Selenium
Why do I need selenium?
Humans are made from earth, within the soils of the earth are some important nutrients. Selenium is an essential trace element for humans and other animals. Essental trace element is a substance that is required by the body in very small amounts for proper growth and functioning. Usually obtained from the diet, small amounts of selenium are known to be necessary for several human biologic processes, including immune response and thyroid function. Selenium is incorporated into molecules of an enzyme called glutathione peroxidase (GPX). This vital enzyme protects red blood cells and cell membranes against undesirable reactions with soluble peroxides. Good selenium nutrition is of key importance for antioxidant defense as well as efficient energy metabolism.
Selenium is required for the activation
of an enzyme called glutathione
peroxidase. This enzyme is an
antioxidant that quenches hydroperoxides,
"high energy" oxygen-containing
molecules that are produced during the
metabolism of fat and that are highly
toxic to cells. Recent research showed
that selenium could reduce the severity
of some cancers. This is thought to be
due to selenium inducing "apoptosis"
(programmed cell death) in cancer cells.
Selenium is also involved in a healthy
immune system and proper thyroid
function.
Where is selenium found?
- Brazil nuts
- Yeast
- Whole grains
- Seafood
Do I need selenium?
Deficiency is rare in Western countries. Soils in some areas are selenium deficient, and people who eat foods grown primarily in those soils are at risk for deficiency. However, in today's supermarket, foods come from far and wide, thus compensating for poor local soil conditions.
What causes Selenium deficiency?
Chronic alcohol use depletes selenium stores in the
body. widespread infections can also
lead to decreases in selenium.
Individuals with long-term
gastrointestinal illnesses, such as
Crohn's disease, may not absorb enough
selenium from foods
What diseases show Selenium deficiency?
Abnormally low levels of selenium in the body may also be associated with a number medical conditions, including anxiety disorders, asthma, depression, heart disease, rheumatoid arthritis, and seizures.
What research is currently being conducted on the protective effects of Se in humans against :
- Aging
- Cancer: prostate, lung, and colorectal cancers. No effectiveness for preventing or controlling breast cancer, leukemia, lymphoma, and melanoma. In one large human study, selenium supplementation was actually associated with an increased risk of developing certain skin cancers.
- Heart disease
- Cataract
- Arthritis
- Alzheimer disease
- HIV infection
- Anemia
Caution
Concomitant use of ascorbic acid (vitamin C) may inactivate sodium selenite supplements.
Recommended daily dose
50-200 mg /day. Most individuals who eat a "western-style" diet get enough selenium from meats or seafood, whole grains, and vegetables grown in selenium-rich soil.
What do animal studies show ?
In animal studies, supplemental selenium has been associated with recovery of at least partial muscle control after spinal cord injury or brain damage. Animal studies have also shown a possible decrease in blood glucose among diabetic animals given selenium. It may also help to control some of the complications (damage to the eyes, kidneys, and nerves) caused by diabetes. Oversupply of selenium is associated with development of insulin resistance and diabetese.
What to look for in a selenium supplement
Selenomethionine is the principal form of selenium found in foods. Selenomethionine is virtually 100% absorbed and well retained as compared to inorganic selenium, which is rapidly excreted.
Yeast preparations can be produced to contain substantial amounts of selenomethionine suitable for selenium supplements.
Some manufacturers mechanically mix
sodium selenite or selenium dioxide,
with ordinary yeasts. These yeast
products contain virtually no
selenomethionine. The selenium in
these yeasts is significantly less
bioavailable than selenomethionine.
Studies have shown that such yeast
products produce only small
increases in blood selenium
concentrations.
Other artificially selenized yeasts
contain sodium selenate, which is
not normally present in foods. A
study found that selenate was less
effective than selenomethionine to
correct a deficiency.
Read labels to determine which form
of selenium is in the supplement.
Best choice: selenomethionine.
