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The comparative impact of iron, the B-complex vitamins, vitamins C and
E, and selenium on diarrheal pathogen outcomes relative to the impact
produced by vitamin A and zinc.Nutr
Rev. 2007 May;65(5):218-32.
Micronutrient
supplementation offers one of the most cost-effective means of
improving the health and survival of children in developing countries.
However, the effects of supplementation with single micronutrients on
diarrhea are not always consistent, and supplementation with
multi-micronutrient supplements can have negative effects. These
inconsistencies may result from the failure to consider the diverse
etiological agents that cause diarrhea and the unique effects each
micronutrient has on the immune response to each of these agents. This
review examines the separate effects that supplementation with the
B-complex vitamins, vitamin C, vitamin E, selenium, and iron have on
diarrheal disease-related outcomes. Supplementation with iron may
increase the risk of infection by invasive diarrheal pathogens, while
supplementation with the remaining micronutrients may reduce this
risk. These differences may be due to distinct regulatory effects each
micronutrient has on the pathogen-specific immune response, as well as
on the virulence of specific pathogens. The findings of these studies
suggest that micronutrient supplementation of children must take into
account the pathogens prevalent within communities as reflected by
their diarrheal disease burdens. The effectiveness of combining
multiple micronutrients into one supplement must also be reconsidered.
Vitamin B6, B12, and folic acid supplementation and
cognitive function: a systematic review of randomized trials.Arch
Intern Med. 2007 Jan 8;167(1):21-30.
BACKGROUND:
Despite their important role in cognitive function, the value of B
vitamin supplementation is unknown. A systematic review of the effect
of pyridoxine hydrochloride (hereinafter "vitamin B(6)"),
cyanocobalamin or hydroxycobalamin (hereinafter "vitamin B(12)"), and
folic acid supplementation on cognitive function was performed.
METHODS: Literature search conducted in MEDLINE with supplemental
articles from reviews and domain experts. We included English language
randomized controlled trials of vitamins B(6) and/or B(12) and/or
folic acid supplementation with cognitive function outcomes. RESULTS:
Fourteen trials met our criteria; most were of low quality and limited
applicability. Approximately 50 different cognitive function tests
were assessed. Three trials of vitamin B(6) and 6 of vitamin B(12)
found no effect overall in a variety of doses, routes of
administration, and populations. One of 3 trials of folic acid found a
benefit in cognitive function in people with cognitive impairment and
low baseline serum folate levels. Six trials of combinations of the B
vitamins all concluded that the interventions had no effect on
cognitive function. Among 3 trials, those in the placebo arm had
greater improvements in a small number of cognitive tests than
participants receiving either folic acid or combination B-vitamin
supplements. The evidence was limited by a sparsity of studies, small
sample size, heterogeneity in outcomes, and a lack of studies that
evaluated symptoms or clinical outcomes. CONCLUSION: The evidence does
not yet provide adequate evidence of an effect of vitamin B(6) or
B(12) or folic acid supplementation, alone or in combination, on
cognitive function testing in people with either normal or impaired
cognitive function.
Water-soluble vitamins.J
AOAC Int. 2006 Jan-Feb;89(1):285-8
Simultaneous
Determination of Vitamins.--Klejdus et al. described a simultaneous
determination of 10 water- and 10 fat-soluble vitamins in
pharmaceutical preparations by liquid chromatography-diode-array
detection (LC-DAD). A combined isocratic and linear gradient allowed
separation of vitamins in 3 distinct groups: polar, low-polar, and
nonpolar. The method was applied to pharmaceutical preparations,
fortified powdered drinks, and food samples, for which results were in
good agreement with values claimed. Heudi et al. described a
separation of 9 water-soluble vitamins by LC-UV. The method was
applied for the quantification of vitamins in polyvitaminated premixes
used for the fortification of infant nutrition products. The
repeatability of the method was evaluated at different concentration
levels and coefficients of variation were <6.5%. The concentrations of
vitamins found in premixes with the method were comparable to the
values declared. A disadvantage of the methods mentioned above is that
sample composition has to be known in advance. According to European
legislation, for example, foods might be fortified with riboflavin
phosphate or thiamin phosphate, vitamers which are not included in the
simultaneous separations described. Vitamin B2.--Viñas et al.
elaborated an LC analysis of riboflavin vitamers in foods. Vitamin B2
can be found in nature as the free riboflavin, but in most biological
materials it occurs predominantly in the form of 2 coenzymes, flavin
mononucleotide (FMN) and flavin-adenine dinucleotide (FAD). Several
methods usually involve the conversion of these coenzymes into free
riboflavin before quantification of total riboflavin. According to the
authors, there is growing interest to know flavin composition of
foods. The described method separates the individual vitamers
isocratically. Accuracy of the method is tested with 2 certified
reference materials (CRMs). Vitamin B5.-Methods for the determination
of vitamin B5 in foods are limited because of their low sensitivity
and poor selectivity. Pakin et al. proposed a post-column
derivatization of pantothenic acid as a fluorescent compound and used
this principle in a specific and sensitive method for the
determination of free and bound pantothenic acid in a large variety of
foods. A French laboratory invited European laboratories to
participate in a series of collaborative studies for this method,
which will be carried out in 2005/2006. A more sophisticated method
was described by Mittermayer et al. They developed an LC-mass
spectrometry (LC/MS) method for the determination of vitamin B5 in a
wide range of fortified food products. Application of the method to
various samples showed consistent results with those obtained by
microbiology. Vitamin B6.-Method 2004.07, an LC method for the
analysis of vitamin B6 in reconstituted infant formula, was published
by Mann et al. In contrast with this method, which quantifies vitamin
B6 after converting the phosphorylated and free vitamers into
pyridoxine, Viñas et al. published an LC method which determines 6
vitamin B6 related compounds, the 3 B6 vitamers, their corresponding
phosphorylated esters, and a metabolite. Accuracy was determined using
2 CRMs. Results were within the certified ranges. Vitamin C.-Franke et
al. described an extensive study to vitamin C and flavonoid levels of
fruits and vegetables consumed in Hawaii. Vitamin C was determined by
measuring ascorbic acid in its reduced state by LC and coulometric
detection along with UV absorbance detection at 245 nm. No attempts
were made to assess levels of dehydroascorbic acid. Most recent
research revealed that cell uptake of dehydroascorbic acid is unlikely
to play a major role, which may explain the very low vitamin C
activity of orally administered L-dehydroascorbic acid in rats. The
food levels found by Franke et al. are variably lower, higher, or
equal in comparison to other studies. Iwase described a method for the
determination of ascorbic acid in foods using L-methionine for the
pre-analysis sample stabilization. Electrochemical detection was used
for the quantification. Traditionally, metaphosphoric acid was proven
to be a useful dissolving agent for the determination of ascorbic
acid. However, it dissolves in water very slowly, it is hygroscopic,
and accurate weighing is not easy. Adjustment at pH 2-3 takes a long
time. It appeared to be possible to replace metaphosphoric acid by
0.2% phosphoric acid. Methionine played an important role on the
stability of ascorbic acid. The method seemed to be applicable to the
routine analysis of ascorbic acid in foods. Folic
Acid.-Microbiological analysis of total folate in foods is often
considered as the golden standard compared to other methods based on,
for example, LC. Koontz et al. showed results of total folate
concentrations measured by microbiological assay in a variety of
foods. Samples were submitted in a routine manner to experienced
laboratories that regularly perform folate analysis fee-for-service
basis in the United States. Each laboratory reported the use of a
microbiological method similar to the AOAC Official Method for the
determination of folic acid. Striking was, the use of 3 different pH
extraction conditions by 4 laboratories. Only one laboratory reported
using a tri-enzyme extraction. Results were evaluated. Results for
folic acid fortified foods had considerably lower between-laboratory
variation, 9-11%, versus >45% for other foods. Mean total folate
ranged from 14 to 279 microg/100 g for a mixed vegetable reference
material, from 5 to 70 microg/100 g for strawberries, and from 28 to
81 microg/100 g for wholemeal flour. One should realize a large
variation in results, which might be caused by slight modifications in
the microbiological analysis of total folate in foods or the analysis
in various (unfortified) food matrixes. Furthermore, optimal
combination of enzymes and reaction conditions may vary depending on
the composition of the food. Padrangi and Laborde showed recently that
treatment with alpha-amylase had no significant effect on measured
folate in spinach, although addition of protease significantly
increased the release of folate. LC/MS applications gain increasing
attention because of their specificity. Rychlik used stable isotope
dilution assays for the determination of the folate content of
broccoli and bread. Compared to data in the literature and food data
bases, amounts were significantly lower. Pawlosky et al., however,
found comparable values for 5-methyltetrahydrofolic acid and folic
acid by HPLC analysis with fluorescent detection and HPLC/MS. Among
samples analyzed were CRMs and broccoli. Besides folic acid, other
water-soluble vitamins were also determined by LC/MS/MS by Leporati et
al. The method was applied to the quantitative analysis of the natural
content of vitamins in typical Italian pasta samples, as well as in
fortified pasta samples produced for the U.S. market. Biotin.-A paper
from Staggs et al. included the assertion that existing biotin data in
food composition tables are inaccurate because the majority are based
on bioassays with all relevant disadvantages. Data in most cases are
overestimated with consequences for recommendations for dietary biotin
intake. An HPLC/avidin-binding assay was used to analyze 87 foods to
support the hypothesis mentioned.
Intestinal
absorption of water-soluble vitamins.Proc
Soc Exp Biol Med. 1996 Jul;212(3):191-8.
Vitamin utility
is a scientific/medical topic that appears to be pursued as ardently
by the lay public as by scientists and medical practitioners. A group
of epidemiologists evaluates the effects on health of vitamin intake
in the natural diet and by supplementation. The role in ocular
disease, cancer of the breast or colon, and cardiovascular disease are
a few of the concerns. The results and recommendations concerning
dietary vitamin intake will likely continue to change. However, the
processes by which dietary vitamins are delivered from intestinal
chyme to the blood are more certain. The concept of homeostasis might
apply to various of the vitamins as it does to minerals, water, etc.
This review will discuss some common methods used to study vitamin
absorption and the proposed mechanisms of absorption, and will
conclude with a section about dietary regulation.
Blood vitamin status (B1, B2, B6, folic acid and B12) in patients with
alcoholic liver disease.Int
J Vitam Nutr Res. 1982;52(3):266-71.
Blood vitamin
status (B1, B2, B6, folic acid and B12) was assessed in 41 patients (M
= 39; F = 2) with alcoholic liver disease. Biochemical evidence of
thiamine deficiency was observed in all groups of patients. Deficiency
of riboflavin was detected in patients with histologically normal
liver but not in other groups. All the groups were found to be
deficient in pyridoxal-5-phosphate--the active form of vitamin B6
(pyridoxine). Serum folate was decreased in all groups except in those
with alcoholic hepatitis: red cell folate was, of course within normal
limits in all the groups. Vitamin B12 levels were within normal limits
in all groups except the cirrhotic one where it was raised. Clinico-biochemical
implications of the findings are discussed. Biochemical changes in
blood vitamin status may precede clinical manifestations of a disease
process and may have prognostic value.
B complex
vitamin patterns in geriatric and young adult inpatients with major
depression.J
Am Geriatr Soc. 1991 Mar;39(3):252-7.
This
study compared the B complex vitamin status at time of admission of 20
geriatric and 16 young adult non-alcoholic inpatients with major
depression. Twenty-eight percent of all subjects were deficient in B2
(riboflavin), B6 (pyridoxine), and/or B12 (cobalamin), but none in B1
(thiamine) or folate. The geriatric sample had significantly higher
serum folate levels. Psychotic depressives had lower B12 than did
non-psychotic depressives. Poorer blood vitamin status was not
associated with higher scores on the Hamilton Depression Rating Scale
or lower scores on the Mini-Mental State Examination in either age
group. The data support the hypothesis that poorer status in certain B
vitamins is present in major depression, but blood measures may not
reflect central nervous system vitamin function or severity of
affective syndromes as measured by the assays and scales in the
present study.
Brief communication.
Vitamin B1, B2, and B6 augmentation of tricyclic antidepressant
treatment in geriatric depression with cognitive dysfunction.J
Am Coll Nutr. 1992 Apr;11(2):159-63.
This was
a 4-week randomized placebo-controlled double-blind study to assess
augmentation of open tricyclic antidepressant treatment with 10 mg
each of vitamins B1, B2, and B6 in 14 geriatric inpatients with
depression. The active vitamin group demonstrated significantly better
B2 and B6 status on enzyme activity coefficients and trends toward
greater improvement in scores on ratings of depression and congnitive
function, as well as in serum nortriptyline levels compared with
placebo-treated subjects (Ss). Without specific supplementation, B12
levels increased in Ss receiving B1/B2/B6 and decreased in placebo Ss.
These findings offer preliminary support for further investigation of
B complex vitamin augmentation in the treatment of geriatric
depression.
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