Selenium: Under-Appreciated and Underestimated

Minerals are necessary for proper function of the body's systems. Macro-minerals such as calcium are required in large amounts. Trace minerals like selenium, iron, and zinc are required in very small amounts. Selenium plays an important part in enzyme functions, and it is also considered to be an antioxidant. It is an aid in the production of interferon, which stops the reproduction of viruses. Selenium works with vitamin C and vitamin E (other antioxidants) to control free radicals. It is believed to work as a stimulant for antibody production after a vaccination. It also plays a vital role in maintaining healthy cell membranes. In another important role, selenium aids in the production of joint lubricant to keep your joints working smoothly. This can delay or prevent the onset of rheumatoid arthritis.

Selenium has the ability to bond with heavy metals that may be in your body. These can be from different sources such as breathing polluted air, smoking, or from ingestion (mercury from fish). The bonding process makes it possible for the hazardous molecules to be excreted. A similar bonding process occurs with the iron that remains in dead red blood cells. Selenium helps "recycle" these iron molecules by aiding in a process in which the iron from the dead cell bonds to a protein, making it too large for the kidneys to filter out. In essence, this returns the iron to the body for reuse.

Selenium occurs naturally in the soil and water, where it is absorbed by plants we eat. If we were to ingest selenium in the form in which it occurs in the soil, it would actually be poisonous. Plants alter it into a form our bodies can use. Selenium is found in higher concentrations in volcanic soil. The higher the soil concentration of selenium, the more the foods grown in that soil will contain. There can be as much of a difference as 200 times the amount of selenium in foods grown in different regions of the country. This is true of our direct consumption of fruits and vegetables grown on selenium-rich soil, and also indirect foods such as meat, milk, and eggs produced by animals that were raised on feed grown in selenium-rich soil.

Deficiency is very uncommon, though. Plenty of selenium is found naturally in most of our fresh food supply. However, it is destroyed if foods are processed. Fresh foods that contain a relative abundance of selenium are Brazil nuts, salmon, scallops and oysters, whole grains, sunflower seeds, molasses, organ meats, ground beef, and chicken breast. Eggs, milk, and cheese have small amounts of selenium. It is also included in most multi-vitamin tablets, so if you eat balanced meals with fresh fruits and vegetables and take your vitamins, you are getting an adequate supply of this trace mineral.

According to WebMD, 55 mcg per day is recommended adult dose of selenium. The safe upper limit has been set at 400 mcg per day, but symptoms of overdose can occur at much lower levels. Overdosing can have severe side effects, so this supplement is one you probably don't need to take unless recommended by your health care practitioner.

http://www.feinberg.northwestern.edu/nutrition/factsheets/selenium.html
http://www.lifeclinic.com/focus/nutrition/selenium.asp
http://ods.od.nih.gov/factsheets/selenium.asp