Icosanoid synthesis as a functional measurement of essential fatty acid requirement.

To assess the need for postoperative vitamin supplements, intakes and nutritional status of thiamin (B1) and vitamin B6 were studied in 18 female gastroplasty patients who received a placebo or different levels of supplemental vitamins. Postoperative erythrocyte transketolase basal (BA) and thiamin pyrophosphate-stimulated (SA) activities and activity coefficients (AC) correlated significantly with B1 intake. Despite a decrease in apotransketolase, low thiamin intakes were associated with increased AC values during the first 3 months. With return to low B1 intakes following repletion during month 4, the AC values remained normal with low total activities. Both alanine (EALT) and aspartate (EAST) aminotransferase apoenzyme levels declined and AC values increased significantly during the first 3 months. Although the EALT-indices were more sensitive to changes in B6 intake than the EAST-indices, the EASTBA and SA correlated most consistently with the intake. Postoperative dietary intakes of both vitamins were inadequate for maintenance of normal activities of these erythrocyte enzymes. Although B1 intake of greater than or equal to 1.0 mg/day was adequate for maintenance of normal thiamin status in most subjects of this study, supplementation with greater than or equal to 1.5 mg/day is prudent even though it may not prevent the early postoperative loss of apotransketolase. Vitamin B6 intake at the current recommended dietary allowance (1.6 mg) was not adequate to maintain coenzyme saturation of the erythrocyte aminotransferases. Marginal intake of other nutrients may have affected the utilization of both thiamin and vitamin B6.     

Vitamin status of pediatric patients receiving long-term peritoneal dialysis

The oral vitamin intakes and concentrations of vitamins in blood of eight children on long-term peritoneal dialysis and six control children were measured. All patients received a daily supplement containing water-soluble vitamins. Serum concentrations of vitamin A, vitamin B-12, ascorbic acid, and folic acid and dialysate concentrations of ascorbic acid were determined. Thiamin and riboflavin were assessed by measuring erythrocyte enzyme activities. Vitamin B-6 was measured as plasma pyridoxal phosphate. Dietary vitamin intake was determined with weighed 3-d food records. The dialysis patients had significantly greater stores of vitamin A, thiamin, riboflavin, pyridoxal phosphate, and folic acid than did the control population (P less than or equal to 0.01). The patients' combined dietary and supplemental intake of all vitamins except ascorbic acid was also significantly greater than the intake of the control group (P less than 0.01). Vitamin supplementation is associated with normal or greater-than-normal values of water-soluble vitamins in pediatric patients receiving long-term peritoneal dialysis.     

Thiamin nutrition and catalysis-induced instability of thiamin diphosphate

Thiamin (vitamin B1) is required in animal diets because it is the precursor of the enzyme cofactor, thiamin diphosphate. Unlike other B vitamins, the dietary thiamin requirement is proportional to non-fat energy intake but there is no obvious biochemical reason for this relationship. In the present communication we show for two enzymes that the cofactor undergoes a slow destruction during catalysis, which may explain the interdependence of thiamin and energy intakes.     

Is vitamin intake by the elderly in The Netherlands precarious?

The elderly are vulnerable to nutritional risks. The vitamin intake (assessed through dietary history) and vitamin status of 539 independently living persons aged 65-79 years and 44 lacto-(ovo)-vegetarian persons aged 65-97 years were evaluated. All respondents were apparently healthy. Compared with the Dutch recommended dietary allowances the intake of vitamins was assessed as adequate except for vitamin B6. The marginal intake of vitamin B6 is reflected in the vitamin B6 status. The prevalence of low 25-hydroxyvitamin D concentrations in plasma is high among elderly people as compared with younger adults (blood donors); the concentration is negatively correlated with age. The vegetarian elderly appeared to be at risk regarding the vitamin B12 status. In conclusion, the average intake of vitamins is assessed as adequate, whereas the intakes of vitamin B6 and vitamin D of Dutch apparently healthy elderly need more attention.     

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.     

Vitamin B6 status assessment in relation to dietary intake in high school students aged 16-18 years

The vitamin B6 status of high school students and its relationship with dietary intake were investigated in this cross-sectional study by face-to-face interview. A total of 157 healthy students aged 16-18 years (eighty-three boys and seventy-four girls) were randomly recruited from two out of nineteen senior high schools in Tainan, Taiwan. Vitamin B6 intakes were calculated from three 24-h dietary records. Direct and indirect vitamin B6 status indicators were measured in plasma, erythrocytes and urine. The anthropometric data, being similar to those of the first Nutrition and Health Survey in Taiwan (1993-1996), showed the normal growth and development of these students. All students except one girl (28.7 nmol/l) had plasma pyridoxal-5'-phosphate (PLP) levels >35 nmol/l, indicating an adequate vitamin B6 status. The mean dietary vitamin B6 intakes of boys and girls were 1.04 (sd 0.29) and 0.96 (sd 0.27) mg/d, respectively. Vitamin B6 status indicators, including plasma PLP, erythrocyte alanine aminotransferase activity coefficient (EALT-AC), aspartate aminotransferase activity coefficient (EAST-AC) and urinary 4-pyridoxic acid (4-PA), were correlated with vitamin B6 intake. Students with adequate values of plasma PLP (>35 nmol/l), EALT-AC ( < 1.25), EAST-AC ( < 1.8) and urinary 4-PA (>3.0 micromol/d) had median intakes of 1.08 and 1.01 mg/d, respectively, for boys and girls. This study suggests that vitamin B6 requirements for boys and girls aged 16-18 years were approximately 1.1 and 1.0 mg/d, respectively.     

Foods, fortificants, and supplements: Where do Americans get their nutrients?

Limited data are available on the source of usual nutrient intakes in the United States. This analysis aimed to assess contributions of micronutrients to usual intakes derived from all sources (naturally occurring, fortified and enriched, and dietary supplements) and to compare usual intakes to the Dietary Reference Intake for U.S. residents aged ≥2 y according to NHANES 2003-2006 (n = 16,110). We used the National Cancer Institute method to assess usual intakes of 19 micronutrients by source. Only a small percentage of the population had total usual intakes (from dietary intakes and supplements) below the estimated average requirement (EAR) for the following: vitamin B-6 (8%), folate (8%), zinc (8%), thiamin, riboflavin, niacin, vitamin B-12, phosphorus, iron, copper, and selenium (<6% for all). However, more of the population had total usual intakes below the EAR for vitamins A, C, D, and E (34, 25, 70, and 60%, respectively), calcium (38%), and magnesium (45%). Only 3 and 35% had total usual intakes of potassium and vitamin K, respectively, greater than the adequate intake. Enrichment and/or fortification largely contributed to intakes of vitamins A, C, and D, thiamin, iron, and folate. Dietary supplements further reduced the percentage of the population consuming less than the EAR for all nutrients. The percentage of the population with total intakes greater than the tolerable upper intake level (UL) was very low for most nutrients, whereas 10.3 and 8.4% of the population had intakes greater than the UL for niacin and zinc, respectively. Without enrichment and/or fortification and supplementation, many Americans did not achieve the recommended micronutrient intake levels set forth in the Dietary Reference Intake.     

Vitamin B6 requirements and recommendations

The principal metabolic function of vitamin B6 is in amino acid metabolism, although the greater part of the body's vitamin B6 is in muscle, associated with glycogen phosphorylase, and the vitamin also has an important role in the actions of steroid hormones. It is usual to calculate vitamin B6 requirements relative to protein intake. An adequate intake to meet the requirements of virtually the whole population is generally considered to be 15 micrograms/g dietary protein. This is the basis of RDAs in most countries, although differences of interpretation and application of the experimental data result in widely differing recommendations from different authorities. Current RDAs range between 1.5 and 2.2 mg/d. A minimum safe intake, below which an individual would have a high probability of deficiency, is 11 micrograms/g dietary protein. Higher intakes are required in pregnancy and lactation (although there are problems in determining the requirement of the infant), and possibly also in the elderly. Average intakes of vitamin B6 in developed countries meet the target of 15 micrograms/g dietary protein, although there is biochemical evidence of inadequate vitamin B6 nutritional status in 10-25 per cent of the population. It is not know whether this has any clinical significance; it is unlikely that normal patterns of food intake would permit a significantly greater average intake of the vitamins without fortification or the use of supplements. There is little evidence that pharmacological doses of vitamin B6 have any beneficial effect. Neurological damage has been reported at extremely high intakes (in excess of 500 mg/d), and even more modest doses (50-100 mg/d) cannot be regarded as being without hazard.     

Ten-year trends in vitamin and mineral intake from fortified food in German children and adolescents

OBJECTIVE: We investigated time trends in consumption patterns, and energy and nutrient intakes (protein, fat, carbohydrates, added sugars, vitamins A, E, C, B1, B2 and B6, niacin, folate, calcium and iron) from fortified food in children and adolescents between 1987 and 1996 in Germany. DESIGN: Mixed longitudinal survey (DONALD study) with 3 d weighed dietary records (n=2062 from 594 subjects), one subject per family per year chosen by random. SETTING: Dortmund (Western Germany) district cohort. SUBJECTS: 285 males, 309 females; mean age 6 y (2-13 y). RESULTS: Almost all children and adolescents consumed fortified food irrespective of the year studied. With the exception of vitamin E, significant time trends in the proportions of nutrient intakes from fortification were observed. The fortification of food with vitamins A, C, B1, B2 and B6 and niacin raised the already adequate intakes from non-fortified food (100% to 150% of reference intake values) by 20-50%. The fortification of food with vitamin E and folate raised the low intakes from non-fortified food (about 50% of reference intake values) to about 80% (folate) and 100% (vitamin E) of the references. Fortification of food with calcium and iron was not significant (<10%), but while total intake of calcium was adequate, total intake of iron remained critical. CONCLUSIONS: Since the nutrient intake of the population of children and adolescents studied is adequate with respect to vitamins A, C, B1, B2 and B6, niacin and calcium, fortification seems inefficient, while fortification of food with vitamin E and folate, but not iron, improves an inadequate intake. SPONSORSHIP: The DONALD study is supported by the German Federal Ministry of Health and the North-Rhine-Westphalian Ministry of Science and Research. European Journal of Clinical Nutrition (2000) 54, 81-86     

Nutrient intake and vitamin status of healthy French vegetarians and nonvegetarians

The status of thiamin, riboflavin, folate, and vitamins B-6, B-12, C, A, D, and E was investigated in 37 middle-aged and healthy French vegetarians by means of a dietary survey and biochemical studies. Values were compared with those of a group of nonvegetarians. Unsatisfactory intakes of vitamin B-6 were observed: vitamin B-6 intake as a percentage of the French Recommended Dietary Allowances was approximately 66% for vegetarians and approximately 58% for nonvegetarians. Vegetarians had a higher mean intake of thiamin, riboflavin, and vitamins C, A, D, and E than did nonvegetarians. Vegetarians did not have a higher risk rate for a biochemical vitamin deficiency of thiamin, riboflavin, folates, and vitamins B-6, C, A, and E than the nonvegetarians. The percentage of subjects assessed as abnormal by blood vitamin concentrations was higher in vegetarians for vitamin B-12 (serum vitamin B-12) and vitamin D, which indicated a higher risk for a deficiency of vitamins B-12 and D in this group.     

Vitamin contents in rat milk and effects of dietary vitamin intakes of dams on the vitamin contents in their milk

Studies of factors that affect milk vitamin contents are important. We investigated the vitamin contents in rat milk and the effects of dietary vitamin intakes of dams on the vitamin contents in their milk. A low-vitamin diet (0.2%) and a high-vitamin diet (4.0%) based on a diet containing 1% AIN-93-VX (normal diet) was given to female rats from pregnancy to lactation. Regarding the effects of the vitamin intakes, the concentrations of vitamins B(1), B(2), B(6), B(12) and E were decreased with the low-vitamin diet, but were not increased with the high-vitamin diet. The concentrations of niacin, pantothenic acid and biotin were not decreased with the low-vitamin diet, but were increased with the high-vitamin mixture diet. The folate concentration remained constant regardless of the intake of folate. These findings clearly indicate that the levels of certain vitamins in milk are easily affected by the dietary vitamin intakes.     

Plasma vitamin B6 concentrations in Nigerian adolescents

Vitamin B6 status was assessed from dietary and plasma vitamin B6 concentration using Saccharomyces uvarum as test organism, and erythrocyte alanine amino transferase activity (E-ALAT). The subjects participating in the study were 72 males and 30 females (aged 10-18 years) who resided in a boarding institution. Mean daily dietary vitamin B6 and protein intakes were 1.56 +/- 0.42 mg and 63.0 +/- 9.6 g respectively. The corresponding mean plasma vitamin B6 concentration was 194 +/- 44.2 nmol/l. Neither age, sex nor menarche had significant effect (P less than 0.05) on plasma vitamin B6 concentration of these adolescents. Dietary vitamin B6 but not protein intake correlated with plasma vitamin B6 (r = 0.3076, P less than 0.002). However, low dietary vitamin B6/protein ratio (less than 0.02 mg/g) was not reflected in plasma vitamin B6 concentration, but low plasma vitamin B6 concentration (120-179 nmol/l) corresponded to low E-ALAT activity after in vitro addition of pyridoxal phosphate (E-ELAT 16 per cent). A stimulation above 25 per cent, 16-25 per cent and below 16 per cent was used as an indicator of poor, marginal and adequate vitamin B6 status, respectively. Based on these criteria 30.7 per cent, 17.8 per cent and 51.5 per cent of subjects, with corresponding mean plasma vitamin B6 of 150 +/- 28.4, 192 +/- 8.5 and 237 +/- 18.7 nmol/l are of deficient, marginal and adequate vitamin B6 status, respectively.     

Thiamin, riboflavin, and vitamins B-6 and C: impact of combined restricted intake on functional performance in man

A double-blind study of combined restriction of thiamin, riboflavin, and vitamins B-6 and C was carried out with 23 healthy males. During 8 wk of low vitamin intake, 12 deficient subjects consumed daily a diet of normal food products, providing maximally 32.5% of the Dutch Recommended Dietary Allowances (RDA) for thiamin, riboflavin, vitamins B-6 and C. Other vitamins were supplemented at twice the RDA. Eleven control subjects consumed the same diet but with a supplementation of twice the RDA of all vitamins. In deficient subjects blood vitamin levels, urinary vitamin excretion, and erythrocytic enzyme activities decreased; in vitro enzyme stimulation increased. Vitamin depletion had no ill effects on health, physical activity, and mental performance. A significant decrease was observed in aerobic power (VO2max) and onset of blood lactate accumulation (p less than 0.001) of 9.8 and 19.6%, respectively. A combined restricted intake of thiamin, riboflavin, and vitamins B-6 and C causes a decrease in physical performance within a few weeks.     

Nutrient supplement use by healthy elderly

As part of a nutritional status survey of 691 non-institutionalized men and women aged 60 years and older, supplement use was reported by 45% of the males and 55% of the females. Supplement use was more prevalent in females than males at each age decade. Vitamins C and E were the most commonly used supplements. Mean dietary nutrient intakes were calculated from a 3-day food diary. The percentage of dietary intakes falling below 2/3 1980 Recommended Dietary Allowance (RDA) was comparable for users and non-users of supplements. Use of supplements markedly decreased the proportion of subjects with inadequate nutrient intake (using a 2/3 RDA criterion), particularly for vitamins B6, B12, and D, folic acid, and calcium. However, for both males and females, potentially excessive intake levels (10 times the RDA) of thiamin, vitamin A, and vitamin E supplementation were observed.     

Nutrient supplement use by healthy elderly.

As part of a nutritional status survey of 691 non-institutionalized men and women aged 60 years and older, supplement use was reported by 45% of the males and 55% of the females. Supplement use was more prevalent in females than males at each age decade. Vitamins C and E were the most commonly used supplements. Mean dietary nutrient intakes were calculated from a 3-day food diary. The percentage of dietary intakes falling below 2/3 1980 Recommended Dietary Allowance (RDA) was comparable for users and non-users of supplements. Use of supplements markedly decreased the proportion of subjects with inadequate nutrient intake (using a 2/3 RDA criterion), particularly for vitamins B6, B12, and D, folic acid, and calcium. However, for both males and females, potentially excessive intake levels (10 times the RDA) of thiamin, vitamin A, and vitamin E supplementation were observed.     

The vitamin B6 requirement in oral contraceptive users. I. Assessment by pyridoxal level and transferase activity in erythrocytes.

Eight college-age women using estrogen-containing oral contraceptives (OC) were fed a low vitamin B6 diet (0.36 mg/day) for 42 days. During the first 10 days (adjustment period) the diet was supplemented with 1.7 mg pyridoxine hydrochloride bringing the total intake to 2.06 mg/day. Following depletion, repletion was done in three consecutive steps: intakes of 0.96, 1.56, and 5.06 mg were consumed for 8, 9, and 7 days, respectively. Continuous 24-hr urine collections were made throughout the study and fasting blood samples were drawn periodically. Vitamin B6 nutriture was assessed by erythrocyte pyridoxal level, erythrocyte alanine aminotransferase and erythrocyte aspartic aminotransferase activity; and stimulation of these enzyme systems with pyridoxal phosphate. Results were compared with data obtained from non-OC users who consumed a similar diet. The data obtained suggest that 0.96 mg vitamin B6 was not adequate to meet the needs of OC users. Predepletion levels had been reached in almost all subjects at an intake of 1.5 mg/day. Assessed by the parameters studied, an intake between 1.5 and 5.0 mg/day of vitamin B6 was adequate to meet the needs of OC users; this compares with 1.5 mg/day previously suggested for the nonuser.     

Vitamins E, C, thiamin, riboflavin and vitamin B-6 status of institutionalized elderly including the effects of supplementation

A double-blind placebo trial of vitamins E, C, thiamin, riboflavin, and vitamin B-6 has been undertaken in 84 elderly institutionalized subjects (31 men and 53 women, aged>65y). Five-day records and biochemical determinations were used to assess vitamin status. The 1992 French Recommended Dietary Allowance (FRDA) and the RDA set in the United States were used to assess adequacy of intake. At baseline, vitamin status as assessed by dietary information and biochemical indices appeared deficient except for riboflavin (in females only). At the end of one month treatment with moderate doses of vitamins (100–400% FRDA), serum vitamin E (only in males), serum ascorbate, and erythrocyte thiamin pyrophosphate levels had increased significantly. A significant improvement was also effected in erythrocyte transketolase, glutathione reductase, aspartate aminotransferase activation coefficients. This was accompanied by a significant decrease in the number of subjects with deficient values. However, the percentage of subjects with biochemical deciciency for thiamin, riboflavin (only in males), and vitamin B-6 remained>5%.     

Vitamin requirements of the elderly

In general, low dietary intakes can account for much of poor vitamin nutriture reported among various elderly populations. Despite problems in assessing vitamin nutriture in the elderly, the 1980 RDAs for thiamin, riboflavin, and ascorbic acid seem appropriate for those populations. However, RDAs for vitamin A and folate may be too high and the RDAs for vitamin D, vitamin B-6, and vitamin B-12 may be too low, due to specified age-related changes in the metabolism of these vitamins. For vitamin E, vitamin K, niacin, biotin, and pantothenic acid, the data is conflicting and/or insufficient to make a judgment about the appropriateness of the RDAs or to estimate safe and adequate daily intakes for the elderly.     

Nutritional value of daily diets prepared in several regions of the country. Part V. Value of group b vitamins]

Studies of the content of group B vitamins: thiamin, riboflavin, niacin and vitamin b6 in daily diets of manual and mental workers with medium income were carried on. The diets were prepared for five regions of the country (Warszawa, Lublin, Olsztyn, Poznań, Wroc?aw) under laboratory conditions. These diets contained respectively: thiamin 1.17 and 1.11 mg, riboflavin 1.48 and 1.55 mg; niacin 11.3 and 10.2 mg and vitamin B6 1.50 and 1.21 mg per day. According to the studies the realization of daily requirements by these diets for thiamin were met 82 and 98%, for niacin 62 and 65%, and for vitamin B6 79 and 64%. The comparison of the presently studied diets with the ones from 1973, 1980 and 1981 showed that the content of niacin and vitamin B6 intakes systematically decrease. There were no considerable differences in the contents of group B vitamins between diets prepared in all five regions of Poland.