The purposes of the research presented in this thesis were: (1)
to determine the precision with which it is possible to measure
changes in vitamin B6 compounds in the blood and urine following
oral doses of levels of vitamin B6 (as pyridoxine) which are in the
range of the normal...
Bioavailability (BA) of vitamin B6 (B-6) from foods may be
limited. The knowledge of the BA of B6 from food is important in
that this would help to understand if the B6 present in the diet of
individuals will meet the requirements for this vitamin.
The purpose of this study...
The purpose of this study was, first, to investigate whether there
is a vitamin B-6 requirement for carnitine synthesis and, second, to investigate
the effect of fasting on vitamin B-6 metabolism. An experimental
group of 72 rats (6 per group) were fed either a vitamin B-6 deficient
diet (-B6) (ad...
The effect of vitamin B-6 (VB6) deficiency in mice on host
susceptibility to primary and secondary Moloney-sarcoma virus
(MSV)-induced tumor growth, cytotoxic activities of T cells,
antibodies and natural killer (NK) cells, and phagocytosis by
macrophages was examined. Five- to six-week old female C57B1/6 mice
were fed 20% casein diets...
To investigate the responses of healthy adult women to two
levels of vitamin B-6, a seven week two-part experiment was conducted
with five young adults and eight middle-aged subjects. During the
four unsupplemented weeks, dietary vitamin B-6 was 2.3-2.4 mg/day.
In the final three weeks, the same diet was supplemented...
Previous studies have found that smoking may have a negative effect on
vitamin B-6 indices and have demonstrated a possible association between smoking
and depressed plasma pyridoxal-5'-phosphate (PLP) concentration. Individuals with
plasma PLP values below the adequate level of 30 nmoles/L might benefit from
consumption of vitamin B-6 supplements, but...
Previous studies suggest that vitamin B-6 supplementation can alter fuel metabolism during
exercise and plasma amino acid levels at rest. To examine the effect of vitamin B-6
supplementation on plasma fuel substrates and amino acid levels during exercise, five trained
males (age: 29±7; V0₂ max: 54.7±6.2 ml/kg/min) performed two separate...
Four studies were conducted to evaluate the effect of varying levels of vitamin
B-6 (B6), protein and pyridoxine glucoside (PNG) on B6 status and requirements of
women. In the first two studies, women were fed a constant protein diet and vitamin
B-6 intakes of 0.84 to 2.39 mg/d during 10-...
Trained male cyclists (6 in study 1, 5 in study 2) cycled to exhaustion (EXH) at
75% of VO₂ max twice; once in the non-supplemented (NS) state and once in the vitamin
B-6 (B-6)(20 mg PN) supplemented (S) state. The diet contained 2.3 mg B-6 in study 1
and 1.9...
Two studies were conducted to determine the effect of varying vitamin B-6 (B- 6) status on lymphocyte mitogenic response and pyridoxal 5'-phosphate (PLP) concentration in peripheral blood mononuclear cells (PBMC) in young women. In the first study, women were fed 1 mg/d for the first week and 1.5, 2.1 and...
Serine transhydroxymethylase (STHM), a pyridoxal 5'-
phosphate requiring enzyme is indirectly involved in
pyrimidine deoxynucleotide metabolism. A decrease in the
activity of this enzyme could lead to altered deoxycytidine
(dC) metabolism. This study was undertaken to determine if
a vitamin B-6 deficiency affects dC metabolism. The effect
of a vitamin...
In two studies we tested the effect of vitamin B-6
(B-6) intake on in vitro lymphocyte, proliferation and IL-2
production in healthy young women. In Study I, 6 women were
fed a constant diet containing 0.84 mg (4.96 μmols) of B-6
for 12 d, and 1.24 mg (7.33 μmols) and...
The purpose of this study was to examine the effect of extreme exercise on vitamin B-6
metabolism and urea nitrogen. Nine men and five women completed two 5-day trials; Trial 1
(T1) included a 50-km ultramarathon on day 4 and during Trial 2 (T2) subjects were "inactive"
on day 4....
Exercise increases B-vitamin (B6, B12, folate) dependent metabolic reactions, especially those related to energy production and the rebuilding and repairing of muscle tissue. These same B-vitamins are also important in maintaining low blood levels of homocysteine (Hcy), a cardiovascular disease (CVD) risk factor. Hcy levels rise when the metabolism of...
The aim of this study was to investigate the vitamin B-6 status of Saudi adult males and compare the status between rural and urban subjects. Fifty-one adult male subjects were recruited from urban (n=31) and rural (n=20) populations of Riyadh. These subjects were reclassified to cigarette smokers (n=19), water pipe...