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What Is It
A trace mineral essential for many body processes, selenium
is found in soil. In the body, selenium is present in virtually
every cell but is most abundant in the kidneys, liver, spleen,
pancreas, and testes.
What Does It Do
Selenium acts as an antioxidant, blocking the rogue molecules
known as free radicals that damage DNA. It's part of an antioxidant
enzyme (called glutathione peroxidase) that protects cells
against environmental and dietary toxins, and is often included
in antioxidant "cocktails" with vitamins C and E.
This combination may help guard against a range of disorders,
from cancer, heart disease, cataracts, and macular degeneration
to strokes and even aging, thought to be caused by free-radical
damage.
Common Uses
• Works with vitamin E to help prevent cancer and heart
disease.
• Protects against cataracts and macular degeneration.
• Fights viral infections; reduces the severity of cold
sores and shingles; may slow the progression of HIV/AIDS.
• Helps relieve lupus symptoms.
Major Benefits
Selenium has received a lot of attention recently for its
role in combating cancer. A dramatic five-year study conducted
at Cornell University and the University of Arizona showed
that 200 mcg of selenium daily resulted in 63% fewer prostate
tumors, 58% fewer colorectal cancers, 46% fewer lung malignancies,
and a 39% overall decrease in cancer deaths. In other studies,
selenium showed promise in preventing cancers of the ovaries,
cervix, rectum, bladder, esophagus, pancreas, and liver, as
well as against leukemia. Studies of cancer patients indicate
that people with the lowest selenium levels developed more
tumors, had a higher rate of disease recurrence, a greater
risk of cancer spreading, and a shorter overall survival rate
that those with high blood levels of selenium.
Additionally, selenium can protect the heart, primarily by
reducing the "stickiness" of the blood and decreasing
the risk of clotting - in turn, lowering the risk of heart
attack and stroke. Moreover, selenium increases the ratio
of HDL ("good") cholesterol to LDL ("bad")
cholesterol, which is critical for a healthy heart. Smokers
or those who've already had a heart attack or stroke may gain
the greatest cardiovascular benefits from selenium supplements,
though everyone can profit from taking selenium in a daily
vitamin and mineral supplement.
Additional Benefits
Selenium may be useful in preventing cataracts and macular
degeneration, the leading causes of impaired vision or blindness
in older Americans. It is also vital for converting thyroid
hormone, which is needed for the proper functioning of every
cell in the body, from a less active form (called T4) to its
active form (known as T3). In addition, selenium is essential
for a healthy immune system, assisting the body in defending
itself against harmful bacteria and viruses, as well as cancer
cells. Its immune-boosting effects may play a role in fighting
the herpes virus that is responsible for cold sores and shingles,
and it is also being studied for possible effectiveness against
HIV, the virus that causes AIDS.
When combined with vitamin E, selenium appears to have some
anti-inflammatory benefits as well. These two nutrients may
improve chronic conditions such as rheumatoid arthritis, psoriasis,
lupus, and eczema.
How Much You Need
The RDA for selenium is 70 mcg for men, and 55 mcg for women
daily. To produce major benefits, up to 600 mcg a day may
be needed.
If You Get Too Little: Most Americans consume
enough selenium in their daily diet, so deficiencies are rare.
Falling below the RDA, however, may lead to higher incidences
of cancer, heart disease, immune problems, and inflammatory
conditions of all kinds, particularly those affecting the
skin. Insufficient amounts of selenium during pregnancy could
increase the risk of birth defects (especially those involving
the heart) or, possibly, sudden infant death syndrome (SIDS).
Early symptoms of selenium deficiency include muscular weakness
and fatigue.
If You Get Too Much: It's hard to get to
much selenium from your diet, but if you're taking this mineral
in supplement form, it's important to remember that the margin
of safety between a therapeutic dose of selenium (up to 600
mcg a day) and a toxic dose (as little as 900 mcg) is small
compared with other nutrients. Symptoms of toxicity include
nervousness, depression, nausea and vomiting, a garlicky odor
to the breath and perspiration, and a loss of hair and fingernails.
How To Take It
Dosage: Most experts agree the optimum dose for long-teerm
use of selenium should fall between 100 mcg and 400 mcg daily.
Up to 600 mcg daily may be taken for a limited time as a treatment
for viral infections or as part of a cancer treatment program.
Guidelines For Use: Vitamin E greatly enhances
selenium's effectiveness; be sure that you get 400 IU of it
daily.
Other Sources
The most abundant sources of selenium include Brazil nuts,
seafood, poultry, and meats. Grains, particularly oats and
brown rice, may also have significant amounts, depending on
the selenium content of the soil in which they were grown.
Caution!
Don't exceed recommended doses: In some people, taking selenium
long term (as little as 900 mcg a day) can cause serious side
effects, such as skin rashes, nausea, fatigue, hair loss,
fingernail changes, and depression.
Latest Findings
• Recent studies show that in the test tube selenium
works relatively quickly, helping cells grow and die at normal
rates and protecting them from becoming cancerous. Experts
suspect that selenium's cancer-fighting benefits may be fairly
fast-acting in the body as well.
• According to the journal Agriculture Research, studies
in mice show that a deficiency in either selenium or vitamin
E both antioxidants - can convert a latent, inactive virus
into its active, disease-causing form. This may help explain
why selenium is effective against cold sores and shingles,
which are both caused by reactivation of a dormant herpes
virus.
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