SELENIUM
LOW SELENIUM STATUS AND THYROID STIMULATION
Selenium is essential for the production and regulation
of thyroid hormones. A study was designed to investigate
thyroid function across large variations in dietary selenium
intakes and correlate this with blood levels of selenium
and thyroid health. 68 healthy men, previously screened
for endocrine disease, selenium supplements and food frequency
data, gave blood for analysis of plasma selenium and thyroid
hormones.
Results revealed that plasma selenium was positively and
significantly correlated with the number of fish meals per
month. Thyroid-stimulating hormone (TSH) was negatively
and significantly correlated with plasma selenium levels.
This suggests that low selenium status causes a homoeostatic
increase in TSH.
Hagmae, L. et al,
EUR. J. CLIN. NUTR. 1998, 52, 796-800
Courtesy Lamberts Nutrition Bites
IMPACT OF TRACE ELEMENTS AND VITAMIN SUPPLEMENTATION ON
IMMUNITY AND INFECTIONS IN INSTITUTIONALISED ELDERLY PATIENTS
It is well known that ageing is often associated with a
poor immune response, particularly the cell-mediated response,
and substantial vulnerability to respiratory tract infections.
Nutritional status has been recognised as a strong factor
in immune impairment, especially in elderly persons in institutions,
but there have been few large trials in elderly people that
have included end points for clinical variables.
Therefore, a study was carried out to determine the effects
of long-term daily supplementation with trace elements (zinc
sulphate and selenium sulfide) or vitamins (beta-carotene,
ascorbic acid, and vitamin E) on immunity and the incidence
of infections in institutionalised elderly people. Patients
received an oral daily supplement of nutritional doses of
trace elements or vitamins or a placebo for 2 years. Correction
of specific nutrient deficiencies was observed after 6 months
of supplementation and was maintained for the first year.
The number of patients without respiratory tract infections
during the study was higher in groups that received trace
elements.
Thus, low-dose supplementation of zinc and selenium provides
significant improvement in elderly patients by increasing
the humoral response after vaccination and could have considerable
public health importance by reducing morbidity from respiratory
tract infections.
Girodon, F. et al
ARCH.INTERN.MED. 1999, 159 (7) 748-54
SELENIUM AND RISK OF PROSTATE CANCER
Selenium, an essential trace nutrient found largely in
grains, fish, and meats, enters the food chain through plants
at geographically variable rates dependent on selenium concentrations
in the soil. For this reason selenium intake varies substantially
across populations. The recommended daily allowance for
selenium in men is 70ug in the USA and 75ug in the UK.
A US study has revealed an inverse association between
advanced prostate cancer and toenail selenium concentrations.
The multivariate-adjusted relative risk comparing the highest
with the lowest quintile of toenail selenium was 0.35. With
daily median selenium intake estimated on the basis of toenail
concentration, intake was 86 ug among men in the lowest
quintile and 159 ug among those in the highest quintile.
The evidence now available indicates that substantial increases
in consumption of selenium by men taking 80-90 ug a day
or more may have a striking impact on prostate cancer rates.
In the UK, selenium intakes have been falling over several
decades largely because of a decrease in imported flour
from North America in favour of selenium-poor flour of European
countries. Recent surveys indicate that the average intake
of selenium may be as low as 30-40ug/day.
Giovannucci, E.
LANCET 1998, 352 (9130) 755-6
PROTECTIVE ROLE OF SELENIUM
Studies in China have found that selenium supplementation
has a protective effect against hepatitis B virus and primary
liver cancer, and that a continuous intake is essential
to sustain the chemopreventive effect.
Yu S.Y. et al,
BIOL. TRACE ELEM. RES. 1997, 117-24
Courtesy POSITIVE HEALTH, March 1998
FALL IN UK SELENIUM - RESEARCH NEEDED
Recent studies show that we may be getting as little as
half the current recommended levels of selenium from our
diets. Selenium is a trace mineral found in bread and cereals,
fish, poultry and meat. It has been suggested that it may
protect us against some cancers, fertility problems, and
heart disease. One of the reasons why there may be less
of it in our diets than 20 years ago may be because the
European wheat now widely used in breadmaking in the UK
is selenium-poor, but also because we are eating less cereal
overall. A daily handful of brazil nuts, the richest source
of the mineral, should give you enough to meet current recommended
levels.
HEALTH WHICH 1998, 7th April
