Riboflavin Requirement Research Articles

Enhanced Uptake and Metabolism of Riboflavin in Erythrocytes Infected with Plasmodium falciparum

Riboflavin deficiency inhibits the growth of malaria parasites both in vitro and in vivo in infected animals and humans. Although the precise mechanisms underlying this inhibition are unknown, they may involve enhanced requirements for riboflavin by parasites. To investigate this possibility, the rate of uptake of [14C]riboflavin and the biosynthesis of FMN and FAD from riboflavin were studied in infected (5-8% parasitemia) and uninfected human erythrocytes. All cells were incubated for 0-3 h at 37 degrees C in phosphate buffered saline containing MgCl2, glucose, and [14C]riboflavin (2.5-7.5 microM). At hourly intervals, samples were removed, centrifuged, washed twice with cold buffer, and lysed before counting the radioactivity. The rate of in vitro biosynthesis of FMN and FAD from riboflavin in erythrocytes was measured by ion exchange chromatography and reverse isotope dilution techniques. Results showed that the rate of riboflavin uptake and the biosynthesis of FMN and FAD were enhanced in erythrocytes with parasitemia as compared with results in unparasitized erythrocytes. Riboflavin uptake in erythrocytes was proportional to the extent of parasitemia and especially to percent of schizonts present in erythrocytes. These studies indicate that the requirement for riboflavin may be greater in the parasite than in the host erythrocyte. This increased riboflavin requirement may be due to rapid multiplication, higher metabolic rate, and extreme vulnerability to oxidative stress of malaria parasites compared with that of host erythrocytes. The differential requirement of riboflavin by the host and the malaria parasite may hold important potential for developing new strategies for malaria chemotherapy.

Human requirements for riboflavin

Human requirements for riboflavin

Opening the box: Intrahousehold food allocation in rural Nepal

The study examined intrahousehold food behavior in six villages in a rural hill area of mid-Western Nepal. Qualitative and quantitative methodologies taken from both anthropology and nutritional sciences were used to collect data on food belief systems, household allocation of food resources, and the effect of these features on diet and anthropometric status in a sample of 767 individuals in 115 households. Background data were also collected on socioeconomic status and demographic variables such as education levels, occupation, and migration patterns. The core methodological approach used direct structured observations of meals to examine how food is distributed within households. The results document a variety of mechanisms by which some individuals are favored over others through household food distribution, including serving order, serving method, refusing to serve foods, channeling foods and substituting low status foods for high status foods. No differences were observed in mechanisms of food distribution or nutrient intake between male and female children, contrary to evidence in the literature suggesting that male children will be favored. On the other hand, adult women were less likely to meet their nutrient requirements for energy, beta-carotene, riboflavin, and vitamin C than men of the same age. Women's late position in household serving order, channeling of special foods to males and children, and lower total intake of food accounts for these findings.

Reassessment of riboflavin requirement for single comb white leghorn pullets from 0 to 6 weeks of age fed on maize‐soyabean meal diets and its subsequent effect on sexual maturity and egg production1

1. Two experiments were conducted using a total of 228 Hyline W-26 1-d-old pullets in each experiment. The purpose of the study was to reassess the riboflavin requirement from 0 to 6 weeks of age (WOA) and its subsequent effect on sexual maturity and egg production using a maize-soybean meal diet. 2. Approximately 10% incidence of curly toe paralysis was observed among birds fed on the diet with no added riboflavin (1.5 mg total riboflavin/kg diet). 3. Applying the non-linear regression model to the body weight gain data at 3 and 6 WOA in both the experiments, it was found that the minimum total riboflavin required to achieve maximum body weight gain for the two age periods was 2.3 and 2.0 mg/kg of the total diet. This is equivalent to 5.0 and 5.7 micrograms riboflavin/g of body weight gain from 0 to 3 and 3 to 6 WOA respectively. 4. Birds fed on the diet containing no added (1.5 mg total/kg) riboflavin laid fewer eggs and had lower body weights at 24 weeks. 5. We conclude that, from 0 to 6 WOA, at least 2.3 mg total riboflavin/kg should be present in the diet to prevent curly toe paralysis, obtain the maximum body weight gain and sustain the subsequent performance at sexual maturity.

Riboflavin Requirement of Chicks Fed Purified Amino Acid and Conventional Corn-Soybean Meal Diets

Three experiments were conducted to determine the riboflavin requirement for maximal growth of young chicks. Graded levels of crystalline riboflavin were added to either riboflavin-free, purified amino acid diets or corn-soybean meal diets. Chick growth responses were obtained upon adding riboflavin to both diets. Chicks fed the purified diet required 1.8 mg of riboflavin per kg of diet, but those fed the corn-soybean meal diet required 2.63 mg of riboflavin per kg of diet. Retarded growth and leg paralysis, rather man curled-toe paralysis, were the predominant signs of riboflavin deficiency. Calculations suggested that riboflavin bioavailability in the corn-soybean meal diet was 59.1%.

Riboflavin requirements in on-growing rainbow trout, Oncorhynchus mykiss

Rainbow trout ( O. mykiss) of 60 g mean weight were given, for 18 weeks, diets containing 0.6, 1.6, 2.7, 5.6 and 12.9 mg riboflavin/kg dry diet. A level of 2.7 mg riboflavin/kg dry diet was required to: (a) prevent the appearance of gross deficiency symptoms including ocular opacities; (b) obtain maximal riboflavin levels in liver and heart; (c) maximal activity of hepatic D-amino acid oxidase (D-AAO); (d) minimal stimulation of the activities of D-AAO, erythrocyte glutathione reductase (EGR) and hepatic glutathione reductase (HGR), after “in vitro” pre-incubation with the coenzyme flavin adenine dinucleotide (FAD). Hepatic D-AAO activity was shown to be a reliable indicator of incipient riboflavin deficiency and EGR a convenient indicator of riboflavin deficiency in the field.

Riboflavin Requirement of Turkey Poults Fed a Corn-Soybean Meal Diet from 1 to 21 Days of Age

Two battery experiments involving a total of 816 Nicholas Large White turkey poults were conducted to determine the riboflavin requirement from 1 to 21 days of age. In Experiment 1,480 poults were assigned to six dietary treatments: 0, .6, 1.1, 1.7, 3.1, and 4.4 mg supplemental riboflavin/kg basal diet. The corn-soybean meal basal diet was formulated to contain 28.5% crude protein. The vitamin premix was formulated to be devoid of riboflavin. The analyzed riboflavin content of the basal diet was 2.7 mg/kg feed. Ten replicates of eight birds per pen (four female and four male poults) were used per diet. In Experiment 2, 336 poults were assigned the same dietary treatments but with only seven replications. Using the broken line technique, it was determined that .79 ± .03 mg supplemental riboflavin/kg diet or 3.5 mg riboflavin/kg diet was needed to maximize growth. However, in order to prevent leg paralysis, slightly more riboflavin appeared to be needed.

Riboflavin Requirement of Broiler Chicks Fed a Corn-Soybean Diet

Two 21-day battery experiments were conducted with day-old broiler chicks fed a corn-soybean meal diet to re-evaluate the riboflavin requirement for optimum performance. In each experiment a total of 384 birds was assigned to six dietary treatments and given 0, 0.9, 2.0, 2.8, 3.6, or 4.4 mg of supplemental riboflavin/kg of feed. The corn-soybean meal diet was formulated to contain 22% CP and 3,200 kcal of ME/kg of feed. The analyzed riboflavin content of the unsupplemented diet was 2.6 mg/kg. A severe leg paralysis (inability to walk and to move one or both legs) was first observed between 10 to 12 days of age in birds receiving no supplemental riboflavin. Besides leg paralysis, high mortality and poor growth were the main signs of riboflavin deficiency observed. A minimum requirement for growth of 3.6 mg of riboflavin/kg of feed was determined using the broken-line technique. However, in order to prevent signs of leg paralysis, the minimum requirement of 4.6 mg riboflavin/kg of feed was suggested. Based on the maximum feed intake (834 g) observed for birds to reach maximum body weight (593 g) at 21 days of age, a minimum intake of approximately 6.5 μg riboflavin/g body weight was needed for maximum performance.

Riboflavin requirement of lactating swine.

Twenty-five crossbred gilts and 25 crossbred sows were used in an experiment to estimate the riboflavin requirement of lactating swine. During gestation the females were fed a 12% crude protein, corn-soybean meal diet that was marginal in riboflavin content, i.e., 2.3 mg/kg. After farrowing, litter size was equalized across lactation diets within each parity category. The basal, 14% crude-protein corn-soybean meal lactation diet was supplemented to provide five levels of dietary riboflavin: 1.25, 2.25, 3.25, 4.25 and 5.25 mg/kg. Five gilts and five sows were fed each dietary treatment. Each dam was provided her assigned diet ad libitum during the 24-d lactation; piglets were not provided supplemental feed. The erythrocyte glutathione reductase activity coefficient (EGRAC), an indicator of riboflavin status, was measured on blood samples obtained from the dams and their piglets on d 1 and d 24 postpartum. On d 1, the mean EGRAC of gilts was slightly higher than that of sows, while piglet EGRAC was similar regardless of maternal age. On d 24 gilts and their piglets had higher average EGRAC (P less than .01) than did sows and their piglets. Thus, there was a treatment x dam age interaction (P less than .05). Lactation performance criteria gave further evidence of similar treatment x age group interactions. Gilts fed the diet containing 1.25 ppm riboflavin had higher piglet mortality, consumed less feed and lost more weight (P less than .05) for each criterion than did sows fed the same diet. Despite these observations, the broken-line estimates of the riboflavin requirement, based on EGRAC, for gilts and sows were 16.3 and 16.2 mg/d, respectively. The EGRAC values for piglets closely paralleled those of their dams regardless of treatment, suggesting that there is no mechanism to protect the nursing piglets from a maternal dietary deficiency of riboflavin.

Physical training and fasting erythrocyte activities of free radical scavenging enzyme systems in sedentary men.

Effects of 10 weeks of physical training on free radical scavenging enzyme systems in erythrocytes were investigated in 7 sedentary healthy male students. The training consisted of running over 5 km, 6 times/week. Their maximum oxygen uptake and 12 min walk-run performance increased significantly after training. Of the antioxidant enzyme systems examined in the erythrocytes, both catalase activity and concentration and total glutathione reductase (GR) activity also showed significant increases following the training. The erythrocyte GR activity coefficient also increased significantly. These results suggest that chronic aerobic exercise increases riboflavin requirements and has some positive effects on antioxidative processes.

Vitamins and exercise???an update

Although no conclusive evidence exists to suggest that vitamin supplementation improves athletic performance in nutritionally adequate individuals, exercise may increase requirements for certain vitamins in individuals with marginal vitamin stores. This review summarizes results from recent research studies of vitamins and exercise. Exercise increased the requirement for riboflavin and vitamin C; however, vitamin supplementation improved the ability to train only in vitamin C-depleted individuals. No measurable effect of supplemental thiamin, riboflavin, or vitamin B6 on performance was observed in any of the reported studies. Exercise acutely affected vitamin B6 metabolism. Confusion regarding vitamin supplementation and exercise performance may stem from a lack of adequate research data. Recommendations for future research are presented.

Human requirements for riboflavin

Human requirements for riboflavin

Effect of Exercise on Riboflavin Status of Rats

The effect of exercise on the riboflavin status of male rats was studied after 6 or 8 wk of treadmill running. Sedentary and exercised rats were pair fed diets marginal in riboflavin (2.0 or 2.5 mg/kg), and their tissue riboflavin concentrations and erythrocyte glutathione reductase activity coefficients (EGRAC) were compared. The rats exercised for 8 wk had similar body weights but significantly greater weights for heart, gastrocnemius and soleus muscles, less epididymal fat and more total muscle nitrogen and riboflavin than their sedentary controls. Similar changes were evident after 6 wk of exercise, but some were not statistically significant. The EGRAC values of both exercised and sedentary rats responded to changes in dietary riboflavin but were not different from each other. The specific activity of mitochondrial acyl-CoA dehydrogenase (per milligram protein) of the soleus muscle was unaffected by exercise; however, when expressed per gram of tissue or per muscle, the activities in exercised rats were 25% (P<0.05) and 60% (P<0.01) higher, respectively, than in sedentary rats. On the basis of the riboflavin-dependent parameters measured in this study, exercise did not increase the dietary riboflavin requirement of growing rats but did increase total riboflavin retention in gastrocnemius and soleus muscles.

Occurrence and significance of riboflavin deficiency in preterm infants.

Few studies have explored the importance of riboflavin deficiency in premature infants. Infants receiving human milk during the first 2 weeks become biochemically riboflavin-deficient, partly through photodegradation of riboflavin during the banking and delivery of human milk. Animal studies have shown that the metabolic lesions of riboflavin deficiency in sucking neonates differ in important ways from those seen later after weaning. Techniques are described for non-invasive study of functional riboflavin requirements by premature infants. It appears prudent to supplement human milk-fed babies with at least 300 micrograms riboflavin/day; but the potential danger of over supplementation in infants exposed to phototherapy is discussed.

Interpretations of requirements for thiamin, riboflavin, niacin-tryptophan, and vitamin E plus comments on balance studies and vitamin B-6

Data from the long-term projects sponsored by the Food and Nutrition Board to determine the requirements for thiamin, riboflavin, niacin-tryptophan, and vitamin E are utilized to effect an opinion regarding the recommended dietary allowances for these vitamins. Based upon data obtained during these and subsequent research projects, comments on balance studies, changes in tissue lipids, and the requirements for vitamin B-6 are included. The possibility that antioxidants may have an effect on delaying oncogenesis is discussed.

Effects of exercise on riboflavin requirements: biological validation in weight reducing women

The present study was designed to evaluate our previous estimates for riboflavin requirement, 0.96 mg/1000 kcal during nonexercise and 1.16 mg/1000 kcal during exercise in overweight women. Two groups of 6 weight reducing women consumed either 1.16 mg riboflavin/1000 kcal (HR) or 0.96 mg/1000 kcal (MR). The study was two, 3 period by 2 treatment (exercise or nonexercise) crossover designs, one design at each level of riboflavin. Erythrocyte glutathione reductase activity coefficients (AC) significantly increased in both groups from 1.16 +/- .02 to 1.20 +/- .03 in group HR and from 1.31 +/- .04 to 1.36 +/- .02 in the MR group during nonexercise and exercise, respectively. ACs increased in the HR group due to an increase in total enzyme activity while ACs increased in the MR group due to a decrease in basal enzyme activity reflecting decreased flavin availability. There were no differences in aerobic capacity, weight loss, nor change in lean body mass between the two groups. Thus, 0.96 mg/1000 kcal was not adequate during either nonexercise or exercise periods while the 1.16 mg/1000 kcal was adequate.

Riboflavin Requirement for Growth, Tissue Saturation and Maximal Flavin-Dependent Enzyme Activity in Young Rainbow Trout (Salmo gairdneri) at Two Temperatures

Two temperatures (10° and 15°C) and two fish stocks differing in growth potential were used to determine the dietary riboflavin requirement of young rainbow trout (Salmo gairdneri) on the basis of growth parameters, tissue saturation and a flavin-dependent biochemical function. Two experiments were conducted with purified diets based on vitamin-free casein. In experiment 1, fry (initially 2.0 g/fish) were fed, for 16 wk at 15°C, diets containing 0.6, 2.6, 3.6, 4.6, 5.6 or 6.6 mg riboflavin per kilogram diet. In experiment 2, fry (initially 1.7–1.8 g/fish) were held at either 10° or 15°C and fed, for 10 wk, diets containing 0.7, 2.7, 3.7, 4.7, 6.7 or 8.7 mg riboflavin per kilogram. The riboflavin requirements for maximal growth rate, liver flavin saturation, spleen and head kidney flavin saturation and maximal hepatic D-amino-acid oxidase activity were 3.6, 4.6, 6.6 and 5.6 mg/kg diet, respectively, in a diet containing 40% crude protein and 15% ether extract. The requirements were not affected by temperature or by genetically determined differences in maximal growth rate. When expressed on a dietary energy basis, the riboflavin requirements of the trout for maximal growth rate and liver flavin saturation appear similar to those of several homeothermic species.

Riboflavin requirement of gestating swine.

Forty crossbred gilts (9 to 10 mo of age) were used to determine the riboflavin requirement for gestating swine. Upon mating, gilts were assigned to one of five levels of dietary riboflavin (.77, 1.77, 2.77, 3.77 or 4.77 ppm) and individually fed 2.0 kg daily of the assigned diet throughout gestation. Gilts were bled on d 7, 24, 30, 35, 40, 56, 70, 84, 90 and 97 postcoitum. On d 1 postpartum, all sows and their live piglets were bled. Hemolysates of isolated, washed erythrocytes were prepared from blood samples and assayed to establish the erythrocyte glutathione reductase activity coefficient (EGRAC) as an indicator of the riboflavin status of each animal. The higher the EGRAC, the greater the severity of the riboflavin deficiency. During gestation, the EGRAC of gravid gilts increased with time in a manner dependent upon the level of dietary riboflavin. Postpartal EGRAC were elevated in dams fed the three lowest levels of dietary riboflavin during gestation. Of the six gravid gilts fed .77 ppm riboflavin, four gilts gave birth, approximately 7 d prematurely, to stillborn litters while two gilts failed to farrow by 121 d postcoitum. Litter weights at birth and gestation weight gains of these gilts were less than those of gilts fed the higher levels of riboflavin. Postnatal mortality of piglets was greater for those litters from sows fed 1.77 ppm riboflavin than for those from sows fed higher levels of riboflavin. The riboflavin status of newborn piglets was similar to that of their dams as determined by EGRAC.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of aerobic exercise and weight loss on riboflavin requirements of moderately obese, marginally deficient young women

In a previous study, exercise was shown to increase riboflavin requirements of active, normal weight young women. The present study examined the effect of exercise and weight loss on riboflavin status of moderately overweight women. The experiment was designed as a two-period cross-over with an initial base-line period and two 5-wk metabolic periods. The basic diet contained 1200 kcal with a riboflavin concentration of 0.8 mg/1000 kcal. Exercise consisted of a program of dance exercise. Riboflavin depletion, as measured by increased erythrocyte glutathione reductase activity coefficients and decreased urinary excretion of riboflavin, occurred during both nonexercise and exercise periods. Erythrocyte glutathione reductase activity coefficients increased from a base-line mean of 1.28 ± 0.11 to 1.40 ± 0.12 during nonexercise and to 1.49 ± 0.16 during exercise. Urinary excretion of riboflavin fell from 48 ± 12% of intake during base-line to 30 ± 13% during nonexercise and to 19 ± 6% during exercise. Riboflavin depletion was not related to the rate or composition of weight loss or to change in aerobic capacity.

Riboflavin deficiency and the preterm infant

Riboflavin (B2) plays a central role in intermediary metabolism and energy release; little is known about riboflavin requirements or pathophysiological consequences of deficiency states in preterm (PT) infants. 68 infants were allocated randomly to diets including human milk or a preterm formula containing 1.8 mg riboflavin/1. 18 of 23 human milk fed infants, who had not received supplementary riboflavin before day 7, developed biochemical riboflavin deficiency (erythrocyte glutathione reductase activation coefficient >1.3) compared with a low incidence in the formula fed group (p<0.01). Dietary effects of riboflavin status out-weighed those of phototherapy. Further studies demonstrated significant photodegredation of riboflavin in breastmilk during home collection, handling and enteral infusion: controlled exposure to daylight of human milk in plastic storage bottles or infusion apparatus, resulted in 40-50% destruction over 6 h (also 70% vitamin A lost): these losses may compound deficiency. Phototherapy lighting was similarly destructive. Our preliminary work on neonatal and older rats demonstrate that experimental riboflavin deficiency decreases oxygen consumption (p<0.05) and decreases (p<0.05) iron utilization and fatty acid oxidation (the latter suggested also by early studies on PT neonates). We speculate that riboflavin deficiency in PT infants might impair energy metabolism and substrate utilization though early supplementation requires caution since light degraded riboflavin may release damaging free radicals.