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The FAQ is our community collection of frequently asked questions, common practices, shared wisdom, and other things that might be useful, or that are useful to have here.

Blood Tests: Which ones should I get? What are optimal levels?

Warning: Do not trust these data blindly. Listen to Ray Peat's interviews. Click on links. Search the forum.

Thyroid status

TSH < 0.4

total T3 = higher end of normal rane

total T4 = lower end of normal range


total cholesterol = at least 160, preferably 200 before starting thyroid supplementation


Prolactin = male 4-7 optimal for fertility, female 2-12

Prolactin is a reliable biomarker for inflammation in blood tests ( with regard to tissue concentrations where it matters ) and correlates strongly with serotonin and estrogen levels.

If you have high prolactin, you are not healthy.

more info


Sodium = middle of the scale

Potassium = middle of the scale


D = 50 ng/ml ... "is a good goal. The point at which it lowers parathyroid hormone would be the right amount."

albumin > 40 (well above)

glucose = 70 - 110


Carrot Salad: Why, What, When?

Carrots are a very safe type of fiber that is resistant to full digestion and does not feed endotoxin producing bacteria ( bamboo shoots are similar ).

Carrot fiber, when it reaches the region of the intestine containing large amounts of these harmful bacteria, will act as a 'net' of sorts and sweep out some bacteria for excretion.

Ray Peat recommends peeling the carrot longitudinally, rinsing, then combining with olive/coconut oil, salt, and vinegar to improve both the antiseptic effects and taste. The carrot salad is a safe, cheap, and easy way to begin reducing systemic inflammation and pave a path to recovery.

The juice of a carrot is not of value as it lacks the cleansing fiber and makes the beta-carotene in carrots more available for digestion. Beta-carotene has an anti-thyroid effect.


Why does Peat specifically mention coffee as a source of magnesium? I have have not seen any compelling evidence that coffee has significant amounts of Mg.


Why does Ray Peat recommend milk?

Milk in context: allergies, ecology, and some myths
Calcium and Disease: Hypertension, organ calcification, & shock, vs. respiratory energy
Radio Interviews:
Milk - KMUD, 2011-08-19
Milk, Calcium and Hormones - East West Healing, 2011
Forum discussions

Doubts: Doesn't milk contain estrogen, tryptophan...?

I can't tolerate milk. How to overcome it?

How to take: Sugar-to-Milk ratio

Fats, PUFAs, Saturates, oh my

"EFA": Why are they depleted in degenerative diseases?

The most unsaturated fats are the first one to be degraded by stress. [1]

Fish oil: Why is it bad for me?


PUFA stands for polyunsaturated fatty acids. (”Unsaturated fatty acids: Nutritionally essential, or toxic?” doesn't define it explicitly, but gives context.)

What makes them antithyroid?

PUFAs block thyroid in many different ways, oxidation is one part of it. Oleic is the least harmful of all the unsaturated fats. Omega 6 is a precursor to inflammatory products and inflammation initiates a whole cascade of bad things. Even without oxidation PUFA is able to block thyroid. Here is a quote from RP. Cooking makes olive oil more toxic, mainly by destroying anti oxidants and oxidizing 10 % PUFA. But this PUFA gets oxidized inside our body even when it was cold pressed and unheated. PUFA and estrogen increases each others activity. Estrogen blocks hormone secretion from thyroid.

Why do they accumulate in fat cells?

Polyunsaturated fatty acids are preferentially stored, and fat cells preferentially oxidize saturated fats, so PUFA and their random oxidation products accumulate, and are preferentially released by stress, and synergize with estrogen in various ways.[1]

Vegetable oils: What are the dangers? (ELI5)

Most plants' goal is to have as many of their seeds spread as far as possible. Thus, plants often encapsulate seeds in appetizing wrapper to entice organisms to ingest the seeds. At the same time the seeds contain substances that would inhibit the ability of this organism to digest (destroy) those seeds. One of the most commonly used substances by the plants are the oils found in the seeds. Seed oils happen to be a powerful suppressor of both digestive and metabolic activity (the two are closely related). Most vegetable oils sold on the market are extracted from seeds (sunflower, cottonseed, canola, rapeseed, soybean, peanut, etc), and as such are likely to suppress both metabolism and digestion. In addition, many of the seeds contain toxic substances based on the well-known poison cyanide to further discourage organisms from attacking/eating the seeds. (Pro)anthocyanidins and some of the most common cyanide-derived poisons found in virtually all seeds.[2]

As a general rule, the seeds of a plant contain the most powerful toxins and should be avoided as food unless there is nothing else available. In contrast, olive oil and coconut oil are extracted from the actual fruit and not from seeds. I guess another distinction is that both olive and coconut oil are actually fruit oils and not vegetable oils. The fruit is typically meant to be eaten as a means of spreading the seeds and usually contains beneficial substances like sugars and pro-metabolic oils.

The vegetable plant, as opposed to the seeds, is usually less toxic when eaten but it is still very difficult to digest (most plants are mostly cellulose and water) and it is usually not very calorie-dense. Given our large brains and daily caloric demands, it just does not seem likely that vegetables (and derivative oils) are the food we are supposed to eat the most.

Other Topics

Age pigment: What is it?

Age pigment (lipofuscin) is the brown material that forms spots on aging skin, and that accumulates in the lens of the eye forming cataracts, and in blood vessels causing hardening of the arteries, and in the heart and brain and other organs, causing their functions to deteriorate with age. It is made up of oxidized unsaturated oils with iron.[3]

Cloudy urine: What does it indicate?

If you are drinking lots of milk for example or (eating) a high meat diet, the phosphate has to get excreted. The phosphate shows up in the urine and precipitates in the presence of either magnesium or calcium.

It only precipitates if the pH is above a certain point, and so if you have a very high protein diet, most of the time your urine will be acidic, and it will be clear despite having a tremendous amount of phosphate in it. However when something raises the pH of your urine, which can be eating a lot of fruit or vegetables, or hyperventilating (if you blow out too much carbon dioxide), the pH of your urine goes up to keep your blood at the right pH (slightly alkaline), and when your urine pH is neutral or higher on the alkaline side, then any phosphate and calcium is going to precipitate and make your urine cloudy.[4]


What role does it play in overall metabolic and cellular health ?

It has many effects, for example by mass action it modifies carboxylations and decarboxylations, and it affects the formation of urea, and stabilizes the Krebs cycle by anaplerosis, lowers free radicals, stimulates new bone formation, lowers peripheral vascular resistance, and is generally antiinflammatory. The most important long-term effect might be protection against harmful glycation, by forming carbamino groups in regulatory sites. As a Lewis acid, its association with proteins has inductive effects. As it's formed and converted to carbonic acid, leaving the mitochondria it removes water, and participates in ion regulation. It limits the formation of lactic acid, and has a stabilizing effect on nerves. As an acidic adsorbent, it tends to stabilize cell function and metabolism.[1]

What helps to boost CO2 retention?

Ray Peat - Absorbing it through the skin [CO2 therapy] is safe, also bag-breathing can gradually allow the nerves to adapt to a higher concentration. In a high concentration, it burns the membranes by its acidity. Lowering serotonin is one way to shift the cells' balance in the right direction, but keeping the right balance of thyroid (producing CO2) and estrogen (which increases lactate formation and stimulates hyperventilation) is the basic way to optimize CO2. Activity increases CO2 production when the health is good. [1]

Cholesterol: Why is it increased in hypothyroidism?

Cholesterol is precursor of steroid hormones and bile acids. When metabolism is slow less cholesterol is converted.


Glycolysis is a pathway that partially catabolizes carbohydrates, primary glucose. Under aerobic conditions pyruvate enters the Krebs cycle. Under anaerobic conditions pyruvate is converted to lactate. Most cells can not produce enough ATP by glycolysis alone to meet their energy requirements.

"Stuck in glycolysis" means that you never reach the following pathways, Krebs cycle and oxidative phosphorylation and just keep producing lactic acid.

Oxidative phosphorylation

Oxidative phosphorylation is quantitatively the most important mechanism by which energy derived from fuel molecules can be transferred to ATP. It consumes the products of the Krebs cycle to generate ATP.

Panic attacks: What could be the cause?

When things are working properly, tissues are activated according to their use in adapting to the environment, and produce CO2 in proportion to their response; CO2 adjusts the blood supply while promoting mitochondrial energy production and regulating energy use. It stimulates normal breathing, while stabilizing (restraining activity of) nerves and other tissues.

In the absence of oxygen (or presence of injury that prevents its use), lactate is produced instead of CO2, and displaces CO2 from the system, activating emergency alarm systems, potentially creating vicious circles of hormone changes and inflammation. Intestinal irritation (e.g., undigested food and bacterial toxin) releases large amounts of serotonin. Serotonin (named for its ability to constrict blood vessels) impairs oxygen use and increases lactate production. Hypothyroidism reduces tissues' ability to use oxygen and produce CO2, and slows digestion, increasing a tendency to produce serotonin, which activates stress hormones, etc.

Bag breathing can increase the carbon dioxide in the tissues, helping to reduce lactate production, but stabilizing the metabolic system is the real solution. With high glycogen stores, minor stresses don't tip the system into glycolytic metabolism easily.[1]


  1. 1.0 1.1 1.2 1.3 1.4 20 Questions with Ray Peat
  2. Wikipedia: Proanthocyanidin
  3. Iron's Dangers
  4. Ray Peat, Radio Interview: Health and Diet - One Radio Network, 2014