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ZINC PLUS BETA-CAROTENE SUPPLEMENTATION
OF PREGNANT WOMEN IS SUPERIOR TO BETACAROTENE
SUPPLEMENTATION ALONE IN IMPROVING VITAMIN A STATUS IN BOTH
MOTHERS AND
INFANTS.
Dijkhuizen MA, et al.
Am J Clin Nutr, 2004, 80:1299-1307.
There is a high incidence of vitamin A, iron, and zinc
deficiencies in the women and infants of developing
nations. This study was performed to determine whether
supplementation with iron and folic acid plus betacarotene
or zinc or both, during pregnancy can improve the
micronutrient status of the mothers and infants
after birth. In this randomized, double-blind, controlled
trial (170 pregnant women), all of the mothers
received iron and folic acid (control), while groups of them
received the control nutrients plus beta-carotene
or zinc or both. Micronutrient status was evaluated at 1
month and 6 months after delivery. The plasma
retinol levels were higher in the women who received zinc
during pregnancy than in the women who did
not. The women receiving beta-carotene plus zinc had the
best retinol scores, with the frequency of vitamin
A deficiency reduced by 30% compared to the other 3 groups.
The breast milk beta-carotene levels were
higher in all who received beta-carotene supplementation,
but breast milk retinol levels were higher only in
the women who received beta-carotene plus zinc. The
researchers concluded that zinc supplementation
during pregnancy improves vitamin A status of mothers and
infants postpartum, indicating a role for zinc in
vitamin A metabolism.
EFFECT OF
HABITUAL DIETARY CALCIUM INTAKE ON CALCIUM SUPPLEMENTATION
IN 12-14
YEAR OLD GIRLS.
Melgaard C, Thomsen BL, and Michaelsen KF.
Am J Clin Nutr 2004;80:1422-1427.
The effect of calcium supplementation on bone accretion may
depend on habitual dietary calcium intake so
that supplementation mainly affects individuals with low
habitual calcium intakes. This randomized,
double-blind, placebo-controlled, 1-year calcium
intervention study attempts to evaluate whether the impact
of calcium supplementation on whole body bone mineral
accretion is dependent on the habitual level of
dietary calcium intake. In the study, 12-14 year old girls
were selected from a larger group according to
habitual calcium intake. One group had a habitual calcium
intake of 1000-1307 mg/d, and the second group
had a habitual intake for calcium of less than 713 mg/d.
These groups were then randomly put into
subgroups that received either 500 mg Ca/d or placebo.
Measurements of whole body bone mineral content,
bone area, bone mineral density, and bone mineral content
adjusted for bone area, height, and weight were
performed at baseline and after one year of the
supplementation. The level of habitual dietary calcium
intake had no effect on the impact of calcium
supplementation for the parameters measured. Calcium
supplementation had a modest beneficial effect on bone
mineral density, which was independent of the
habitual calcium intake.
THE LINK
BETWEEN SELENIUM AND CHEMOPREVENTION: A CASE FOR
SELEOPROTEINS.
Veda Diwadkar-Navsariwala and Alan M. Diamond.
J Nutr 134:2899-2902, 2004.
Animal models, epidemiological data and human
supplementation trials have indicated that selenium is
likely to be an effective nutrient in the reduction of
cancer incidence. Its mechanism is not yet known. The
mammalian genome encodes 25 selenoprotein genes, each
containing one or more molecules of selenium in
the form of a selenocysteine, translationally inserted into
the growing peptide in response to the UGA codon
which signals the termination of protein synthesis. There is
evidence that several of these proteins may be
involved with the mechanism by which selenium provides its
anti-cancer effects. Data is reviewed relative
to genetic variances of cytosolic glutathione peroxidase and
cancer risk. These date, along with differential
expression patterns reported for other selenoproteins in
tumor versus normal tissues offer support for the
role of selenoproteins in chemoprotection by selenium.
CALCIUM
INTAKE AND COLORECTAL ADENOMA IN A US COLORECTAL CANCER
EARLY
DETECTION PROGRAM.
Peters U, et al.
Am J Clin Nutr 2004:80:1358-1365.
Calcium can bind secondary bile and fatty acids, which has
antiproliferatrive effects on the bowel, and it
acts directly on the colonic epithelium, impacting
differentiation and apoptosis. This is believed to reduce
the risk of colorectal tumors. This study attempts to
evaluate the association of calcium intake with early
stages of colorectal tumor development. In this study, the
dietary calcium intake of 3,696 patients with
histologically verified adenoma of the distal colon with the
calcium intakes of 34,817 sigmoidoscopynegative
control participants in the Prostate, Lung, Colorectal, and
Ovarian Cancer Screening Trial.
Assessment of calcium intake was done at the study entry via
a 137 item food frequency questionnaire plus
additional questions on calcium supplement use. The risk of
adenoma was found to be 12% lower for those
of the highest quintile in calcium intake. The protective
benefit for total calcium versus colorectal adenoma
was largely due to calcium supplement use. The usage of
>1200mg/d of calcium supplementation yielded a
27% decrease in adenoma risk compared to non-supplement
users. High calcium intake, particularly from
supplements is associated with a reduced risk of distal
colorectal adenoma.END
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