Selenium
One thing I have often written about in this column is the damage done in the
body by free radicals. This month I want to talk about selenium, a mineral that
serves as a protective agent for cells against destruction by free radicals.
Selenium works in a supporting role with an enzyme called glutathione
peroxidase. You can think of these two as the Batman and Robin of free radical
mayhem.
Every day, an abundance of free radicals are created in our bodies as a result
of exposure to environmental insults such as smog, chemicals, drugs, radiation,
and as a byproduct of normal physiological processes. Once formed, free
radicals “attack” by taking electrons away from the DNA, proteins, and fatty
acids within our cells. Damage to these cellular components has been implicated
as the cause of dozens of diseases including atheroscelorsis, cancer, premature
aging, and many others. The primary mechanism by which the body gets rid of
free radicals is by converting them to other compounds with the help of
antioxidant nutrients such as vitamins C, and E, and enzymes such as
glutathione peroxidase. This enzyme is found in cells throughout the body and
has a crucial role in this fight, but it requires the presence of the mineral
selenium to carry out its duties.
Interestingly, the concentration of selenium in soil varies greatly throughout
the world. This results in a variable concentration in the food depending on
the soil in which it was grown. This uneven distribution makes it easy to see
the correlation between selenium poor diets and the diseases associated with
selenium deficiency. Tissues containing high amounts of selenium include the
heart, muscle, kidney, and bone. Not surprisingly, severe selenium deficiency
leads to diseases such as congestive heart failure and degeneration of the
joints. Less severe deficiencies of selenium have been connected to
cardiovascular disease, cancer, muscle pain, weakness, and impaired function of
the immune system.
Excellent sources of selenium include cold water fish, shellfish, and Brazil
nuts (just one nut a day will fulfill daily requirements). Very good sources
include sunflower seeds, barley, oats and chicken eggs.
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