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Challenges and opportunities in the translation of the science of
vitamins.
Am J Clin Nutr. 2007 Jan;85(1):325S-7S.
Some 100 y after
the description and naming of the first vitamin, this conference on
the state-of-the-science has shown that remarkable and exciting
advances have been made in our understanding of the biology,
chemistry, and metabolism of vitamins, explaining their essentiality
in the diet. A great deal more needs to be done in the translation of
this knowledge into an understanding of the benefit of vitamin
supplements to disease prevention and to health and well-being. Not
only are advances in fundamental science and biology necessary, but
more attention must be paid to genomics, epigenetics, behavioral
science, and new techniques for evidence analysis of studies.
Information relating individual vitamins or small combinations of
vitamins to disease prevention is stronger than that for
multivitamins, formulations that cry out for greater standardization.
This large task of translating emerging science to better policy in
the field of vitamin and multivitamin-mineral supplement use should
occupy our attention intensively in the years to come. Issues needing
more attention include the content and labeling of such products and
the effects of the products on nutrient adequacy as well as in chronic
degenerative disease prevention. In this quest, the development of
more and better surrogate markers will be critical. Dose-response
assessments of safety are badly needed for updating Tolerable Upper
Intake Levels. At its best, all of these disparate types of research
will require a robust interaction between the public and private
sectors in a regulatory framework that supports and rewards investment
in good science.
Multivitamin
supplementation improves hematologic status in HIV-infected women and
their children in Tanzania.Am
J Clin Nutr. 2007 May;85(5):1335-43.
BACKGROUND:
Anemia is a frequent complication among HIV-infected persons and is
associated with faster disease progression and mortality. OBJECTIVE:
We examined the effect of multivitamin supplementation on hemoglobin
concentrations and the risk of anemia among HIV-infected pregnant
women and their children. DESIGN: HIV-1-infected pregnant women (n =
1078) from Dar es Salaam, Tanzania, were enrolled in a double-blind
trial and provided daily supplements of preformed vitamin A and
beta-carotene, multivitamins (vitamins B, C, and E), preformed vitamin
A and beta-carotene + multivitamins, or placebo. All women received
iron and folate supplements only during pregnancy according to local
standard of care. The median follow-up time for hemoglobin measurement
for mothers was 57.3 mo [interquartile range (IQR): 28.6-66.8] and for
children it was 28.0 mo (IQR: 5.3-41.7). RESULTS: During the whole
period, hemoglobin concentrations among women who received
multivitamins were 0.33 g/dL higher than among women who did not
receive multivitamins (P=0.07). Compared with placebo, multivitamin
supplementation resulted in a hemoglobin increase of 0.59 g/dL during
the first 2 y after enrollment (P=0.0002). Compared with placebo, the
children born to mothers who received multivitamins had a reduced risk
of anemia. In this group, the risk of macrocytic anemia was 63% lower
than in the placebo group (relative risk: 0.37: 95% CI: 0.18, 0.79;
P=0.01). CONCLUSION: Multivitamin supplementation provided during
pregnancy and in the postpartum period resulted in significant
improvements in hematologic status among HIV-infected women and their
children, which provides further support for the value of multivitamin
supplementation in HIV-infected adults.
NIH
State-of-the-Science Conference Statement on Multivitamin/Mineral
Supplements and Chronic Disease Prevention.NIH
Consens State Sci Statements. 2006 May
15-17;23(2):1-30.
OBJECTIVE: To
provide health care providers, patients, and the general public with a
responsible assessment of currently available data on
Multivitamin/Mineral Supplements and Chronic Disease Prevention.
PARTICIPANTS: A non-DHHS, non-advocate 13-member panel included
experts in the fields of food science and human nutrition,
biostatistics, biochemistry, toxicology, geriatric medicine, family
medicine, pediatrics and pediatric endocrinology, cancer prevention,
epidemiology, disease prevention and health promotion, and consumer
protection. In addition, 19 experts from pertinent fields presented
data to the panel and conference audience. EVIDENCE: Presentations by
experts and a systematic review of the literature prepared by The
Johns Hopkins University Evidence-based Practice Center, through the
Agency for Healthcare Research and Quality. Scientific evidence was
given precedence over anecdotal experience. CONFERENCE PROCESS: The
panel drafted its statement based on scientific evidence presented in
open forum and on published scientific literature. The draft statement
was presented on the final day of the conference and circulated to the
audience for comment. The panel released a revised statement later
that day at http://consensus.nih.gov. This statement is an independent
report of the panel and is not a policy statement of the NIH or the
Federal Government. CONCLUSIONS: Use of multivitamins/minerals (MVMs)
has grown rapidly over the past several decades, and dietary
supplements are now used by more than half of the adult population in
the United States. In general, MVMs are used by individuals who
practice healthier lifestyles, thus making observational studies of
the overall relationship between MVM use and general health outcomes
difficult to interpret. Despite the widespread use of MVMs, we still
have insufficient knowledge about the actual amount of total nutrients
that Americans consume from diet and supplements. This is at least in
part due to the fortification of foods with these nutrients, which
adds to the effects of MVMs or single-vitamin or single-mineral
supplements. Historically, fortification of foods has led to the
remediation of vitamin and mineral deficits, but the cumulative
effects of supplementation and fortification have also raised safety
concerns about exceeding upper levels. Thus, there is a national need
to improve the methods of obtaining accurate and current data on the
public's total intake of these nutrients in foods and dietary
supplements. In systematically evaluating the effectiveness and safety
of MVMs in relation to chronic disease prevention, we found few
rigorous studies on which to base clear conclusions and
recommendations. Most of the studies we examined do not provide strong
evidence for beneficial health-related effects of supplements taken
singly, in pairs, or in combinations of three or more. Within some
studies or subgroups of the study populations, there is encouraging
evidence of health benefits, such as increased bone mineral density
and decreased fractures in postmenopausal women who use calcium and
vitamin D supplements. However, several other studies also provide
disturbing evidence of risk, such as increased lung cancer risk with
beta-carotene use among smokers. The current level of public assurance
of the safety and quality of MVMs is inadequate, given the fact that
manufacturers of these products are not required to report adverse
events and the FDA has no regulatory authority to require labeling
changes or to help inform the public of these issues and concerns. It
is important that the FDA's purview over these products be authorized
and implemented. Finally, the present evidence is insufficient to
recommend either for or against the use of MVMs by the American public
to prevent chronic disease. The resolution of this important issue
will require advances in research and improved communication and
collaboration among scientists, health care providers, patients, the
pharmaceutical and supplement industries, and the public.
Micronutrients
in women's reproductive health: I. Vitamins.Int
J Fertil Womens Med. 2006
May-Jun;51(3):106-15.
Proper
nutritional status of women before, during, and after pregnancy is an
important element of reproductive health. It maintains maternal health
and reduces the risk of adverse pregnancy outcome, birth defects and
chronic disease in children later in postnatal life. Pregnancy creates
a special metabolic demand for high-quality nutrients. With careful
food selection, it is possible to obtain most of the recommended
levels of nutrients. Apart from the dietary intake, nutrition is
highly dependant on economic status, social and cultural environment,
and personal habits of the mother. Nutritional imbalance could cause
detrimental effects to the pregnant woman, influence pregnancy
outcome, and impair breast milk composition. Despite the extensive
research, we still do not have a complete understanding how
nutritional status of the mother influences her health as well as
fetal growth and development. It is well known that fetal growth and
development is strongly linked with maternal supply of essential
nutrients, e.g. vitamins. The exact role of the variety of
micronutrients in fetal growth and development has yet to be explored
in detail. It is estimated that up to 30% of pregnant women suffer
from a vitamin deficiency. Without supplementation, about 75% would
show a deficit of at least one vitamin. Moreover, multivitamin deficit
combinations often co-exist, and subclinical depletations are probably
common; consequences could be severe. Studies carried on in developing
countries have shown that improving micronutrient intake in deficient
women can reduce maternal morbidity and mortality. Also, proper
maternal intake of important micronutrients directly enhances the
quality of breast milk. To meet the increasing demands during
pregnancy and the breastfeeding period women should not be dependent
only upon the dietary intake: adequate reserve is essential for the
successful pregnancy outcome.
Vitamins and
trace elements: Practical aspects of supplementation.Nutrition.
2006 Sep;22(9):952-5.
The role of
micronutrients in parenteral nutrition include the following: (1)
Whenever artificial nutrition is indicated, micronutrients, i.e.,
vitamins and trace elements, should be given from the first day of
artificial nutritional support. (2) Testing blood levels of vitamins
and trace elements in acutely ill patients is of very limited value.
By using sensible clinical judgment, it is possible to manage patients
with only a small amount of laboratory testing. (3) Patients with
major burns or major trauma and those with acute renal failure who are
on continuous renal replacement therapy or dialysis quickly develop
acute deficits in some micronutrients, and immediate supplementation
is essential. (4) Other groups at risk are cancer patients, but also
pregnant women with hyperemesis and people with anorexia nervosa or
other malnutrition or malabsorption states. (5) Clinicians need to
treat severe deficits before they become clinical deficiencies. If a
patient develops a micronutrient deficiency state while in care, then
there has been a severe failure of care. (6) In the early acute phase
of recovery from critical illness, where artificial nutrition is
generally not indicated, there may still be a need to deliver
micronutrients to specific categories of very sick patients. (7)
Ideally, trace element preparations should provide a low-manganese
product for all and a manganese-free product for certain patients with
liver disease. (8) High losses through excretion should be minimized
by infusing micronutrients slowly, over as long a period as possible.
To avoid interactions, it would be ideal to infuse trace elements and
vitamins separately: the trace elements over an initial 12-h period
and the vitamins over the next 12-h period. (9) Multivitamin and trace
element preparations suitable for most patients requiring parenteral
nutrition are widely available, but individual patients may require
additional supplements or smaller amounts of certain micronutrients,
depending on their clinical condition.
Studies of
vitamins and minerals and HIV transmission and disease progression.J
Nutr. 2005 Apr;135(4):938-44.
HIV-1
infection is having a devastating impact on people in developing
countries. Poor nutrition and HIV-related adverse health outcomes
contribute to a vicious cycle that may be slowed down by using
nutritional interventions, including vitamins and minerals. Among
children, periodic supplementation with vitamin A starting at 6 mo of
age has been shown to be beneficial in reducing mortality and
morbidity among both HIV-infected and uninfected children. Limited
data exist on the role of other nutrient supplements among children.
Among HIV-infected adults, the safety and the efficacy of vitamin A
supplements need further study, although adequate dietary intake of
this essential nutrient is recommended. Multivitamin supplements were
efficacious in reducing adverse pregnancy outcomes and early childhood
infections, and is currently provided to pregnant HIV-infected
pregnant women in many programs. The efficacy of such supplements
among HIV-negative pregnant women needs further study. Daily
multivitamin supplements were found to reduce HIV disease progression
among men and women in several observational studies and randomized
trials, and to provide an important low-cost intervention that could
be provided to adults in early stages of HIV disease to prolong the
time before antiretroviral therapy is recommended. Next, research
priorities include examining the roles of minerals, including
selenium, in HIV infection, as well as determining the safety and the
efficacy of micronutrient supplements among individuals who are
advanced in their disease and who are receiving antiretroviral
therapy.
Design of
Physicians' Health Study II--a randomized trial of beta-carotene,
vitamins E and C, and multivitamins, in prevention of cancer,
cardiovascular disease, and eye disease, and review of results of
completed trials.Ann
Epidemiol. 2000 Feb;10(2):125-34.
PURPOSE: To
assess the balance of benefits and risks of supplementation with
beta-carotene, vitamin E, vitamin C, and multivitamins on cancer,
cardiovascular (CVD), and eye diseases. DESIGN: Physicians' Health
Study II (PHS II) is a randomized, double-blind, placebo-controlled
trial enrolling 15,000 willing and eligible physicians aged 55 years
and older. PHS II will utilize a 2 x 2 x 2 x 2 factorial design to
test alternate day beta-carotene, alternate day vitamin E, daily
vitamin C, and a daily multivitamin, in the prevention of total and
prostate cancer, CVD, and the age-related eye diseases, cataract and
macular degeneration. PRIOR RESULTS: The final results of the recently
completed Physicians' Health Study I (PHS I), a randomized,
double-blind, placebo-controlled trial in 22,071 healthy US male
physicians, indicated that beta-carotene supplementation (50 mg on
alternate days) had no significant benefit or harm on cancer or CVD
during more than 12 years of treatment and follow-up. In regards to
cancer, there were possible benefits on total and prostate cancer in
those with low baseline levels assigned to beta-carotene, a finding
compatible with the Chinese Cancer Prevention Study for combined
treatment with beta-carotene, vitamin E, and selenium in a poorly
nourished population. Further, with respect to CVD, there were
apparent benefits of beta-carotene supplementation on subsequent
vascular events among a small subgroup of 333 men with prior angina or
revascularization. The currently available data from randomized trials
of primary prevention are sparse and inconsistent for vitamin E and
non-existent for vitamin C and multivitamins. For eye diseases, namely
cataract and age-related macular degeneration, there are no completed
large-scale randomized trials of antioxidant vitamins. CONCLUSIONS:
PHS II is unique in several respects. PHS II is the only primary
prevention trial in apparently healthy men testing the balance of
benefits and risks of vitamin E on cancer and CVD. In addition, PHS II
is the only primary prevention trial in apparently healthy men to test
the balance of benefits and risks of vitamin C, multivitamins, as well
as any single antioxidant vitamin, alone and in combination, on
cancer, CVD, and eye diseases. Finally, PHS II is the only trial
testing a priori the hypotheses that beta-carotene and vitamin E may
reduce the risks of prostate cancer. Thus, PHS II will add unique as
well as importantly relevant and complementary information to the
totality of evidence from other completed and ongoing large-scale
randomized trials on the balance of benefits and risks of
beta-carotene, vitamin E, vitamin C, and multivitamins alone and in
combination on prevention of cancer, CVD and eye diseases.
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