Selenium (Se) is a trace mineral that can be found in foods and supplements.[1] It is available in both organic and inorganic forms and is an essential nutrient for humans and animals.[2] In the body, selenium works as an antioxidant http://www.dreddyclinic.com/forum/viewtopic.php?f=21&t=32801, protecting cells from free radical damage. It has an important role in thyroid hormone synthesis, the male reproductive system, and other bodily processes.[3, 4]
How Is Selenium Found in Our Diet?
The amount of selenium in plants is directly linked to the concentration of the element in the soil.[5] Plants absorb inorganic selenium from the earth and convert it into organic forms.[6] Environmental factors affect the amount of selenium a plant absorbs. The pH of the soil, temperature, air humidity, and ground moisture all affect selenium uptake.[7] Because of these variations, selenium concentration in plant-based foods http://www.dreddyclinic.com/forum/viewtopic.php?f=21&t=33532 varies region to region. Selenium levels can change over such a small area that the vegetables in your neighbor’s garden may have more selenium than yours.[8]
Selenium content in meat can also vary, although not as drastically. The selenium content of animal products depends on the concentration of the element in the plants they eat.[1] What does this variation mean for our daily selenium requirements?
Recommended Intake
When you look at a nutrition label you’ll see the Recommended Dietary Allowance (RDA). The RDA is defined as the “average daily level of intake sufficient to meet the nutrient requirements of nearly all (97%–98%) healthy people.”[1] Notice the definition says “sufficient” and not “optimal.” Every person’s needs differ. A breastfeeding woman needs much more selenium than a nine-year-old boy, for example. Your optimal selenium requirements may be higher or lower than what the label says. The following chart provides a more complete perspective about daily selenium requirements.
Life Stage Selenium Requirement (in micrograms)
Birth – 6 months 15 mcg
7-12 months 20 mcg
1-3 years 20 mcg
4 – 8 years 30 mcg
9 – 13 years 40 mcg
14 – 18 years 55 mcg
19 – 50 years 55 mcg
51+ years 55 mcg
Pregnancy 60 mcg
Lactation 70 mcg
If you find yourself in need of more selenium in your diet, you can try a supplement. You can find selenium in multivitamins or by itself. Whatever supplement you try, be sure to read the label.
4 Types of Selenium Supplements
When choosing a selenium supplement, pay attention to the form of selenium it contains. Selenium is available in several forms, and not all of them offer the same health benefits http://www.dreddyclinic.com/forum/viewtopic.php?f=21&t=35989. Different forms are absorbed and metabolized differently. The most important distinction between the various selenium forms is whether it’s organic or inorganic.[9]
Inorganic forms of selenium are easily absorbed through the intestine but poorly retained. Once they reach the blood, inorganic selenium is quickly filtered out by the kidneys and excreted in urine. Suffice to say, that won’t provide the full nutritional benefits of the nutrient.[9]
Conversely, organic, protein-bound selenium is better retained, utilized, and incorporated by the human body. Organic selenium supplements are often extracted from food sources. Selenium-containing amino acids, such as selenomethionine, are introduced directly into proteins, including the proteins that make up our muscles. About 90% of the selenomethionine we take in is actually absorbed in the intestinal tract, and about half of that stays in the body.[9]
The most common types of selenium found in supplements are:
1. Selenium sulfide – A topical substance that is generally not considered a supplement. Selenium sulfide is an anti-infective agent http://dreddyclinic.com/forum/viewtopic.php?f=118&t=36141 that relieves itching and flaking of the scalp. It’s often used in lotions and shampoos.[10]
2. Sodium Selenite – An inorganic form of selenium usually derived from a synthetic process.[11]
3. Selenium-enriched yeast – An organic form of selenium produced from yeast fermentation.
4. Selenomethionine and Selenocysteine – Naturally occurring organic amino acids that contain selenium. Read more
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