027: Why You Should Manage Your Selenium Status and How to Do It
Mastering Nutrition Episode 27
Selenium is critically essential to the defense against oxidative stress and to thyroid hormone metabolism. Soil concentrations cause so much variability, however, 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 27, I continue the series on managing nutritional status by teaching you how to do just that.
In this episode, you will find all of the following and more:
0:00:34 Introducing the new name, Mastering Nutrition
0:00:57 Cliff Notes
0:04:07 My story with selenium deficiency: white spots in fingernails and frequent colds
0:07:24 Soil variation plays a major role in selenium deficiency and toxicity
0:11:52 Biological roles of selenium
0:22:12 Signs of deficiency
0:32:55 Signs of toxicity
0:36:46 Optimizing between deficiency and toxicity: Hashimoto’s thyroiditis and cancer
0:42:10 Different forms of selenium in plant and animal foods
0:42:50 How selenomethionine from plants is metabolized to selenocysteine
0:48:11 How selenocysteine from animal foods enters as selenocysteine
0:48:41 How selenocysteine is converted to selenide for incorporation into selenoproteins
0:49:35 How inorganic selenite and selenate are converted to selenide using glutathione
0:54:52 Markers of nutritional status
1:06:03 Ideal ranges of markers
1:09:47 Dietary requirements and how to meet them with food
1:19:57 Why methyl-selenocysteine is not a substitute for selenocysteine and why selenomethionine is the best currently available option for a supplement
1:21:26 The proper dose of a supplement
1:27:17 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
1:30:21 Wrapping Up
Measuring and Assessing Selenium Status
I recommend using LabCorp’s plasma or serum selenium as the primary test and aiming to keep it between 90 and 140 μg/L, with the possible sweet spot being 120. μg/L and ng/mL are interchangeable, but ppm must be multiplied by 1000 to compare the values.
I recommend augmenting this with glutathione peroxidase activity from the Genova Diagnostics Oxidative Stress 2.0 (blood) panel. Measurements of enzyme activity can be subject to considerable variations between different test kits, and research studies often report them in conflicting units that cannot be standardized, so it would be potentially misleading to to derive normal or optimal ranges from the scientific literature. Therefore, I recommend using Genova’s reference range, and using it, when the value appears low, to see if it increases with selenium supplementation. Augmenting plasma selenium with this test is likely more important in premenopausal women than in men or postmenopausal women.
Recommendations: Selenium in Foods and Supplements
Selenium richest in organ meats, seafoods, and Brazil nuts. It is highly variable in all foods, but animal foods are more reliable than plant foods because the degree of variation is much lower in animal foods. Selenium is approximately half as bioavailable from seafood than from other animal foods, and is very poorly bioavailable from mushrooms and cruciferous vegetables. When calculating your selenium intake from a nutritional database, all calculations are likely to be very imprecise, but the precision will greatly increase if your selenium comes mostly from animal products. Therefore, organ meats and seafoods are the most reliable way to improve selenium status with food.
A mixed diet containing some organ meats and seafood is unlikely to require selenium supplementation unless most of the foods in the diet come from selenium-poor environments (which is very possible if you eat only local foods).
Because of the variation in foods, it is more reliable to measure your selenium status and adjust your diet if needed than to try to estimate your selenium from foods and micromanage it.
I do not recommend using methyl selenocysteine supplements because this is a detoxification product of plants and animals and unlikely to have good bioavailability.
I do not recommend using inorganic selenium such as sodium selenite or selenatebecause, although these are theoretically very bioavailable, their utilization depends on glutathione status and this could be compromised in selenium deficiency.
I do recommend using selenomethionine because this has been shown to be more effective at a lower dose than sodium selenite for the correction of deficiency. I would use 100 μg per day to correct a deficiency within four weeks, and I would use this every other day as a maintenance dose if your local foods are poor in selenium.
Based on cost, convenience, and apparent quality, I recommend this specific seller of Swanson L-selenomethionine on Amazon. It costs $9.99 for 300 capsules as is fulfilled by Amazon and eligible for Prime. It is formulated to last two years from the date of manufacture, so, taken every other day it could last you almost two years and stay fresh provided there is no large gap between manufacture and sale. Or, split among family or friends it could get used even faster and that would guarantee a fresh supply at a very low cost.
Now’s selenomethionine is also cost-effective and is a somewhat smaller bottle (250 tablets). It is slightly less expensive on iHerb ($7.86) than Amazon ($8.73) and at the iHerb price is slightly less expensive than the Swanson bottle (3.1 cents per tablet instead of 3.3 cents per capsule).
If you want a smaller bottle to ensure you will use it while it is still fresh, I would recommend Solgar selenomethionine from iHerb, which is $6.72 for 100 tablets each containing 100 μg. However, it is doubtful that this is any more cost-effective even if freshness were a theoretical concern, because it is 6.7 cents per tablet, which costs twice as much as the larger bottles.
Maps of Soil Selenium Content
Further Reading: Selenium Links and Research
The selenium chapter of Modern Nutrition in Health and Disease is a great starting place for anyone who is scientifically inclined. This is one of the few textbooks I was required to purchase in school and found so useful I kept as a cherished reference. When the most recent edition came out, I bought the Kindle version, which is incredibly easy to navigate and take notes from compared to the hardcover version of the previous addition that I also still have.
Variation in selenium content of different animal feeds from the previous source
Variation in food selenium in Belgium
This paper shows a black-and-white picture of fingernail loss in selenium toxicity.
Sex-specific and inter-individual differences in biomarkers of selenium statusidentified by a calibrated ELISA for selenoprotein P covers using plasma selenium as a proxy for selenoprotein P and why this may be less reliable in premenopausal women (or, at least, in ages 20-35) than in men or in postmenopausal (or, at least, in ages 60-80) women.
Genetic polymorphisms in methylation enzymes and selenoprotein P make a small contribution to selenium status.
Optimizing selenoprotein P with selenomethionine in Chinese subjects suffering from deficiency, why selenoprotein P is the most sensitive marker of deficiency, and the cutoff of plasma selenium needed to guarantee its optimization.
Selenium content of whole blood vs. serum is pretty similar.
Selenium content of plasma vs. serum is pretty similar.
This paper covers the conversion of selenium compounds to selenide.
This paper covers the methylation-mediated detoxification of selenium compounds.
Selenomethionine is superior to selenite in reversing deficiency in Chinese subjects.
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