An HPLC method has been validated for the analysis of L-(+)-Selenomethionine on a Thermoquest PDA System using a Phenomenex Aqua Column and standardized chromatographic conditions. The method provides accurate values of L-(+)- Selenomethionine content and measures the levels of free methionine in commercial samples of L-(+)Selenomethionine.

Selenium Supplements:
Relative bioavailability and health benefits

Selenium is a vital trace element nutrient with multiple roles in the growth and functioning of living cells in higher animals and humans. This element is unevenly distributed in the earth’s crust.

The primary nutritional source is the soil from which it is absorbed by plants and enters the food chain. Geographical variations in the selenium status of populations therefore exist, necessitating selenium supplementation. The recommended levels for selenium supplementation in humans are 50-200 mcg/day.

Selenium supplements include:

• Inorganic salts such as sodium selenite and sodium selenate
  
  
• Selenium/amino acid chelates/aspartate
  
  
• L(+)-Selenomethionine
  
  
• Selenium yeast (where selenium is present as L-(+)Selenomethionine).

Inorganic selenium salts and chelated forms of selenium (chelates, aspartates) are broken down into elemental selenium. It is important to note that elemental selenium is not bioavailable and may have toxic effects at levels only four to five times the amount normallyingested in the human diet.

L(+)-Selenomethionine contains selenium in a molecularly integrated form and is therefore directly incorporated into the proteins in the body in place of the amino acid, methionine. Amino acid chelates and inorganic selenite / selenate are degraded by compounds such as ascorbic acid to elemental selenium which is not bioavailable. Metabolism of L(+) Selenomethionine. L(+)-Selenomethionine has the sulfur atom in L(+)-Methionine replaced by selenium. It is converted to selenocysteine in the body. Selenocysteine is then incorporated into selenoproteins. The sequence is schematically represented in the figure below:

It is reported that the replacement of methionine by selenomethionine in the protein structure does not induce any functional changes in the protein molecule. In fact, selenium in the protein structure protects DNA from oxidation more efficiently than the original sulfur in methionine. The carbon-selenium bond is more easily broken during photochemical reactions as compared to the carbon-sulfur bond. Thus L-(+)Selenom-ethionine preferentially "accepts" the energy from light. Therefore topical or orally administered L-(+)Selenomethionine offers greater protection to the skin against damage by ultraviolet light1.

One study reports that selenium levels in the red blood cells of subjects treated with selenomethionine (in the form of selenium yeast) increased by100% after 16 weeks supplementation2. Neither selenite nor selenate supplementation produced significant increases under the same conditions. Thus selenomethionine and yeast containing selenomethionine are the appropriate forms of selenium for use in nutritional supplements and foods including infant formulas3.

However, if selenomethionine is supplied in the form of selenium yeast, it is important to ascertain that the selenium in the yeast is present in the form of L-(+)-Selenomethionine. Good commercial samples of selenium yeast typically contain 1000-2000 ppm of selenium, most of which is in the form of L-(+)-Selenomethionine. However, some samples may contain substantial amounts of inorganic selenium compoundsinstead of L-(+)-Selenomethionine.

References:

1. Burke, K.E. et al.(1992) Nutr.Cancer.17: 123-127.

2. Alfthan, G. et al. (1991) Am. J. Clin. Nutr. 55:120-125.

3. Schrauzer, G.N. (1998) Journal of Medicinal Food, 1(3):201-205.

The selenium in commercial selenium yeast samples is present as L(+) Selenomethionine. The minimum elemental selenium content is about 1080 mcg/g. L(+)Selenomethionine (5000 DCP) contains 5000 mcg/g elemental selenium. About 4.6 g of selenium yeast would be required to obtain the selenium levels contained in one gram of L-(+)-Selenomethionine (5000 DCP).

In his own words....

"Although my ten day trip to India, was about business, it was impossible not to soak up the colorful and rich culture of the region. India is an ancient country, but only a close-up and personal encounter with the people and their way of life can give you a sense of how ancient this culture really is.

Consider the special reverence that Indians have for domesticated and wild animals. Cows, bulls, goats, horses and dogs mingle freely with the crowd and road traffic, and nobody is annoyed by this. On the contrary, the incredible congestion on the road seems to be better coordinated with the random presence of animals, popularly referred to as "speed breakers". Not far from the road (and in the backyards) you may see numerous "cobra houses". These termite-built clay structures are inhabited by cobras, but remarkably most people living around find ways to be at peace with snakes and not to destroy their habitats. Almost every, if not every, animal has a special significance in the Indian tradition. The elephant is regarded as a symbol of good luck and if you come close enough to a friendly elephant you may be fortunate to be "blessed" by the animal- (who puts the tip of the trunk on the top of your head).

Mahatma Gandhi’s philosophy of non-violence is still alive and well in India. I could literally "taste" it when I stayed a vegetarian for ten days. Being vegetarian does not essentially mean adopting a diet of salads and remaining hungry. However, it definitely takes experience to be vegetarian without hurting yourself.

On a food note I did not have any stomach problems while trying new foods, and the credit goes (in my opinion) to the morning glass of "Lassi" (Indian sour milk, a source of healthy probiotics), and specially prepared black tea with spices called "Masala tea".

Last but not the least, let me inform the readers that the Bangalore based Sami Chemicals and Extracts, a manufacturer for Sabinsa Corporation in India, is growing in leaps and bounds. The newly completed R&D complex looks like a science fiction lab, with its see-through partitions and state of the art facilities. This operation is devoted to the standardization of herbal extracts, nutritional supplements and specialty fine chemicals, with a focus on developing cost-effective manufacturing processes. Overall this trip to India provided me with a deeper understanding of not only the manufacture of Ayurveda products, but also drove home the meaning of tradition in the birth place of Ayurveda."