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ANTIOXIDANT VITAMIN AND
MINERAL SUPPLEMENTATION AND PROSTATE CANCER PREVENTION IN
THE
SU.VI.MAX TRIAL
Meyer F, et al.
Int J Cancer 2005 Aug 20;116(2):182-6.
Randomized trials have shown
that supplementation with selenium or vitamin E is
associated with a reduction of
prostate cancer risk. We assess whether a supplementation
with low doses of antioxidant vitamins and minerals could
reduce the occurrence of prostate cancer and influence
biochemical markers. The SU.VI.MAX trial comprised 5,141 men
randomized to take either a placebo or a supplementation
with nutritional doses of vitamin C, vitamin E, betacarotene,
selenium and zinc daily for 8 years. Biochemical markers of
prostate cancer risk such as prostate-specific antigen (PSA)
and insulin-like growth factors (IGFs) were measured on
plasma samples collected at enrollment and at the end of
follow-up from 3,615 men. During the follow-up, 103 cases of
prostate cancer were diagnosed. Overall, there was a
moderate nonsignificant reduction in prostate cancer rate
associated with the supplementation. However, the effect
differed significantly between men with normal baseline PSA
(<3 microg/L) and those with elevated PSA.
Among men with normal PSA, there was a marked statistically
significant reduction in the rate of prostate cancer for
men receiving the supplements. In men with elevated PSA at
baseline, the supplementation was associated with an
increased incidence of prostate cancer of borderline
statistical significance. The supplementation had no effect
on PSA or IGF levels. The findings support the hypothesis
that chemoprevention of prostate cancer can be achieved with
nutritional doses of antioxidant vitamins and minerals.
EFFECT OF THE JOINT ADMINISTRATION OF
SELENIUM AND VITAMIN E IN COMBINATION WITH REGULAR
AEROBIC EXERCISE ON MARKERS OF LIPID PEROIDATION AND
GLUTATHIONE PEROXIDASE IN DIABETIC RATS
Kim HT
Int J Sport Nutr Exerc Metab 2005 Jun;15(3):266-78.
Researchers investigated the
effect of long-term treatment (6 wk) with selenium and
vitamin E, in combination with aerobic exercise
training, on malondialdehyde (MDA), oxidized low-density
lipoprotein (ox-LDL), and glutathione peroxidase (GPx)
in STZ-induced diabetic rats. The rats were assigned
randomly to one of three treatment groups (n = 12 per
group); 1.) exercise group (EX), 2.) selenium/vitamin
E/exercise group (SVE), and 3.) selenium/vitamin E group
(SV). To estimate the acute effect of exercise, a 30
minute endurance exercise was used. The MDA
concentration was significantly lower in the SVE. The
ox-LDL was significantly lower in the SVE and SV. The
hepatic concentrations of selenium and vitamin E were
significantly higher in the SVE. These results indicate
that the increase in MDA is mildly attenuated in rats
that were aerobically trained. Moreover, the joint
administration of selenium and vitamin E with or without
exercise training reduces the levels of ox-LDL.
STATUS OF INTRACELLULAR AND
EXTRACELLULAR MAGNESIUM CONCENTRATION IN PATIENTS WITH
CARDIAC SYNDROME X
Guo H, et al.
Acta Cardiol 2005 Jun;60(3):259-63.
This study sought to clarify the
differences of intracellular and extracellular magnesium
levels in patients with cardiac syndrome X. They evaluated
the intracellular-and gender-matched disorder-free control
subjects (group B). Levels of magnesium were determined in
serum, urine, erythrocytes, and the 24-hour magnesium
retention rate was calculated by a magnesium loading test.
Group A showed a higher 24-hour magnesium retention rate
(49.8 +/- 1.3% vs. 32.6 +/- 7.5%, p<0.05) and a lower
intracellular concentration of magnesium in erythrocytes
than group B (3.7 +/- 1.4 vs. 5.6 +/- 1.l3 fg/cell, p<0.05),
demonstrating the presence of magnesium deficiency in group
A. There were no significant differences in the serum
concentration of magnesium between groups A and B (0.87 +/-
0.23 vs. 0.83 +/- 0.15 mmol/l). This study demonstrated that
the intracellular magnesium level decreased in patients with
cardiac
syndrome X.
LOWER SERUM MAGNESIUM LEVELS ARE
ASSOCIATED WITH MORE RAPID DECLINE OF REMAL FUNCTION IN
PATIENTS WITH DIABETES MELLITUS TYPE 2
Pham Pc, et al.
Clin Nephrol 2005 Jun;63(6):429-36.
Hypomagnesemia has been
implicated in adversely affecting diabetic complications.
This is a retrospective study designed to determine whether
there is any association between serum magnesium
concentration [Mg2+] and the rate of renal function
deterioration, as determined by the slope of serum
creatinine reciprocals versus time (1/SCr-vs-t), in patients
with diabetes mellitus type 2 (DM2). DM2 patients without
known kidney disease seen at Olive View-UCLA Medical Center
for any reason during January-March 2001 were included. For
each patient, all available data from our electronic
database for [Mg2+], hemoglobin A(1C) (HbA(1C), serum
creatinine (SCr), lipid profiles, routine urinary analysis,
as well as history of hypertension and pharmacy profiles
were retrieved. The average of all parameters obtained and
linear regression analyses for the slope of 1/SCr-vs-t plot
were performed for each patient. Patients were stratified by
gender and divided into four groups based on increasing
[Mg2+].
Correlations between each parameter including the slope of
1/SCr-vs-t and the four magnesium groups were analyzed.
RESULTS: 252 males and 298 females with a mean follow-up of
62.6 +/- 22.5 months were included. Patients belonging to
lower [Mg2+] groups for both genders had significantly worse
slopes of 1/SCr-vs-t plot independent of the presence of
hypertension and use of ACEI/ARB, diuretics, HMP-CoA enzyme
inhibitors or aspirin. In a multivariate regression analysis
controlling for age, HbA(1C) and various components of the
lipid profile, [Mg2+] remained an independent predictor for
the slope of 1/SC4-vs-t. A trend for worse proteinuria bsed
on routine urinary analysis was observed among patients
belonging to the lowest [Mg2+] group. The researchers
concluded that lower [Mg2+] is associated with a faster
renal function deterioration rate in DM2 patients.
SELENIUM AND ENDOCRINE SYSTEMS
Beckett GH and Arthur JR.
J Endocrinol 2005 Mar;184(3):455-65.
The trace element selenium (Se) is capable of exerting
multiple actions on endocrine systems by modifying the
expression of at least 30 selenoproteins, many of which have
clearly defined functions. Well-characterized selenoenzymes
are the families of glutathione peroxidases (GPXs),
thioredoxin reductases (TRs) and iodothyronine deiodinases
(Os). These selenoenzymes are capable of modifying cell
function by acting as antioxidants and modifying redox
status and thyroid hormone metabolism. Se is also involved
in cell growth, apoptosis and modifying the action of cell
signaling systems and transcription factors. During thyroid
hormone synthesis GPX1, GPX3 and TR1 are up-regulated,
providing the thyrocytes with considerable protection from
peroxidative damage.
Thyroidal D1 in rats and both D1 and D2 in humans are also
up-regulated to increase the production of bioactive
3,5,3'-triiodothyronine (T3). In the basal state, GPX3 is
secreted into the follicular lumen where it may
down-regulate thyroid hormone synthesis by decreasing
hydrogen peroxide concentrations. The deiodinases are
present in most tissues and provide a mechanism whereby
individual tissues may control their exposure to T3.
Selenium is also able to modify the immune response in
patients with autoimmune thyroiditis. Low sperm production
and poor sperm quality are consistent features of
selenium-deficient animals. The pivotal link between
selenium, sperm quality and male fertility is GPX4 since the
enzyme is essential to allow the production of the correct
architecture of the midpiece of spermatozoa. Selenium also
has insulin-mimetic properties, an effect that is probably
brought about by stimulating the tyrosine kinases involved
in the insulin signaling cascade. Furthermore, in the
diabetic rat, selenium not only restores glycaemic control
but it also prevents or alleviates the adverse effects that
diabetes has on cardiac, renal and platelet function.
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