August 14, 2012

Nutrients – Selenium


Selenium deficiency for those of us living in the United States is generally rare. I suggest reading my blog on selenium linked here. Excess selenium can indeed cause more harm than good so please be careful with selenium. Use this US map for determining if the food you eat comes from an area that is selenium deficient.

Selenium is an essential trace mineral found in small amounts in our body. Selenium plays a part in thyroid function and our immune system needs selenium to work properly. There are many other areas where selenium is maybe playing a role, but scientists have not determined the cause-effect in these areas. Even another area that needs more investigation is the finding that people that used selenium supplements of less than 200 mcg per day for more than seven years were at a significantly higher risk for developing type 2 diabetes.

Because of this and the number of medications that may be conflicting with selenium, it is strongly urged that people only take selenium supplements under the supervision of a doctor knowledgeable in selenium.

Potential for Deficiency
If you are healthy and eat a well-balanced diet, you should get enough selenium. You may have low levels of selenium if you:
  • Smoke cigarettes
  • Drink alcohol
  • Take birth control pills
  • Have a condition that prevents your body from absorbing enough selenium such as Crohn's disease or ulcerative colitis

Trace mineral testing is usually performed on a blood sample. Sometimes a 24-hour urine collection is obtained. Special metal-free blood or acid-washed urine containers are used to minimize the potential for sample contamination by any outside sources of minerals.

Blood and urine reflect recent mineral intake. Rarely, hair may be collected or a biopsy may be performed to obtain a tissue sample to evaluate mineral deficiencies, excesses, and storage that have occurred over time.

Recommended Daily Allowance
The minimum daily recommended dietary allowances (RDA) for selenium are listed below.
Children 1 - 3 years: 20 mcg
Children 4 - 8 years: 30 mcg
Children 9 - 13: 40 mcg
Children 14 - 18: 55 mcg
19 and older: 55 mcg
Pregnant women: 60 mcg
Breastfeeding women: 70 mcg
As a supplement: Some studies have used 200 mcg per day for some conditions, but evidence suggests that taking that amount over a long time could increase your risk of developing diabetes. Talk to your doctor before taking more than the recommended daily allowance.

Food Sources
Dietary sources include the following: brewer's yeast and wheat germ, liver, butter, fish (mackerel, tuna, halibut, flounder, herring, smelts) and shellfish (oysters, scallops, and lobster), garlic, whole grains, sunflower seeds, and Brazil nuts are all good sources of selenium.

Selenium levels in food depend on where the food was grown. Selenium is destroyed when foods are refined or processed. Eating a variety of whole, unprocessed foods is the best way to get selenium in your diet.

Available Forms:
Selenium may be taken as part of a vitamin-mineral supplement, a nutritional antioxidant formula, or as a separate supplement. Most supplements contain a form of selenium called selenomethionine.

There is a health risk of too much selenium. This happens when high blood levels become greater than 100 mcg/dl (micrograms per deciliter). This may result in a condition called selenosis. Selenosis symptoms include hair loss, white blotchy nails, gastrointestinal upset, garlic breath, fatigue, irritability, and mild nerve damage. In the USA, selenium toxicity is rare.

The Institute of Medicine of the National Academy of Sciences has set a tolerable upper intake level (UL) for selenium. Tolerable upper intake levels for selenium for infants, children, and adults to prevent selenosis is provided in the following table:
Males and Females
0–6 months
7–12 months
1–3 years
4–8 years
9–13 years
14–18 years
19+ years

Possible Interactions
There are many interactions that are known for selenium and some will lessen the effectiveness of the medications. Therefore, it is important that if you are having any of the following that you discuss this with a doctor knowledgeable about selenium. The list of medication conflicts is extensive and I urge you to read this. The areas that you need to be aware of include – cancer, chemotherapy, cholesterol-lowering medications, birth control pills, and gold salts.

Please read this if you have arthritis. Selenium does work with and supports iodine in the thyroid function.

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