Effects of dietary vitamin B6 supplementation on fillet fatty acid composition and fatty acid metabolism of rainbow trout fed vegetable oil based diets

Fish oil replacement in aquaculture feeds results in major modifications to the fatty acid makeup of cultured fish. Therefore, in vivo fatty acid biosynthesis has been a topic of considerable research interest. Evidence suggests that pyridoxine (vitamin B(6)) plays a role in fatty acid metabolism, and in particular, the biosynthesis of LC-PUFA has been demonstrated in mammals. However, there is little information on the effects of dietary pyridoxine availability in fish fed diets lacking LC-PUFA. This study demonstrates a relationship between dietary pyridoxine supplementation and fatty acid metabolism in rainbow trout. In particular, the dietary pyridoxine level was shown to modulate and positively stimulate the activity of the fatty acid elongase and Δ-6 and Δ-5 desaturase enzymes, deduced by the whole-body fatty acid balance method. This activity was insufficient to compensate for a diet lacking in LC-PUFA but does highlight potential strategies to maximize this activity in cultured fish, especially when fish oil is replaced with vegetable oils.     

Complementary foods consumed by 6-12-month-old rural infants in South Africa are inadequate in micronutrients

OBJECTIVE: To determine the nutrient composition of complementary foods consumed by 6-12-month-old South African infants. DESIGN: Nutrient intake was determined for infants who were recruited to participate in a randomised controlled trial using a single 24-hour dietary recall. SETTING/SUBJECTS: Infants aged 6-12 months (n=475) residing in The Valley of a Thousand Hills, a rural area in KwaZulu-Natal, South Africa. RESULTS: Energy and protein intakes from complementary foods were adequate. Infants who consumed infant products (commercially available fortified infant cereals/ready-to-eat canned baby foods/formula milk powder) had significantly higher intakes of calcium, iron, zinc, vitamin A, thiamine, riboflavin, niacin, vitamin B6, vitamin B12 and vitamin C than infants who did not consume any infant products. For infants who consumed infant cereals (n=142), these cereals provided 51% of total iron intake. Infant cereals provided more than 25% of total intake for magnesium, thiamine, niacin and vitamin B12. For infants consuming ready-to-eat canned baby foods (n=77), these products contributed less than 15% of total intake for all the micronutrients. The nutrient density of the complementary diet was less than half the desired density for calcium, iron and zinc. Animal products were consumed by 17% of infants, 26% consumed dairy products and 18% consumed vitamin-A-rich fruit and vegetables during the 24-hour recall period. CONCLUSION: The nutrient composition of complementary foods among rural South African infants was inadequate, especially for iron, zinc and calcium. Strategies should be developed to improve the nutritional quality of their diets.     

Homocysteine and cobalamin status in German vegans

OBJECTIVE: The study aimed to evaluate the homocysteine and cobalamin status of German vegans and determine whether the intake of very small amounts of foods of animal origin can improve this status. DESIGN AND SETTING: Cross-sectional study, Germany. SUBJECTS: The dietary and nutritional intakes of 131 vegans (73 women, 58 men; age range: 20.2-82.1 years) were evaluated using a general questionnaire and two food-frequency questionnaires. RESULTS: The prevalence of inadequate cobalamin status in volunteers of the German Vegan Study was 28.2%, and that of hyperhomocysteinaemia, 38.1%. Moderate vegans were affected to a lesser extent than were strict vegans. Duration of veganism and cobalamin concentration were inversely correlated (Spearman's r=-0.175, P=0.047). Folate concentration and erythrocyte aspartic acid aminotransferase activity were not correlated with plasma homocysteine concentration, but duration of veganism correlated positively with homocysteine concentration (Spearman's r=0.319, P<0.001). Cobalamin and homocysteine concentrations were inversely correlated (when controlling for duration of veganism; r=-0.602, P<0.001). CONCLUSION: Cobalamin status needs to be improved in order to minimise the risk of hyperhomocysteinaemia.     

Genotype and environment effects on the contents of vitamins B1, B2, B3, and B6 in wheat grain

The total contents of thiamine (vitamin B1), riboflavin (B2), and pyridoxine (B6) and the bioavailable forms of niacin (B3) were determined on wholemeal flours of 24 winter wheat varieties grown on four sites (United Kingdom, Poland, France, and Hungary) in 2007 and of two spring varieties grown on the same sites with the exception of Poland. The contents of vitamins B1 (5.53-13.55 μg/g dw), B2 (0.77-1.40 μg/g dw), and B6 (1.27-2.97 μg/g dw) were within the ranges reported previously, while the content of bioavailable vitamin B3 (0.16-1.74 μg/g dw) was about 10-15% of the total contents of vitamin B3 reported in previous studies. Strong correlations were observed between the contents of vitamins B1, B3, and B6, and partitioning of the variance in the contents of these three B vitamins showed that between 48 and 70% was accounted for by the environment. By contrast, the content of vitamin B2 was not correlated with the contents of other B vitamins, and 73% of the variance was ascribed to the error term, which suggests that this trait may be influenced by genotype × environment interactions. Whereas the contents of vitamins B1, B3, and B6 were correlated positively with the mean temperature from heading to harvest (r > 0.8), the content of vitamin B2 was positively correlated with precipitation during the 3 months prior to heading. These results are discussed in relation to the development of new wheat varieties with enhanced health benefits.     

Impact of disaggregation of composite foods on estimates of intakes of meat and meat products in Irish adults

OBJECTIVE: To evaluate the impact of the disaggregation of composite foods on intake estimates of meat and individual meat categories and on the contribution of meat to nutrient intakes in Irish adults. DESIGN: Data were analysed from the North/South Ireland Food Consumption Survey, which used a 7-day food diary to estimate food intake. Of 742 food codes that contained meat, 320 were codes for meat consumed as an individual portion and 422 were composite foods and were disaggregated to estimate the meat content. SUBJECTS: A nationally representative sample of 475 men and 483 women (not pregnant or lactating) from the Republic of Ireland aged 18-64 years. RESULTS: The mean intake of meat was 134 g day(-1) in consumers (98.5%) and men (168 g day(-1)) consumed significantly more (P<0.001) than women (102 g day(-1)). Mean intakes of meat were higher in subjects with manual skilled occupations (P<0.01) and lower in those with third-level educational qualifications (P<0.05). Without disaggregating meat from composite foods, meat intake was overestimated by 43% (57 g day(-1)) and varied widely by meat category. Meat disaggregated from composite foods contributed 25% of meat intake. The contribution meat made to nutrient intakes ranged from 29% for protein, vitamin B12, zinc and niacin to 20% for vitamin D, 16% for vitamin B6, 15% for thiamine and 14% for iron. CONCLUSIONS: Failure to disaggregate meat from composite foods substantially overestimates meat intake, with a large variation between meat categories. This has important implications for estimates of meat intakes in nutritional epidemiological studies and for food safety purposes.     

Chemistry behind Vegetarianism

This review summarizes the effect of a habitual vegetarian diet on clinical complications in relation to chemistry and biochemistry. Omnivores have a significantly higher cluster of cardiovascular risk factors compared with vegetarians, including increased body mass index, waist to hip ratio, blood pressure, plasma total cholesterol (TC), triacylglycerol and LDL-C levels, serum lipoprotein(a) concentration, plasma factor VII activity, ratios of TC/HDL-C, LDL-C/HDL-C and TAG/HDL-C, and serum ferritin levels. Compared with omnivores, vegetarians, especially vegans, have lower serum vitamin B?? concentration and n-3 polyunsaturated fatty acid (PUFA) levels in the tissue membrane phospholipids, which are associated with increased collagen and ADP stimulated ex vivo whole blood platelet aggregation, plasma 11-dehydrothromboxane B?, and homocysteine levels and decreased plasma HDL-C. This may be associated with an increased thrombotic and atherosclerotic risk. It is suggested that vegetarians, especially vegans, should increase their dietary n-3 PUFA and vitamin B?? intakes.     

National fortification of staple foods can make a significant contribution to micronutrient intake of South African adults

BACKGROUND: A national survey found that micronutrient deficiencies are prevalent in South African children, particularly calcium, iron, zinc, riboflavin, niacin, vitamin B6, folate, vitamin A, E and C. Mandatory fortification of maize meal and wheat flour were introduced in 2003 to combat some of the deficiencies found in children. To date however, there has not been a national survey on dietary intake in adults. OBJECTIVES: The main objectives of this study were to evaluate the micronutrient intake of the diet consumed by the average adult South African by means of secondary data analyses and secondly to evaluate the effects of fortification on selected nutrient intakes. STUDY DESIGN: Secondary data analysis was carried out with numerous dietary surveys on adults to create a database that included sampling (and weighting) according to ethnic/urban-rural residence in line with the population census, of which 79% were black Africans and the majority resided in rural areas. The effect of fortification was evaluated by substituting fortified foods in the diet for the unfortified products. SUBJECTS: The combined database used in this study comprised 3229 adults. RESULTS: Mean calcium, iron, folate and vitamin B6 intakes were very low particularly in women. Mean intakes of most micronutrients were lower in rural areas. Fortification of maize meal and wheat flour (bread) raised mean levels of thiamine, riboflavin, niacin, vitamin B6 and folate above the recommended nutrient intakes (RNIs). In women, despite fortification, mean iron intakes remained below the RNIs, as did calcium since it was not in the fortification mix. CONCLUSION: The average dietary intake of adults was of poor nutrient density, particularly in rural areas. Fortification of maize meal and wheat flour (bread) considerably improved mean vitamin B6, thiamine, riboflavin, niacin, folate and iron intakes as well as the overall mean adequacy ratio of the diet.     

Dried green and purple lavers (Nori) contain substantial amounts of biologically active vitamin B(12) but less of dietary iodine relative to other edible seaweeds

Vitamin B(12) concentrations of dried green (Enteromorpha sp.) and purple (Porphyra sp.) lavers (nori) were determined by both Lactobacillus leichmannii ATCC 7830 microbiological and intrinsic factor chemiluminescence methods. The values determined by using the microbiological method (63.58 +/- 2.90 and 32.26 +/- 1.61 microg/100 g of dry weight) were identical to those found by using the chemiluminescence method (69.20 +/- 2.21 and 25.07 +/- 0.54 microg/100 g of dry weight) in both dried green and purple lavers, respectively. A silica gel 60 thin-layer chromatography of both laver extracts shows that non-coenzyme forms (hydroxo and cyano forms) of vitamin B(12) predominate in both dried lavers. The dried lavers contained lesser amounts of dietary iodine ( approximately 4-6 mg/100 g of dry weight) relative to other seaweeds, suggesting that excessive intake of the dried lavers is unlikely to result in harmful intake of dietary iodine. These results indicate that the dried lavers (nori) are the most excellent source of vitamin B(12) among edible seaweeds, especially for strict vegetarians.     

Issues in assessing the validity of nutrient data obtained from a food-frequency questionnaire: folate and vitamin B12 examples

OBJECTIVE: To compare methods used to assess the validity of nutrient intake data obtained from a food-frequency questionnaire (FFQ), using folate and vitamin B12 as nutrient examples. DESIGN: Cross-sectional sample from a population cohort. SETTING: Two postcode areas west of Sydney, Australia. SUBJECTS: In total, 2895 people aged 49 years and older provided dietary data using a semi-quantitative FFQ (79% of 3654 subjects examined). The validity of the FFQ was assessed against three 4-day weighed food records (WFRs) completed by 78 people (mean age 70 years). RESULTS: Folate and vitamin B12 validity data were assessed using different methods. The Spearman ranked correlations (energy-adjusted) were 0.66 for folate and 0.38 for vitamin B12. Using the Bland-Altman method, following loge transformation, no linear trend existed between the differences and means for folate and vitamin B12. Large differences existed between the FFQ and WFR in individual cases, particularly for vitamin B12. Finally, data were divided into quintile categories for the test and reference method: 79% classified folate within one quintile, 65% classified vitamin B12 within one quintile; there was no gross misclassification for folate and only 3% misclassification for vitamin B12. CONCLUSIONS: Different methods of analysis provided different information about the validity of the FFQ. Correlation coefficients should not be used alone to assess the validity of nutrient data, but should be used in conjunction with Bland-Altman analyses. Depending on the use of the data, additional assessment of classification categories is recommended. This worked example demonstrates that absolute intakes of folate and vitamin B12 should be used with caution.     

Dietary intake and body mass index in HIV-positive and HIV-negative drug abusers of Hispanic ethnicity

OBJECTIVE: Malnutrition in drug abusers has been attributed to poor diet. However, previous studies are conflicting. Many studies have not considered possible concurrent HIV disease. The purpose of this study was to determine the relationship between drug abuse and dietary intake in Hispanic Americans with and without HIV infection. DESIGN: Dietary intake was measured using 3-day food records and 24-hour dietary recalls in three groups: HIV-positive drug abusers, HIV-negative drug abusers and HIV-positive persons who do not use drugs ('non-drug abusers'). SETTING: The baseline data from a prospective cohort study of the role of drug abuse in HIV/AIDS weight loss and malnutrition conducted in Boston, Massachusetts, USA. SUBJECTS: The first 284 participants to enroll in the study. RESULTS: HIV-positive drug abusers had a body mass index (BMI) that was significantly lower than that of HIV-positive non-drug abusers. Reported energy, fat and fibre intakes did not differ between groups. All groups had median reported intakes of vitamin A, vitamin B6, vitamin B12, selenium and zinc that were in excess of the dietary reference values (DRI). Intakes of alpha-tocopherol were below the DRI, but did not differ from intakes of the general US population. However, increasing levels of drug abuse were associated with lower reported intakes of vitamin B6, vitamin B12, selenium and zinc. CONCLUSIONS: Overall, this study does not support the notion that dietary intake can explain the lower BMI of HIV-positive drug abusers. Further studies examining non-dietary determinants of nutritional status in drug abusers are warranted.     

The influence of fruit and vegetable intake on the nutritional status and plasma homocysteine levels of institutionalised elderly people

OBJECTIVE: To determine the difference in the nutritional status of elderly people depending on their consumption of fruits and vegetables, and to study the possible association between the consumption of these foods and different cardiovascular risk factors, especially total plasma homocysteine (t-Hcys) levels. DESIGN, SETTING AND SUBJECTS: A cross-sectional study in 152 institutionalised older people from Madrid aged > or = 65 years. Food and nutrient intakes were recorded over 7 days using the 'precise individual weighing' method. The weight, height, and waist and hip circumferences of all subjects were recorded, as were their alpha-erythrocyte glutathione reductase, serum B6, B12 and folate levels, erythrocyte folate levels, t-Hcys levels, serum lipids and blood pressure. The experimental population was then divided into tertiles depending on the serving intake of fruit and vegetables (T1, < 2.29 servings day(-1); T2, 2.29-2.79 servings day(-1); and T3, >2.79 servings day(-1)). RESULTS: Compared with T1 subjects, T3 subjects showed consumptions of cereals, pulses, meat, fish and eggs closer to those recommended (P < 0.05). In addition, the contribution of their diet towards covering the recommended daily intake of vitamin B1, niacin, vitamin B6, folic acid, vitamin C, B12, vitamin A, and P, Mg, Zn and Fe was higher. The intake of fibre increased with consumption of fruit and vegetables (r = 0.6839, P < 0.001). T3 subjects also had better serum and erythrocyte folate levels than T1 and T2 subjects (P < 0.05). A positive correlation was found between the consumption of fruit and vegetables and serum folate (r = 0.2665, P < 0.01) and with erythrocyte folate levels (r = 0.2034, P < 0.05), and a negative correlation with t-Hcys (r = -0.2493, P < 0.01). CONCLUSIONS: Greater consumption of fruit and vegetables is associated with better food habits, increased vitamin and mineral intakes and lower t-Hcys levels. Considering that the fruit and vegetable intake in Spanish elderly people is very low, it is recommended that the consumption of fruits and vegetables by elderly people be increased.     

The impact of high non-starch polysaccharide intake on serum micronutrient concentrations in a cohort of women

OBJECTIVE: Many public health campaigns encourage increased fibre consumption, but short-term studies suggest that various components of dietary fibre inhibit the absorption of certain micronutrients including carotenoids. These do not take into account long-term adaptation to nutrient intake levels. We aimed to investigate the effect of non-starch polysaccharide (NSP) fibre on plasma micronutrient concentrations in a large free-living population consuming their usual diet. DESIGN: Prospective cohort study. Semi-weighed 4-day food diaries were analysed for micronutrient and NSP fibre intakes. Blood samples were taken and analysed for carotenoids, vitamin A, vitamin E, thiamine, riboflavin, vitamin B6, vitamin B12, folic acid, vitamin C and trace metals. SETTING: Participants in a large national cohort study who lived within 30 miles of Leeds. SUBJECTS: Two hundred and eighty-three middle-aged women. RESULTS: The association between NSP intake and plasma nutrient concentrations was assessed taking into account nutrient intakes and other dietary and lifestyle factors. Higher levels of NSP were not associated with lower plasma concentrations of the micronutrients measured, even allowing for the higher nutrient levels generally found in high-fibre foods. CONCLUSIONS: Amongst middle-aged women we have shown that current guidelines for increasing the population's NSP consumption can be safely applied. Such guidelines are unlikely to reduce serum micronutrient concentrations, although other, more vulnerable population groups may benefit from further investigation.     

Characterization of a vitamin B12 compound from unicellular coccolithophorid alga (Pleurochrysis carterae).

A unicellular coccolithophorid alga, Pleurochrysis carterae, contained 125.4 +/- 1.2 microg of vitamin B12 per 100 g dry cell weight of the lyophilized algal cells. A vitamin B12 compound was purified from the lyophilized algal cells and partially characterized. The silica gel 60 TLC and reversed-phase HPLC patterns of the purified pink-colored compound were identical to those of authentic vitamin B12, but not those of vitamin B12 analogues inactive for humans. When 22-week-old B12-deficient rats which excreted substantial amounts of methylmalonic acid (75.5 +/- 12.3 mg/day) in urine were fed the P. carterae (10 g per kg diet)-supplemented diet for 12 d, urinary methylmalonic acid excretion (as an index of vitamin B12 deficiency) of the rats became undetectable and hepatic vitamin B12 level of the rats was significantly increased.     

Impact of deliquescence on the chemical stability of vitamins B1, B6, and C in powder blends

Single vitamin ingredients and blends in premixes are widely used in the food and supplement industries and are predominantly in powder form. To meet label claims and/or determine appropriate overages, it is important to characterize the stability of these ingredients. Although moisture is a known promoter of instability in powder blends, the combined effects of storage relative humidity (RH), formulation, and deliquescence on the stability of these systems are not well-characterized. The objective of this study was to determine the effect of deliquescence on the stability of vitamins B 1, B 6, and C and their mixtures. Deliquescence points (RH 0s) for all formulations were determined by moisture sorption analysis. Single, binary, ternary, and quaternary mixtures of thiamin HCl, pyridoxine HCl, sodium ascorbate, and fructose were stored in RH-controlled environmental chambers between 43 and 98% RH at 22 degrees C for up to 12 weeks. Vitamin stability was determined by high-performance liquid chromatography (HPLC). Formulation and storage RH significantly affected vitamin stability. Thiamin and ascorbate degradation were significantly promoted above the RH 0, while pyridoxine was least affected by storage RH. The deliquescence lowering phenomenon enhanced moisture sorption of blends at RHs below the RH 0s. Ascorbate enhanced thiamin degradation. Therefore, formulation, storage conditions, and the relation of these to deliquescence points may affect the shelf life, quality, and functionality of vitamin blends and should be considered in product development, processing, storage, and use.     

Radiometric microbiological assay of vitamin B6: assay simplification and sensitivity study

Modification of a previously developed radiometric microbiological assay for vitamin B6 reduces assay complexity and time. Reduction of enzymatic treatment from 24 to 3 h essentially eliminates one day's time for the analysis of plasma samples. Use of lyophilized Kloeckera brevis cultures eliminates routine subculturing of the test organism, with no significant effect on test results. Modifications in test vial size and total volume in test vials have increased assay sensitivity to a level of 0.25 ng pyridoxine (PN), pyridoxal (PL), or pyridoxamine (PM) per vial level and decreased the amount of medium and labeled substrate (i.e., L-[1-14C]-valine), thus reducing assay cost.     

Intake and sources of phylloquinone (vitamin K(1)) in 4-year-old British children: comparison between 1950 and the 1990s

OBJECTIVES: To compare dietary intake and sources of phylloquinone (vitamin K1) in 4-year-old British children between 1950 and the 1990s, and report their variation by sociodemographic factors.Design: Nationally representative samples of 4-year-olds from the longitudinal Medical Research Council National Survey of Health and Development (NSHD) (1950) and the cross-sectional National Diet and Nutrition Surveys (NDNS, 1992/93 and 1997). SETTING: Great Britain. SUBJECTS: Subjects were 4599 children born on 3-9 March 1946 (NSHD) and 307 children in the 1990s (NDNS). RESULTS: Geometric mean dietary phylloquinone intake was significantly higher in 1950 (39 mug day(-1), 95% confidence interval (CI) 37, 40) compared with the 1990s (24 mug day(-1), 95% CI 22, 25) (P<0.001). This difference remained when intake was expressed per MJ energy intake and per kilogram body weight, and after accounting for sex, region and occupational social class of the family. In 1950, phylloquinone intake in Scotland was significantly lower than in the rest of Britain. By the 1990s these regional differences had disappeared. Food sources of phylloquinone intake changed significantly between 1950 and the 1990s, with fats and oils contributing more and vegetables less, although vegetables contributed most (60% and 48%, respectively) to phylloquinone intake in both surveys. CONCLUSIONS: Phylloquinone intakes of children have decreased significantly since 1950. With the suggested need for adequate phylloquinone intake for optimal development and maintenance of bone and the cardiovascular system, the substantially lower phylloquinone intakes reported in children of the 1990s, compared with 1950, may have implications for the health of these two systems in later adulthood.     

Determination of vitamin B(6) in cooked sausages

A reverse-phase high-performance liquid chromatography (HPLC) method has been described for the determination of various active forms of vitamin B(6) in meat products. Different extracting agents were tested to solubilize fully the analyte for quantification. The best data were obtained by extracting the samples with 5% (w/v) metaphosphoric acid. Separation by HPLC was performed with fluorescence detection (excitation, 290 nm; emission, 395 nm), on a 10 cm x 0.46 cm i.d. Hypersil BDS C(18) 5 microm column using a mixture of 50 mM phosphate buffer (pH 3.2) and acetonitrile (99:1, v/v) as mobile phase. Precision of the method was 0.5% (within a day) and 4.3% (between days). The detection limits were 0.020 mg/100 g for pyridoxal and pyridoxamine, 0.017 mg/100 g for pyridoxamine phosphate, 0.500 mg/100 g for pyridoxal phosphate, and 0.033 mg/100 g for pyridoxol, with a signal-to-noise ratio of 3. The recovery ranged from 92.0 to 100.0%.     

Inhibition of diphenolase activity of tyrosinase by vitamin b(6) compounds

The vitamin B(6) compounds pyridoxine (PN), pyridoxamine (PM), pyridoxal (PL), and pyridoxamine 5'-phosphate (PMP) inhibited the diphenolase activity of mushroom tyrosinase. PM showed the highest inhibition; the control activity was inhibited by 38% at 1.5 mM. Each PL, PN, and PMP showed about 30% inhibition at the same concentration. Lineweaver-Burk plots showed that PM and PN were mixed-type inhibitors with K(I) values of 4.3 and 5.2 mM, respectively. Because PM and PN cannot form a Schiff base with a primary amino group of the enzyme, their inhibition is not attributable to the formation of the Schiff base. Alternatively, their quenching function of reactive oxygen species (ROS) was postulated to be responsible for the inhibition. Thus, the inhibitory effect of ROS was examined. The representative singlet oxygen quenchers l-histidine, sodium azide, Trolox, and anthracene-9,10-dipropionic acid (AAP) inhibited the activity. The specific scavenger of superoxide, proxyl fluorescamine, also inhibited the activity. The scavengers of hydroxyl radical, d-mannitol and dimethyl sulfoxide, showed no inhibition. The fluorescence of AAP was decayed during the diphenolase reaction, and PM inhibited the decay. AAP was also a mixed-type inhibitor. The results showed that the vitamin B(6) compounds inhibited the diphenolase activity by quenching ROS (probably singlet oxygen) generated during some reaction step of the diphenolase reaction.     

Tracking of energy and nutrient intakes from adolescence to young adulthood: the experiences of the Young Hearts Project, Northern Ireland

OBJECTIVE: To assess tracking of energy and nutrient intakes between adolescence and young adulthood. DESIGN: Longitudinal study of a random sample of adolescents (aged 15 years at baseline). The extent of tracking of dietary intakes (assessed by diet history) was investigated using weighted kappa statistics (kappa). SETTING: Northern Ireland population survey. SUBJECTS: Adolescents who participated in the Young Hearts Project, Northern Ireland at age 15 years, and subsequently at young adulthood aged between 20 and 25 years (n=245 males, n=231 females). RESULTS: Despite overall increases in height and weight (both P<0.001), increases in body mass index in males (P<0.001) and body fatness in females (P<0.001), median reported intakes of energy (kJ kg(-1) day(-1)), carbohydrate (g day(-1)) and fat (g day(-1)) decreased (all P<0.001) over time. Expressed as nutrient densities (per MJ), diets at young adulthood were overall richer in thiamin, vitamin B6, total folate (all P<0.001), vitamin C (P<0.01) and vitamin D (P<0.05). Whereas the nutrient density of the males' diets decreased over time for calcium (P<0.05) and vitamin A (P<0.001), iron and riboflavin densities increased in the females' diet (P<0.001). Tracking of energy (MJ day(-1)) and nutrient intakes (expressed per MJ day(-1)) at the individual level was only poor to fair (all kappa<0.25), indicating substantial drift of subjects between the low, medium and high classes of intake with increasing age. CONCLUSIONS: These data suggest that individual dietary patterns exhibited at 15 years of age are unlikely to be predictive of dietary intakes at young adulthood.     

Purification and characterization of a corrinoid-compound in an edible cyanobacterium Aphanizomenon flos-aquae as a nutritional supplementary food

The vitamin B12 concentration of the dried cells of Aphanizomenon flos-aquae was determined by both microbiological method with Lactobacillus delbrueckeii ATCC7830 and chemiluminescence method with intrinsic factor. The Aphanizomenon cells contained 616.3 +/- 30.3 micro g (n = 4) of vitamin B12 per 100 g of the dried cells by the microbiological method. The values determined with the chemiluminescence method, however, were only about 5.3% of the values determined by the microbiological method. A corrinoid-compound was purified from the dried cells and characterized. The purified corrinoid-compound was identified as pseudovitamin B12 (an inactive corrinoid-compound for humans) by silica gel 60 TLC, C18 reversed-phase HPLC, ultraviolet-visible spectroscopy, and 1H NMR spectroscopy. The results suggest that the Aphanizomenon cells are not suitable for use as a vitamin B12 source, especially in vegans.