Selenium Flashcards
What is Selenium?
Selenium replaces the sulfur in the amino acids hence in the diet selenium is in the organic form although it can be found in inorganic forms in dietary supplements
What is selenium’s function?
Selenium has many different functions as it has many roles in different enzymes and proteins in the body
It is an essential, antioxidant nutrient and is found in glutathione peroxide which prevents oxidative damage to phospholipids and cell membranes
Selenium is found in the enzyme deiodinase which is the enzyme that converts T4 -> T3 (thyroid hormone)
What is NZ’s intake of selenium like?
In the ANS women in NZ were not consuming enough selenium to meet the RDI, men were
This may be due to different foods being consumed by men and women
What foods have selenium?
Food that are high selenium include grains, bread, fish and seafood, poultry and eggs
It is also found in fruit and vegetables however these are poor sources
Some plants such as brazil nuts, mushrooms and garlic accumulate selenium
Selenium in brazil nuts is quite bioavaliable - can be absorbed and used
How is selenium absorbed?
About 80% is absorbed, no regulation
Organic selenium is transported actively and inorganic is transported passively
Plasma levels maintained by urinary excretion via kidney - 50-60% of dietary selenium excreted in urine
Levels in tissue/blood reflect intake
What is selenium deficiency?
Selenium deficiency in sheep caused sheep to be still born or die in the first few days, had an unsteady gate and arched back. Now sheep given supplement to prevent this
In humans Keshans disease occurred in China which resulted in cardiomyopathy in children and pregnant women, not seen in NZ as we have a more diverse diet than Chinese
How can we improve selenium intake?
There are no public health strategies implemented as NZ has adapted to low levels of selenium. Increase in selenium intakes from imported Australian wheat used to make flour
What is selenium toxicity?
It is rare to develop selenium toxicity from diet
If you take lots of selenised yeast supplements could develop toxicity
What is fluoride?
Low levels in food and untreated water
100% of fluoride is absorbed from diet and excreted in urine via kidney
Fluoride found in toothpaste, fish, tea and water
What is fluoridated water?
Non-fluoridated NZ water/water from lakes and streams has about 0.1ppm however ministry of health recommends 0.7-1.0ppm in water we consume as there is evidence that fluoride decreases dental caries at this level
