Selenium (Se)

Question 1

In what forms do Se occur in food? what is the bioavailability of Se?

Answer 1

Most Se in foods is combined with derivatives of a.a methionine and cysteine. Selenomethionine is derived from animal sources and selenocysteine is derived from animal food sources.
2. 50 - 100% but can be influenced by luminal factors.

Question 2

What are the metabolic effects of Se deficiency?

Answer 2

1. Oxidative injury, increased susceptibility to mercury, altered thyroid hormone metabolism, increased plasma glutathione, and an altered activity of the biotransformation enzymes.

Question 3

What are the biochemical functions of Se?

Answer 3

Se is a required cofactor in glutathione, iodine, and thyroid metabolism.
2. Se dependent enzymes are glutathione peroxidase and selenoprotein P (both with antioxidant properties), and iodothyronine deiodinase.

Question 4

What are good sources of Se? what are the RDA? What is the recommended parenteral supplemental dose for adults?

Answer 4

1. Fish, meat(organ), eggs,milk, and shellfish
2. 55/55mcg/day for all groups.
3. 20-60mcg/day.

Question 5

What is the name for Se toxicity? How do we prevent it?

Answer 5

1. Selenosis

2. Consumption of <200mcg/day or no more than 5mcg/kg/day is recommended.

Question 6

How do we assess Se status? What’s the difference between plasma Se and erythrocyte Se concentration?

Answer 6

1. Using general guidelines, plasma/serum Se concentrations >100mcg/L represent adequate Se status.
2. Plasma/serum Se reflects recent intake of Se, while the erythrocyte concentration indicates long-term Se status.