Selenium is critically essential to the defense against oxidative stress and to thyroid hormone metabolism. Soil concentrations cause so much variability in the selenium content of foods that any two of us could be eating the same diet and one of us could have too little selenium and the other too much. That makes it essential to understand how to measure and manage our nutritional status. In episode 35, I continue the series on managing nutritional status by teaching you how to do just that.
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In this episode, you will find all of the following and more: 0:00:34 Introducing the new name, Mastering Nutrition; 0:01:00 Cliff Notes; 0:10:55 My story with selenium deficiency: white spots in fingernails and frequent colds; 0:14:14 Soil variation plays a major role in selenium deficiency and toxicity; 0:18:40 Biological roles of selenium (antioxidant protection, immunity, thyroid health, through glutathione peroxidases and thyroid deiodinases, control of protein function through thioredoxin reductase, other poorly understood roles); 0:29:00 Signs of deficiency (vulnerability to viral infection and other infection, hepatic cirrhosis, white fingernails that can fall out, cardiac insufficiency and enlargement of the heart with fibrosis and necrosis as occurs in Keshan disease, increased vulnerability to vitamin E deficiency, iron overload, and toxin exposure) 0:39:45 Signs of toxicity (hepatic cirrhosis, white spots and streaks in brittle fingernails, loss of hair and nails, additional signs in acute toxicity from mistakes in supplement manufacture); 0:43:45 Optimizing between deficiency and toxicity: Hashimoto's thyroiditis and cancer; 0:49:00 Different forms of selenium in plant and animal foods; 0:49:38 How selenomethionine from plants is metabolized to selenocysteine; 0:55:10 How selenocysteine from animal foods enters as selenocysteine; 0:55:30 How selenocysteine is converted to selenide for incorporation into selenoproteins; 0:56:25 How inorganic selenite and selenate are converted to selenide using glutathione; 1:01:46 Markers of nutritional status (selenoprotein P, glutathione peroxidase, selenium concentration of various body tissues with an emphasis on plasma and serum but including other blood fractions, hair, and nails) 1:12:53 Ideal ranges of markers; 1:16:42 Dietary requirements and how to meet them with food (organ meats and offal, seafood, Brazil nuts, bioavailability issues in seafood, mushrooms, and cruciferous vegetables); 1:26:45 Why methyl-selenocysteine is not a substitute for selenocysteine and why selenomethionine is the best currently available option for a supplement; 1:28:13 The proper dose of a supplement; 1:35:07 Things we will learn in the future: implications of needing methylation to both utilize enough selenium and detoxify excess; interactions with glutathione and antioxidant system; selenoprotein P becoming commercially available to health care practitioners and individuals; the rise of novel markers as we learn more about the poorly understood selenoproteins 1:37:10 Wrapping Up