and Pearson correlation, after adjustment for energy, was r = 0.263, P = 0.013. All participants were above the 7 nmol/L serum folate cut-off for adequacy. Spearman correlation coefficient between serum and FFQ measures was r = -0.10, (P = 0.359), and the Pearson correlation, after adjustment for energy and following log(e) transformation, was r = -0.58, (P = 0.593). Thus riboflavin and folate intakes estimated by FFQ correlated poorly with EGRAC and folate serum values.

Plasma levels of copper, manganese and selenium in an adult population in southern Spain: influence of age, obesity and lifestyle factors

Copper, manganese and selenium are elements involved in protecting the body against oxidative stress. Determining their plasma level may contribute to assessing the health and nutritional status of populations. The aim of this study was to assess factors influencing copper, manganese and selenium plasma levels in an adult Mediterranean population and to identify groups at risk of deficiency. A cross-sectional survey was carried out in Andalusia, a region in southern Spain. Blood samples were obtained in a random subsample of 340 subjects. Food consumption was assessed by 48-h recall. Height, weight, skinfolds, waist and hip circumferences were measured. Copper, manganese and selenium were measured in plasma. Information about physical exercise, educational level, alcohol and smoking habits was obtained with a structured questionnaire. Plasma copper was found to be higher in women than among men. Hypocupraemia was found in 4.4% of the population, while 9.7% presented hypomanganesemia. Moreover, 86.5% presented plasma selenium values below 125microg/L (cutoff for optimal glutathione peroxidase activity). No association was found between plasma elements, anthropometric indices and lifestyle factors; there were tendencies, no more. Copper tended to decrease in obese and increase in sedentary, while selenium tended to decrease among smokers. Plasma Cu was positively correlated with the consumption of monounsaturated and polyunsaturated fats. Plasma Mn was directly correlated with the consumption of dairy products. Levels of Se were positively correlated with age, the consumption of fruit, vegetables, energy obtained from carbohydrates, and the consumption of fibre, and inversely correlated with the consumption of meat and sweets. Our results provide an estimate of the copper, manganese and selenium status in the adult population of southern Spain. The correlations found for Se suggest that there is a tendency for Se levels to be better maintained among the population that shows a stronger preference for the traditional diet.

Riboflavin supplementation and biomarkers of cardiovascular disease in the elderly

BACKGROUND

High levels of total plasma homocysteine are potentially harmful in the elderly.

OBJECTIVE

To investigated the effects of oral riboflavin supplementation on plasma total homocysteine, ferritin, uric acid and C-reactive protein concentration in elderly people with a low riboflavin status. We performed a four-week randomized, placebo-controlled, double-blind trial of riboflavin supplementation in seven Portuguese day social centers.

DESIGN

Eighty-eight individuals (66.7% female), aged between 60 and 94 years, volunteered to participate in the study following interview. Forty-two subjects, with an erythrocyte glutathione reductase activation coefficient (EGRAC) >or= 1.2, were included in the intervention trial. All subjects gave informed consent. Study subjects were administered 10 mg riboflavin (n=21) or placebo (n=21) each day for 28 days.

RESULTS

Riboflavin supplementation significantly decreased plasma tHcy (P=0.005) and EGRAC (P=0.014), but not plasma ferritin, uric acid or C-reactive protein.

CONCLUSIONS

In this elderly group, we found that 10 mg/day oral riboflavin supplementation lowered plasma homocysteine concentrations in subjects with low riboflavin status.

Influence of blood donation on levels of water-soluble vitamins

Iron depletion is a well-known side effect of blood donation. Research evidence also suggests an increasing prevalence of vitamin deficiency in apparently healthy subjects, but there is little information regarding the relationship between blood donation and vitamin status. A total of 217 volunteers (80 first-time and 137 repeat blood donors) were consecutively enrolled in the study. All subjects completed self-administered medical history and food intake forms, which included questions regarding alcohol consumption and smoking as well as on vitamin supplement, iron and contraceptive use (females). Vitamin B6, folic acid, vitamin B12 and biotin levels were measured using standard techniques. The mean vitamin levels of first-time and repeat blood donors did not significantly differ. Vitamin deficiencies occurred in both first-time and repeat blood donors but not on vitamin supplements. Vitamin status was affected by alcohol, nicotine and contraceptives. Blood donation does not decrease the level of water-soluble vitamins. Vitamin deficiencies occur in apparently healthy first-time as well as in repeat blood donors and can be prevented by vitamin supplementation.

Assessment of iron and zinc intake and related biochemical parameters in an adult Mediterranean population from southern Spain: influence of lifestyle factors

This study assessed factors influencing iron and zinc intake and associated biochemical parameters in an adult population from southern Spain to identify patterns of intake and groups at risk for deficiency. A cross-sectional survey was done in Andalusia (southern Spain) to study nutrient intakes in a random sample of 3421 subjects (1747 men, 1674 women, age between 25 and 60 years). Blood samples were obtained for biochemical assays in a random subsample of 354 subjects (170 men, 184 women). Food consumption was assessed by 48-h recall. In blood samples, we measured red blood cells, haemoglobin (Hb), haematocrit, total iron binding capacity (TIBC) and plasma concentration of Fe and Zn. Information about educational level, smoking habit, alcohol consumption and physical exercise was collected with a structured questionnaire. Intakes were below two thirds of the recommended dietary allowances (RDA) in 22.45% of the sample for Fe and in 56.45% for Zn. Iron deficiency [two or more abnormal values for plasma Fe, TIBC, transferrin saturation and mean cell volume (MCV)] was found in 12.7% of the sample, and iron-deficient anaemia (low values for Hb, MCV, mean cell Hb and mean corpuscular Hb concentration) was found in 2.1%. In smokers, plasma levels of Fe were higher, and MCV was lower than in nonsmokers. Plasma Zn concentrations were below the reference value in 17.8% of the persons. Age and body mass index correlated inversely with plasma Zn (P<.01). Gender, age, obesity, smoking, alcohol consumption and physical activity were associated with differences in nutrient intakes. Logistic regression analysis showed that female gender and older age were associated with the risk of low intakes of Fe and Zn.

Thiamine and vasculopathies

After peroxynitrite addition to aqueous solutions of thiamine at neutral and alkaline pH formation of thiamine disulfide and fluorescent products was observed. The fluorescent compounds were identified as thiochrome (TChr) and oxodihydrothiochrome (ODTChr) using spectral and fluorescent methods as well as paper chromatography and mass spectrometry. TChr and ODTChr are not the end products of thiamine oxidation and in neutral medium are unstable to peroxynitrite action and degrade rapidly to form non-fluorescent products. Thiamine, TChr, and ODTChr protects tyrosine from its modification by peroxynitrite. In the presence of TChr and ODTChr modification of tyrosinyl residues in human serum albumin and cytocrome c decreased. The prolonged thiamine incubation with glucose, amino acids and nitrite was accompanied by oxidative transformation of thiamine and formation of fluorescent products. We have shown that thiamine is also oxidized into TChr and ODTChr, i.e., it forms the same products as after thiamine oxidation by peroxynitrite. Moreover, thiamine (or its derivatives) appears as peroxynitrite scavenger leading to toxic effects lowering at diabetes mellitus.