# Selenium

Category: Vitamins & Minerals

Selenium is an essential trace mineral whose primary physiological role, in Ray Peat's framework, is enabling the conversion of the storage thyroid hormone thyroxine (T4) into the active metabolic hormone triiodothyronine (T3). Peat argued that selenium is essential for the…

11 passages · 1 author · 2011–2022 · Most-cited: [Ray Peat](https://bioenergeticoracle.com/md/voices/ray-peat/index.md)

Canonical page: https://bioenergeticoracle.com/concepts/selenium

## Synthesis

**Selenium** is an essential trace mineral whose primary physiological role, in Ray Peat's framework, is enabling the conversion of the storage thyroid hormone thyroxine (T4) into the active metabolic hormone triiodothyronine (T3). [Source 5, 6] Peat argued that selenium is essential for the *local production of T3 in the tissue*, making it a critical cofactor for maintaining a high metabolic rate. [Source 5] A deficiency in selenium directly impairs this conversion, leading to an accumulation of inactive T4 and symptoms of hypothyroidism, even when the thyroid gland itself is producing hormones. [Source 3, 11]

Peat consistently recommended obtaining selenium from whole food sources, specifically **seafood**, rather than relying primarily on supplements. [Source 10] He noted that anything growing in the ocean has access to selenium, iodine, and other trace minerals, whereas land-grown foods are often deficient due to soil depletion. [Source 7] He advised consuming marine foods such as shrimp, oysters, cod, sole, or halibut about once or twice a week to provide adequate selenium, along with beneficial copper and iodine. [Source 2, 5, 9] This preference for seafood was partly due to his caution regarding certain supplement forms; he considered *sodium selenite* to be pro-oxidative and potentially unsafe. [Source 10]

When supplementation was necessary, Peat viewed it as a safe and effective short-term intervention to restore thyroid function. He stated that **100 micrograms** of selenium is a safe supplemental amount. [Source 5] For correcting a deficiency that impairs T4 conversion, he suggested a loading phase of 200 mcg daily for the first week, followed by a maintenance dose of once or twice a week. [Source 1] He specifically recommended selenium in conjunction with **progesterone** to help restore thyroid and liver functions when they are suppressed by factors like excess iodine or estrogen. [Source 3] The liver is the primary site of T4 to T3 conversion, a process that requires not only selenium but also adequate **glucose**, which is why Peat linked selenium's effectiveness to a diet sufficient in carbohydrates. [Source 6]

The importance of selenium extends to mitigating the toxic effects of other dietary and environmental factors. Peat explained that the protective nutrients in cod liver oil, vitamins A and D, are so crucial that they partially offset the damage from the *polyunsaturated fats* (PUFAs) also present in the oil. [Source 2] Similarly, the selenium naturally found in seafood provides a crucial safeguard against the heavy metals like mercury that accumulate in larger, older fish. [Source 2] This protective role is part of why Peat considered occasional seafood consumption a valuable practice for maintaining overall metabolic health and resilience against stress. [Source 4, 8]

## People also ask

### How does selenium affect thyroid hormone conversion?

Peat argued that selenium is essential for the local conversion of the storage hormone T4 into the active metabolic hormone T3 in tissues, making it a critical cofactor for maintaining a high metabolic rate.

### Why did Peat prefer seafood over supplements for selenium?

Peat recommended seafood like shrimp or oysters because ocean-grown foods reliably provide selenium along with other minerals, whereas he considered certain supplement forms like sodium selenite to be pro-oxidative and potentially unsafe.

### What role does selenium play in protecting against heavy metals?

The corpus describes that the selenium naturally found in seafood provides a crucial safeguard against the toxic effects of heavy metals like mercury that accumulate in larger, older fish.

## Related concepts

- [Iodine](https://bioenergeticoracle.com/md/concepts/iodine/index.md)
- [Raw carrot salad](https://bioenergeticoracle.com/md/concepts/raw-carrot-salad/index.md)
- [Varicose Veins](https://bioenergeticoracle.com/md/concepts/varicose-veins/index.md)
- [Albumin](https://bioenergeticoracle.com/md/concepts/albumin/index.md)
- [Body temperature and pulse](https://bioenergeticoracle.com/md/concepts/body-temperature-and-pulse/index.md)
- [Bromocriptine](https://bioenergeticoracle.com/md/concepts/bromocriptine/index.md)

## Cited passages

Passage numbers match the `[Source N]` markers in the synthesis above.

### Source 1 — Ray Peat Email Advice Depository — Post 297

Ray Peat · Email · Nov 13, 2016

> **Question:** Per email: "For someone taking a supplement, how many times a week should a 200mcg pill be taken to restore t4 conversion, presuming adequate protein?"
>
> **Ray Peat:** During the first week, every day would be o.k., then I think once or twice a week is enough.
>
> **Question:** Pure encapsulations has a good selenium : just selenomethionine and cellulose, plus an ascorbyl salt.

### Source 2 — One Radio Network: Ray Peat with Patrick Timpone — October 19, 2020

Ray Peat · Passage · Oct 19, 2020

> **Patrick Timpone:** Is there a big difference, before we go, of the kinds of fish we get at the fish counter? You know, you have so many different choices. You know, salmon, cod, oysters. Any kind of ideas there from you as far as our best choices?
>
> **Ray Peat:** Yeah, you want to avoid the very big fish that are old because over years of eating little fish, they accumulate more and more toxic heavy metals. So tuna and orange roughy, for example, are usually...
>
> **Patrick Timpone:** They're pretty big, right?
>
> **Ray Peat:** Yeah, fairly old and big. And so moderate-sized fish like sole and cod, they are lower in the heavy metals. And they also are relatively low in polyunsaturated fats. So I avoid... eating very often salmon or herring or the fatty fish.
>
> **Patrick Timpone:** Do you think fish with all the challenges in the water, potential mercury, Dr. Peat, are worth eating? They'll help us to stay healthy, do you think?
>
> **Ray Peat:** Some kind of seafood about once a week will provide selenium. That's one of the very important things that you always get from seafood. So it could be shrimp. or oysters, or cod, or sole, or any kind of marine food will give you a little bit of copper and other trace minerals and iodine, along with the essential selenium, which can be deficient in land-grown food. Yeah.

### Source 3 — Ray Peat Email Advice Depository — Post 939

Ray Peat · Email · Dec 19, 2022

> **Question:** [Iodine Hypersensitivity, High TSH, and Microdosing Cynomel]
>
> **Ray Peat:** Too much iodine interferes with thyroid function, and that slows down the liver, letting T4 accumulate. The high TSH shows that your T4 isn’t high now, and selenium and progesterone will help to restore functions. Cynomel is the product with the least iodine, and it would be good to periodically test doses of about one microgram (starting by dissolving a tablet in an ounce or two of water, and testing the water starting with just a drop or two per day).

### Source 4 — Ray Peat Email Advice Depository — Post 886

Ray Peat · Email · Dec 6, 2022

> **Ray Peat:** Is there enough sugar in your diet? Do you occasionally have seafood or liver, as a source of selenium?
>
> **Question:** [Any other ideas to help with the insomnia at night?]
>
> **Ray Peat:** Something sugary (milk and honey, for example) right at bedtime might help with sleep.
>
> **Question:** I wrote to you before about taking bromocriptine for insomnia. In just a few days, .6mg of bromocriptine seems to have mostly fixed my severe insomnia. I don't like the feeling it gives me, so I'm not sure if I'll continue to take it. I'm looking for other ways to get the same effect. Do you think bromocriptine helped my sleep because of its antiserotonin properties, or because it lowers prolactin? I was thinking of trying Stablon instead, to see if it helps with my sleep as well.
>
> **Ray Peat:** That's very interesting; I don't know what Stablon's effect might be, but a couple of people tell me they have had very good results from it. I think winter-night stress involves all the hormones that regulate energy production, and getting lots of bright light on your face, head, and neck might help. A little niacinamide (100 mg), vitamins B1 and B6 (about 10 mg), and gelatin, sugar, and salt would help to maintain energy production during the dark.

### Source 5 — One Radio Network: Ray Peat with Patrick Timpone — January 18, 2021

Ray Peat · Interview · Jan 18, 2021

> **Ray Peat:** It doesn't generally taste very good.
>
> **Patrick Timpone:** Yeah, it really doesn't, does it?
>
> **Ray Peat:** Quick cooking at normal pressure, I think, is the best for taste and health.
>
> **Patrick Timpone:** Yeah. Here's one for you. How can you tell if an underactive thyroid problem is specifically... conversion from T4 to T3 within the cell versus T4 production or transportation problem. Could this be a minor iodine or selenium deficiency easily remedied by adding these in micro amounts?
>
> **Ray Peat:** Yeah, selenium, I think 100 micrograms is a safe supplement. And selenium is essential for the local production in the tissue. So it's always good to try that. But eating shellfish or seafood, halibut or cod or sole, for example, will provide enough selenium to keep your tissue supplied and active.
>
> **Patrick Timpone:** I know you're not a big supplement fan, but so you say that we all could maybe benefit from 100 mg of selenium?
>
> **Ray Peat:** Very often, yeah. It's a safe amount.
>
> **Patrick Timpone:** And then you like that progestese, right? That one. You think that's valuable regularly?

### Source 6 — Interview with Raymond Peat, Ph.D.

Ray Peat · Interview · 2011 · http://l-i-g-h-t.com/files/east-west-the-thyroid.mp4

> **Josh Rubin:** So, we need selenium to convert T4 to T3. We need glucose to make the conversion: this is important, as most people today stay away from the right types of sugars. But at the same time - from maybe exogenous sources, or the body’s inability to detox it, blood sugar issues, excess stress - the estrogen itself will block the T4 to T3 conversion as well.
>
> **Ray Peat:** And once that happens, the estrogen can reach the point at which it starts inhibiting the thyroid gland itself. The thyroid gland, to produce the proper ratio of three parts T4 to one part of T3, it does that by breaking down the thyroglobulin, a colloidal kind of glob of protein inside the follicles of the gland. This has to be digested as needed, breaking each protein molecule down and releasing these free thyroxin and T3 hormones. And estrogen inhibits the proteolytic enzyme that releases the hormones. So, first, it slows down the liver function, but then it reaches the point where it will even block the thyroid itself. And this is where women tend to have high frequency of goiter, thyroid enlargement. They call it Hashimoto’s thyroiditis, but most often it's what they used to call a colloid goiter, where, since estrogen stimulates the stress hormones in the brain, increasing TSH, estrogen causes the pituitary to drive the thyroid harder, meanwhile it's blocking the ability of the thyroid gland to secrete it, so it tends to enlarge the thyroid, and, then they get diagnosed as having thyroiditis. Progesterone happens to activate these proteins that allow the thyroid to secrete, so I advise women who have an enlarged thyroid not to take progesterone until they've taken care of the enlargement of the thyroid. Because progesterone will normalize the proteins so fast that sometimes they will go into a slightly hyperthyroid state for a few weeks.

### Source 7 — Energy Production Diabetes Saturated Fats KMUD 2011

Ray Peat · Interview · 2011 · http://www.l-i-g-h-t.com/files/herb-doctors-energy-production,-diabetes-and-saturated-fats.mp4

> **Ray Peat:** No. The good thing about anything growing in the ocean, is that it has access to selenium, iodine and other trace minerals. Where things grow inland, they depend on whatever’s in the soil. So they're often deficient in selenium and copper.
>
> **Herb Doctor:** So, farmed salmon, any kind of farmed fish or farmed shellfish, they all...(well apart from oysters they have to farm those in the ocean, I think)?
>
> **Ray Peat:** Yah.
>
> **Herb Doctor:** They'll all be deficient; then there's actually no point eating them?
>
> **Ray Peat:** Yah. Unless people know exactly what they feed them. And they probably don't.
>
> **Herb Doctor:** Then they're giving them vitamins and then you're eating recycled vitamins.
>
> **Herb Doctor:** Now Dr. Peat, what do you explain is the problems in the food chain with those things that either poison the cells directly or interfere with thyroid function? All hinge on the fact that as organisms, we need an excess of metabolic energy, to cope with the insults of the foods that we're exposed to, the drugs that we might take or environmental toxins, etc?
>
> **Ray Peat:** Yah. And diabetes, is a good model of the energy deprived state. And they're starting to see... Several years ago someone suggested that Alzheimer's disease was diabetes of the brain. And people are seeing the effects of inflammation in all of the degenerative diseases. And inflammation involves a failure of energy, and a shift to the basically, the diabetic metabolism, in which, all you can do with glucose is make lactic acid.

### Source 8 — Ray Peat Email Advice Depository — Post 888

Ray Peat · Email · Dec 6, 2022

> ## Thread 2
>
> **Question:** [Selenium, T3/T4 Ratio, and Gut Flora Affecting Liver Hormone Metabolism]
>
> **Ray Peat:** Do you get enough selenium, for example from seafood? I usually use roughly equal parts of T3 and T4, using small amounts of cynomel on most days, occasionally cynoplus. Sometimes the intestinal flora can interfere with the liver's hormone metabolism; raw carrots, milk, bamboo shoots, and aspirin are things that often help with the flora and liver function.
>
> **Question:** [T4 Competes Against T3; Liver's Antithyroid Effects]
>
> **Ray Peat:** Experiments with brain slices showed that T4 competes against T3, causing an antimetabolic effect. Liver has all the nutrients, but it isn't ideal, because it also has antithyroid effects.

### Source 9 — Iodine, Spider Veins, Oxalates, Fat Loss

Ray Peat · Interview · Aug 4, 2020 · https://www.youtube.com/watch?v=6uTJLfQUJOs

> **Jodelle Fitzwater:** Okay, and then how would she go about starting to handle sulfur well? Because it sounds like she doesn't handle sulfur-rich foods and she wants to be able to.
>
> **Ray Peat:** The trace elements and vitamins are making sure that you're... fish or other seafoods from the ocean. One meal of that a week will provide selenium and other minerals. And having eggs every day will provide not only an abundance of the sulfur amino acids, but also a good balance of the vitamins
>
> **Jodelle Fitzwater:** okay and then we have Naomi and she was curious about she heard that you use hydrogenated coconut oil instead of cold-pressed and she wanted to know why The filtration is one thing.
>
> **Ray Peat:** The so-called virgin coconut oil, sometimes it has a delicious flavor, which is great for making ice cream. I've made using no cream at all, but an egg to emulsify. the unfiltered coconut oil you get a delicious fresh coconut tasting ice cream so it's good for flavoring or making cookies or something but it's a staple those unfiltered flavorful things contain enzymes that can break down the fats and lead to rancidity but there are also a lot of allergenic materials and quite a few people have a bad reaction to. unfiltered or poorly filtered coconut oil and in the process of solidifying it by hydrogenation they always start with a very well filtered oil and then ordinary coconut oil contains around 3% of the polyunsaturated fatty acids and The small percentage of PUFA is what makes coconut oil so much safer than other vegetable oils. But still, that 3% over a lifetime, those tend to and proceed to their toxic effects. So for total avoidance, as far as possible. If I could find a safely hydrogenated butter, I think I would do that, but the process would destroy the good flavor of butter, which is its main value.

### Source 10 — Ray Peat Email Advice Depository — Post 501

Ray Peat · Email · Jun 18, 2018

> **Ray Peat:** There’s an article about cascara on my website, [raypeat.com](http://raypeat.com/) . Hives usually result from food sensitivities on a background of hypothyroidism, and hypothyroidism often leads to stress syndromes that affect the personality. There are several related articles on my website. Vitamin E, and including some liver and aged cheese in the diet, and correcting hypothyroidism, help to clear up blood clots.
>
> **Question:** speaking of the thyroid, do you recommend sodium selenite as safe? Since it is pro-oxidative, but it is included in alot of selenium supplements. What sort of selenium supplement would you recommend? And at what dose? Also, is low dose iodine supplementation as potassium iodide recommended? (150mcg taken on some days)
>
> **Ray Peat:** I think having seafood once or twice a week is best for selenium and iodine.

### Source 11 — Ray Peat Email Advice Depository — Post 880

Ray Peat · Email · Dec 5, 2022

> **Question:** I've been trying to figure out why I now respond to cytomel differently than in the past. 2mcg with a meal makes my feet extremely cold. Along with the cold feet, I now get anxious and depressed instead of happy and calm. Even having a cup of sugar in milk doesn't make my feet warmer. I've been eating more protein, almost a gallon of milk, and eating liver for more vitamin A. Is there another nutrient that I could check, to see if I have some deficiency?
>
> **Ray Peat:** Selenium (reliably present in sea food) is essential for good thyroid function. Have you tried other products, such as Armour or Cynoplus or Proloid-S?

_Generated 2026-07-20 from the Bioenergetic Oracle corpus._